接上篇 hibernate入门使用系列 3-- 关系映射篇（中）



开我写的前3篇中，分别讲了one-to-one, one--to-many, many-to-one 。

这篇，主要讲的是 n：n 的关系。即：many-to-many。

我们以老师和学生为例，一个老师可以交很多学生，同样一个学生可以拥有多个老师，所以，他们之间的关系就是n：n的。

实体模型：



从实体模型来看。有2个对象，但是为了在数据库中表示出2者的n:n的关系，我们还得引入一张表。所以，sql脚本如下：

 use HibernateQuickUse;
drop table if exists teacher_student_relation;
drop table if exists Teacher;
drop table if exists Student;

create table Teacher (
	tid varchar(32) primary key,
	name varchar(32) not null
);

create table Student (
	sid varchar(32) primary key,
	name varchar(128) not null
);

create table teacher_student_relation (
	id integer auto_increment primary key,
	teacher_id varchar(32) not null,
	student_id varchar(32) not null,
	foreign key(teacher_id) references Teacher(tid),
	foreign key(student_id) references Student(sid)
);

通过模型，创建java类如下：

Student.java

package org.py.hib.relation.many2many;

import java.util.HashSet;
import java.util.Set;

/**
 * Student entity.
 */

@SuppressWarnings("serial")
public class Student implements java.io.Serializable
{
	private String id;

	private String name;

	private Set<Teacher> teachers = new HashSet<Teacher>(0);

	public Student()
	{
	}

	public String getId()
	{
		return this.id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public String getName()
	{
		return this.name;
	}

	public void setName(String name)
	{
		this.name = name;
	}

	public Set<Teacher> getTeachers()
	{
		return teachers;
	}

	public void setTeachers(Set<Teacher> teachers)
	{
		this.teachers = teachers;
	}
}

Teacher.java:

package org.py.hib.relation.many2many;

import java.util.HashSet;
import java.util.Set;

/**
 * Teacher entity.
 */

@SuppressWarnings("serial")
public class Teacher implements java.io.Serializable
{
	private String id;

	private String name;

	private Set<Student> students = new HashSet<Student>(0);

	public Teacher()
	{
	}

	public String getId()
	{
		return this.id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public String getName()
	{
		return this.name;
	}

	public void setName(String name)
	{
		this.name = name;
	}

	public Set<Student> getStudents()
	{
		return students;
	}

	public void setStudents(Set<Student> students)
	{
		this.students = students;
	}

}

xml映射文件如下

Student.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
	<class name="org.py.hib.relation.many2many.Student"
		table="student">
		<id name="id" type="java.lang.String" column="sid" length="32">
			<generator class="uuid" />
		</id>

		<property name="name" type="java.lang.String" column="name"
			length="128" not-null="true" />

		<set name="teachers" table="teacher_student_relation" cascade="save-update" inverse="false">
			<key column="student_id" not-null="true" />

			<many-to-many column="teacher_id"
				class="org.py.hib.relation.many2many.Teacher" 
				/>
		</set>
	</class>
</hibernate-mapping>

 注意：

 set中的 table 指向的是数据库中的关联表。

cascade 用的是save-update , 且inverse用的是false，这样的话，当进行修改和保存和删除时，关联表中的记录也会删掉.

如果cascade 用的是 all 那么连同student表中的记录也会被删除掉。

key中的column指的是： 关联表中与Student发生关系的字段。

而many-to-many中的column指的是：关联表中，与class(这里是：org.py.hib.relation.many2many.Teacher)发生关系的字段。

关于inverse，请参考上篇：hibernate入门使用系列 3-- 关系映射篇（中）

Teacher.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
	<class name="org.py.hib.relation.many2many.Teacher"
		table="teacher">
		<id name="id" type="java.lang.String" column="tid"
			length="32">
			<generator class="uuid" />
		</id>

		<property name="name" type="java.lang.String" column="name"
			length="32" not-null="true" />

		<set name="students" table="teacher_student_relation" cascade="save-update"
			inverse="false">
			<key column="teacher_id" not-null="true" />
			<many-to-many class="org.py.hib.relation.many2many.Student"
				column="student_id" />
		</set>
	</class>
</hibernate-mapping>

  注意：

这里的inverse也采用了false，这样子的话，Teacher和Student都维护关系表中的关系。

测试类，Many2ManyTest.java

package org.py.hib.relation.many2many;

import java.util.Iterator;
import java.util.List;
import java.util.Set;

import junit.framework.Assert;
import junit.framework.TestCase;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.After;
import org.junit.Before;

public class Many2ManyTest extends TestCase
{
	private SessionFactory factory;

	@Before
	public void setUp() throws Exception
	{
		Configuration conf = new Configuration().configure();
		factory = conf.buildSessionFactory();
	}

	/**
	 * 测试添加
	 * @throws Exception
	 */
	public void testSave() throws Exception
	{
		System.out.println("\n=== test save ===");

		Teacher teacher1 = new Teacher();
		teacher1.setName("teacher_1");

		Teacher teacher2 = new Teacher();
		teacher2.setName("teacher_2");

		Student stu1 = new Student();
		stu1.setName("student_1");

		Student stu2 = new Student();
		stu2.setName("student_2");

		stu1.getTeachers().add(teacher1);
		stu1.getTeachers().add(teacher2);

		stu2.getTeachers().add(teacher2);
		teacher1.getStudents().add(stu2);

		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();

			session.save(stu1);
			session.save(stu2);
			tran.commit();

			Assert.assertNotNull(teacher1.getId());
			Assert.assertNotNull(teacher2.getId());

			Assert.assertNotNull(stu1.getId());
			Assert.assertNotNull(stu2.getId());

		} catch (Exception ex)
		{
			tran.rollback();
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试从Teacher查询
	 * @throws Exception
	 */
	@SuppressWarnings("unchecked")
	public void testFindFromTeacher() throws Exception
	{
		System.out.println("\n=== test find from Teacher ===");
		Session session = null;
		try
		{
			session = factory.openSession();
			Iterator<Teacher> iter = session.createQuery("from Teacher").iterate();
			while (iter.hasNext())
			{
				Teacher teacher = iter.next();
				Assert.assertNotNull(teacher.getId());
				String teacherName = teacher.getName();
				if ("teacher_1".equals(teacherName))
				{
					Set<Student> stus = teacher.getStudents();
					Assert.assertEquals(stus.size(), 2);
					for (Student stu : stus)
					{
						String stuName = stu.getName();
						Assert.assertNotNull(stu.getId());
						Assert.assertTrue(stuName.equals("student_1") || stuName.equals("student_2"));
					}
				} else if ("teacher_2".equals(teacherName))
				{
					Set<Student> stus = teacher.getStudents();
					Assert.assertEquals(stus.size(), 2);

					for (Student stu : stus)
					{
						String stuName = stu.getName();
						Assert.assertNotNull(stu.getId());
						Assert.assertTrue(stuName.equals("student_1") || stuName.equals("student_2"));
					}
				} else
				{
					throw new Exception("teacher name error exception.");
				}
			}
		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试从Student查询
	 * @throws Exception
	 */
	@SuppressWarnings("unchecked")
	public void testFindFromStudent() throws Exception
	{
		System.out.println("\n=== test find from Student ===");
		Session session = null;
		try
		{
			session = factory.openSession();
			Iterator<Student> iter = session.createQuery("from Student").iterate();
			while (iter.hasNext())
			{
				Student stu = iter.next();
				Assert.assertNotNull(stu.getId());
				String stuName = stu.getName();
				if ("student_1".equals(stuName))
				{
					Set<Teacher> teachers = stu.getTeachers();
					Assert.assertEquals(teachers.size(), 2);
					for (Teacher teacher : teachers)
					{
						String tName = teacher.getName();
						Assert.assertNotNull(teacher.getId());
						Assert.assertTrue(tName.equals("teacher_1") || tName.equals("teacher_2"));
					}
				} else if ("student_2".equals(stuName))
				{
					Set<Teacher> teachers = stu.getTeachers();
					Assert.assertEquals(teachers.size(), 2);
					for (Teacher teacher : teachers)
					{
						String tName = teacher.getName();
						Assert.assertNotNull(teacher.getId());
						Assert.assertTrue(tName.equals("teacher_1") || tName.equals("teacher_2"));
					}
				} else
				{
					throw new Exception("student name error exception.");
				}
			}
		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试修改
	 * @throws Exception
	 */
	public void testModify() throws Exception
	{
		System.out.println("\n=== test modify ===");
		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();

			Teacher t1 = (Teacher) session.createQuery("from Teacher t where t.name='teacher_1'").list().get(0);
			t1.setName("new_teacher_1"); // 修改用户名 = m_name2.（原来用户名= m_name）

			Set<Student> stus = t1.getStudents();
			for (Student stu : stus)
			{
				if (stu.getName().equals("student_1"))
				{
					stus.remove(stu);
					break;
				}
			}

			tran.commit();

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}

		/*
		 * 修改后再查询
		 */
		System.out.println("\n=== test find from Teacher after modify===");
		try
		{
			session = factory.openSession();
			Iterator<Teacher> iter = session.createQuery("from Teacher").iterate();
			while (iter.hasNext())
			{
				Teacher teacher = iter.next();
				Assert.assertNotNull(teacher.getId());
				String teacherName = teacher.getName();
				if ("new_teacher_1".equals(teacherName))
				{
					Set<Student> stus = teacher.getStudents();
					Assert.assertEquals(stus.size(), 1);
					for (Student stu : stus)
					{
						String stuName = stu.getName();
						Assert.assertNotNull(stu.getId());
						Assert.assertTrue(stuName.equals("student_2"));
					}
				} else if ("teacher_2".equals(teacherName))
				{
					Set<Student> stus = teacher.getStudents();
					Assert.assertEquals(stus.size(), 2);

					for (Student stu : stus)
					{
						String stuName = stu.getName();
						Assert.assertNotNull(stu.getId());
						Assert.assertTrue(stuName.equals("student_1") || stuName.equals("student_2"));
					}
				} else
				{
					throw new Exception("teacher name error exception.");
				}
			}
		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试删除
	 * @throws Exception
	 */
	public void testDelete() throws Exception
	{
		System.out.println("\n=== test delete ===");
		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();

			Iterator<Teacher> iter = session.createQuery("from Teacher").iterate();
			while (iter.hasNext())
				session.delete(iter.next());

			tran.commit();

			Integer count = (Integer) session.createQuery("select count(*) from Teacher").list().get(0);
			Assert.assertEquals(0, count.intValue());

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}

		/*
		 * 删除后再查询
		 */
		System.out.println("\n=== test find after delete ===");
		try
		{
			session = factory.openSession();

			Integer num = (Integer) session.createQuery("from Teacher").list().size();
			Assert.assertEquals(0, num.intValue());

			num = (Integer) session.createQuery("from Student").list().size();
			Assert.assertEquals(0, num.intValue());

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 
	 */
	@After
	public void tearDown() throws Exception
	{
		factory.close();
	}

}

从这个例子中可以看出，many-to-many中，需要引入第3张表来表示关系。

附件中有源代码。

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接上篇 hibernate入门使用系列 2-- 关系映射篇（上）

上篇讲了1：1，那么这次继续讲1：n和n：1。

这次用到的例子是Father和child之间的关系。一个father可以有n个child，但是1个child只有一个father。这里只说生父。至于其他的继父、养父、干爹等等，不再范围之内。

好吧。还是同前面的一样。现建立实体模型如下：

根据模型创建数据库。sql脚本如下：

use HibernateQuickUse;
drop table if exists Child;
drop table if exists Father;

create table Father (
	id varchar(32) primary key,
	name varchar(32) not null
);

create table Child (
	id varchar(32) primary key,
	name varchar(128) not null,
	father_id varchar(32) not null,
	foreign key(father_id) references Father(id)
);

根据模型创建java对象。

Father.java：

package org.py.hib.relation.one2many;

import java.util.HashSet;
import java.util.Set;

/**
 * Father entity.
 */

@SuppressWarnings("serial")
public class Father implements java.io.Serializable
{
	private String id;

	private String name;

	private Set<Child> children = new HashSet<Child>(0);

	public Father()
	{
	}

	public String getId()
	{
		return this.id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public String getName()
	{
		return this.name;
	}

	public void setName(String name)
	{
		this.name = name;
	}

	public Set<Child> getChildren()
	{
		return children;
	}

	public void setChildren(Set<Child> children)
	{
		this.children = children;
	}
}

 Child.java：

package org.py.hib.relation.one2many;

/**
 * Child entity.
 * @author MyEclipse Persistence Tools
 */

@SuppressWarnings("serial")
public class Child implements java.io.Serializable
{
	private String id;

	private String name;

	private Father father;

	public Child()
	{
	}

	public String getId()
	{
		return this.id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public Father getFather()
	{
		return this.father;
	}

	public void setFather(Father father)
	{
		this.father = father;
	}

	public String getName()
	{
		return this.name;
	}

	public void setName(String name)
	{
		this.name = name;
	}

}

映射文件如下：

Father.hbm.xml：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="org.py.hib.relation.one2many.Father" table="father">
        <id name="id" type="java.lang.String" column="id" length="32">
            <generator class="uuid" />
        </id>

        <property name="name" type="java.lang.String" column="name" length="32" not-null="true"/>
        
	<set name="children" table="child" cascade="all" inverse="true">
            <key column="father_id" />
            <one-to-many class="org.py.hib.relation.one2many.Child" />
        </set>
    </class>
</hibernate-mapping>

这里要说说 "set" 这个标签里面的内容。

"name"是Father里面的属性的名字。

"table"表示它对应的是数据库中的哪个表。

cascade="all" 表示所有的操作都级联操作。

"inverse"表示关系的维护由谁来执行。true表示不由自己执行，而有对应的另外一方执行。false则相反，表示由自己维护关系。这里设置成 true 是由原因的。如果说把它设置成为false，那么就由他来维护关系了。

这里得说一下inverse属性的问题。在one-to-many中，如果关系由one来维护，那么会很麻烦，性能也会很低。每次对many一方的一条记录进行增、删、改 时都会多一次update操作。原因很简单，因为关系的维护设置在了one这一方，所以对many的每一次操作，one这一方都要维护一次双方的关系。

这个就好像皇帝和老百姓的关系。试问，是来一个老百姓，皇帝就宣布他是我的子民，还是由老百姓直接选择做那个皇帝的子民更加有效率呢？呵呵。不知道这个例子大家有没有明白。关于inverse的更具体的说明，在javaeye上搜一下，就会发现有很多。这里推荐一篇，我认为讲得很明白的：主题：inverse。

"key" 中的 "column" 表示在table(这里的table是child)中, 跟Father关联的字段名称。这里是"father_id"。可以看看开始的sql脚本。

one-to-many 表示father和children的关系。class则表示是同哪个类是这种关系。

 Child.hbm.xml：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="org.py.hib.relation.one2many.Child" table="child">
        <id name="id" type="java.lang.String" column="id" length="32" >
            <generator class="uuid" />
        </id>
        <property name="name" type="java.lang.String" column="name" length="128" not-null="true"/>

        <many-to-one name="father" class="org.py.hib.relation.one2many.Father" column="father_id" />
    </class>
</hibernate-mapping>

 这个里面主要就是多了一个many-to-one，表示child 和 father 的关系是"many-to-one"

测试代码如下：

One2ManyTest.java

package org.py.hib.relation.one2many;

import java.util.Set;

import junit.framework.Assert;
import junit.framework.TestCase;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.After;
import org.junit.Before;

public class One2ManyTest extends TestCase
{
	private SessionFactory factory;

	private static final String[] childname = new String[] { "child_1", "child_2", "child_3" };

	private static final String[] newchildname = new String[] { "new_child_1", "new_child_2", "new_child_3" };

	@Before
	public void setUp() throws Exception
	{
		Configuration conf = new Configuration().configure();
		factory = conf.buildSessionFactory();
	}

	/**
	 * 测试添加
	 * @throws Exception
	 */
	public void testSave() throws Exception
	{
		System.out.println("\n=== test save ===");

		Father father = new Father();
		father.setName("Father_1");

		Child child1 = new Child();
		child1.setName(childname[0]);

		Child child2 = new Child();
		child2.setName(childname[1]);

		Child child3 = new Child();
		child3.setName(childname[2]);

		father.getChildren().add(child1);
		father.getChildren().add(child2);
		father.getChildren().add(child3);

		child1.setFather(father);
		child2.setFather(father);
		child3.setFather(father);

		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();
			session.save(father);

			tran.commit();

			Assert.assertNotNull(father.getId());

			Assert.assertNotNull(child1.getId());
			Assert.assertNotNull(child2.getId());
			Assert.assertNotNull(child3.getId());

		} catch (Exception ex)
		{
			tran.rollback();
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	private boolean isChildrenName(String name)
	{
		for (String n : childname)
		{
			if (n.equals(name))
				return true;
		}

		return false;
	}

	private boolean isNewChildrenName(String name)
	{
		for (String n : newchildname)
		{
			if (n.equals(name))
				return true;
		}

		return false;
	}

	/**
	 * 测试查询
	 * @throws Exception
	 */
	public void testFind() throws Exception
	{
		System.out.println("\n=== test find ===");
		Session session = null;
		try
		{
			session = factory.openSession();
			Father father = (Father) session.createQuery("from Father").list().get(0);

			Assert.assertNotNull(father.getId());
			Assert.assertEquals("Father_1", father.getName());

			Set<Child> children = father.getChildren();
			for (Child child : children)
			{
				Assert.assertEquals(child.getFather(), father);

				Assert.assertNotNull(child.getId());

				Assert.assertTrue(isChildrenName(child.getName()));
			}
		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试修改
	 * @throws Exception
	 */
	public void testModify() throws Exception
	{
		System.out.println("\n=== test modify ===");
		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();

			Father father = (Father) session.createQuery("from Father").list().get(0);
			father.setName("Father_2"); // 修改用户名 = m_name2.（原来用户名= m_name）

			Set<Child> children = father.getChildren();
			int i = 0;
			for (Child child : children)
			{
				child.setName(newchildname[i++]);
			}

			tran.commit();

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}

		/*
		 * 修改后再查询
		 */
		System.out.println("\n=== test find after modify ===");
		try
		{
			session = factory.openSession();
			Father father = (Father) session.createQuery("from Father").list().get(0);

			Assert.assertNotNull(father.getId());
			Assert.assertEquals("Father_2", father.getName());

			Set<Child> children = father.getChildren();

			for (Child child : children)
			{
				Assert.assertEquals(child.getFather(), father);

				Assert.assertNotNull(child.getId());

				Assert.assertTrue(isNewChildrenName(child.getName()));
			}

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试删除
	 * @throws Exception
	 */
	public void testDelete() throws Exception
	{
		System.out.println("\n=== test delete ===");
		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();

			Father father = (Father) session.createQuery("from Father").list().get(0);
			session.delete(father);
			tran.commit();

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}

		/*
		 * 删除后再查询
		 */
		System.out.println("\n=== test find after delete ===");
		try
		{
			session = factory.openSession();

			Integer num = (Integer) session.createQuery("from Father").list().size();
			Assert.assertEquals(0, num.intValue());

			num = (Integer) session.createQuery("from Child").list().size();
			Assert.assertEquals(0, num.intValue());

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 
	 */
	@After
	public void tearDown() throws Exception
	{
		factory.close();
	}

}

这里不得不再重申以下 one-to-many 中 inverse 关系的维护问题。 在one-to-many中，把inverse放到many中来维护是一个好的习惯。大家可以把上面的inverse改成false，看看会发生什么情况。

在inverse=true的时候，输出结果如下：

=== test save ===
Hibernate: insert into father (name, id) values (?, ?)
Hibernate: insert into child (name, father_id, id) values (?, ?, ?)
Hibernate: insert into child (name, father_id, id) values (?, ?, ?)
Hibernate: insert into child (name, father_id, id) values (?, ?, ?)

=== test find ===
Hibernate: select father0_.id as id13_, father0_.name as name13_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id14_0_, children0_.name as name14_0_, children0_.father_id as father3_14_0_ from child children0_ where children0_.father_id=?

=== test modify ===
Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id24_0_, children0_.name as name24_0_, children0_.father_id as father3_24_0_ from child children0_ where children0_.father_id=?
Hibernate: update father set name=? where id=?
Hibernate: update child set name=?, father_id=? where id=?
Hibernate: update child set name=?, father_id=? where id=?
Hibernate: update child set name=?, father_id=? where id=?

=== test find after modify ===
Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id24_0_, children0_.name as name24_0_, children0_.father_id as father3_24_0_ from child children0_ where children0_.father_id=?

=== test delete ===
Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id34_0_, children0_.name as name34_0_, children0_.father_id as father3_34_0_ from child children0_ where children0_.father_id=?
Hibernate: delete from child where id=?
Hibernate: delete from child where id=?
Hibernate: delete from child where id=?
Hibernate: delete from father where id=?

=== test find after delete ===
Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_
Hibernate: select child0_.id as id34_, child0_.name as name34_, child0_.father_id as father3_34_ from child child0_

而改成 inverse=false后，testDelete()是没法通过的。输出如下：

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.

=== test save ===
Hibernate: insert into father (name, id) values (?, ?)
Hibernate: insert into child (name, father_id, id) values (?, ?, ?)
Hibernate: insert into child (name, father_id, id) values (?, ?, ?)
Hibernate: insert into child (name, father_id, id) values (?, ?, ?)
Hibernate: update child set father_id=? where id=?
Hibernate: update child set father_id=? where id=?
Hibernate: update child set father_id=? where id=?

=== test find ===
Hibernate: select father0_.id as id13_, father0_.name as name13_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id14_0_, children0_.name as name14_0_, children0_.father_id as father3_14_0_ from child children0_ where children0_.father_id=?

=== test modify ===
Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id24_0_, children0_.name as name24_0_, children0_.father_id as father3_24_0_ from child children0_ where children0_.father_id=?
Hibernate: update father set name=? where id=?
Hibernate: update child set name=?, father_id=? where id=?
Hibernate: update child set name=?, father_id=? where id=?
Hibernate: update child set name=?, father_id=? where id=?

=== test find after modify ===
Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id24_0_, children0_.name as name24_0_, children0_.father_id as father3_24_0_ from child children0_ where children0_.father_id=?

=== test delete ===
Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id34_0_, children0_.name as name34_0_, children0_.father_id as father3_34_0_ from child children0_ where children0_.father_id=?
Hibernate: update child set father_id=null where father_id=?

 错误信息如下：

具体的出错原因是：违反了非空约束。

得修改sql脚本，把Child的建表脚本中的：

                     father_id varchar(32) not null, 修改成为：father_id varchar(32),

才能通过。这个时候输出的结果是：

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.

=== test save ===
Hibernate: insert into father (name, id) values (?, ?)
Hibernate: insert into child (name, father_id, id) values (?, ?, ?)
Hibernate: insert into child (name, father_id, id) values (?, ?, ?)
Hibernate: insert into child (name, father_id, id) values (?, ?, ?)
Hibernate: update child set father_id=? where id=?
Hibernate: update child set father_id=? where id=?
Hibernate: update child set father_id=? where id=?

=== test find ===
Hibernate: select father0_.id as id13_, father0_.name as name13_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id14_0_, children0_.name as name14_0_, children0_.father_id as father3_14_0_ from child children0_ where children0_.father_id=?

=== test modify ===
Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id24_0_, children0_.name as name24_0_, children0_.father_id as father3_24_0_ from child children0_ where children0_.father_id=?
Hibernate: update father set name=? where id=?
Hibernate: update child set name=?, father_id=? where id=?
Hibernate: update child set name=?, father_id=? where id=?
Hibernate: update child set name=?, father_id=? where id=?

=== test find after modify ===
Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id24_0_, children0_.name as name24_0_, children0_.father_id as father3_24_0_ from child children0_ where children0_.father_id=?

=== test delete ===
Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_
Hibernate: select children0_.father_id as father3_1_, children0_.id as id1_, children0_.id as id34_0_, children0_.name as name34_0_, children0_.father_id as father3_34_0_ from child children0_ where children0_.father_id=?
Hibernate: update child set father_id=null where father_id=?
Hibernate: delete from child where id=?
Hibernate: delete from child where id=?
Hibernate: delete from child where id=?
Hibernate: delete from father where id=?

=== test find after delete ===
Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_
Hibernate: select child0_.id as id34_, child0_.name as name34_, child0_.father_id as father3_34_ from child child0_

所以，inverse的设置是很重要的一个事情。

附件中包含了源代码。这里说明一下。源代码中没有包含数据库驱动的jar包和hibernate3.1的jar包。需要大家自己添加。

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接上篇 hibernate入门使用系列 1-- 说明篇+快速构建篇

现在起主要讲 hibernate中的关系映射。对应的关系主要有 1：1， n：1， n：n。今天主要写1：1。

关系映射篇（上）—— 之1：1

1对1的关系在现实中很常见。比方说：人和身份证。1个身份证对应着一个身份证，一个身份证对应着一个人。那么，我们就以此为原型。进行代码编写。

建立实体模型如右：

根据模型，创建数据库：

use HibernateQuickUse;
drop table if exists Person;
drop table if exists Card;

create table Card (
	id varchar(32) primary key,
	cardDesc varchar(128) not null
);

create table Person (
	id varchar(32) primary key,
	name varchar(32) not null,
	card_id varchar(32) not null,
	foreign key(card_id) references Card(id)
);

java代码如下：

Person类

package org.py.hib.relation.one2one;

/**
 * Person entity.
 */

@SuppressWarnings("serial")
public class Person implements java.io.Serializable
{
	private String id;

	private String name;

	private Card card;

	public Person()
	{
	}

	public String getId()
	{
		return this.id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public Card getCard()
	{
		return this.card;
	}

	public void setCard(Card card)
	{
		this.card = card;
	}

	public String getName()
	{
		return this.name;
	}

	public void setName(String name)
	{
		this.name = name;
	}

}

Card类：

package org.py.hib.relation.one2one;

/**
 * Card entity.
 */

@SuppressWarnings("serial")
public class Card implements java.io.Serializable
{
	private String id;

	private String cardDesc;

	public Card()
	{
	}

	public String getId()
	{
		return this.id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public String getCardDesc()
	{
		return cardDesc;
	}

	public void setCardDesc(String cardDesc)
	{
		this.cardDesc = cardDesc;
	}
}

xml映射文件如下：

Person.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
	<class name="org.py.hib.relation.one2one.Person" table="person">
		<id name="id" type="java.lang.String" column="id" length="32">
			<generator class="uuid" />
		</id>

		<property name="name" type="java.lang.String">
			<column name="name" length="32" />
		</property>

		<many-to-one name="card" class="org.py.hib.relation.one2one.Card" unique="true"
			cascade="all" column="card_id" />
			
	</class>
</hibernate-mapping>

今天讲的是one-to-one配置。但是，此处用的是many-to-one，这个是什么原因呢？其实，one-to-one就是特殊的many-to-one。

Card.hbm.xml：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="org.py.hib.relation.one2one.Card" table="card">
        <id name="id" type="java.lang.String" column="id" length="32">
            <generator class="uuid" />
        </id>
        
        <property name="cardDesc" type="java.lang.String" column="cardDesc" length="128" not-null="true"/>

    </class>
</hibernate-mapping>

测试代码如下：

One2OneTest.java

package org.py.hib.relation.one2one;

import junit.framework.Assert;
import junit.framework.TestCase;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.After;
import org.junit.Before;

public class One2OneTest extends TestCase
{
	private SessionFactory factory;

	private String m_name = "ryanpoy";

	private String m_name2 = "ryanpoy2";

	private String m_cardDesc1 = "desc_1";

	private String m_cardDesc2 = "desc_2";

	@Before
	public void setUp() throws Exception
	{
		Configuration conf = new Configuration().configure();
		factory = conf.buildSessionFactory();
	}

	/**
	 * 测试添加
	 * @throws Exception
	 */
	public void testSave() throws Exception
	{
		System.out.println("\n=== test save ===");

		Card card = new Card();
		card.setCardDesc(m_cardDesc1);

		Person person = new Person();
		person.setName(m_name); // 设置用户名 = m_name
		person.setCard(card);

		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();
			session.save(person);
			
			tran.commit();

			Assert.assertEquals(person.getId() != null, true);
			Assert.assertEquals(card.getId() != null, true);

		} catch (Exception ex)
		{
			tran.rollback();
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试查询
	 * @throws Exception
	 */
	public void testFind() throws Exception
	{
		System.out.println("\n=== test find ===");
		Session session = null;
		try
		{
			session = factory.openSession();
			Person person = (Person) session.createQuery("from Person").list().get(0);

			Assert.assertEquals(true, person.getId() != null);
			Assert.assertEquals(m_name, person.getName());

			Assert.assertEquals(true, person.getCard().getId() != null);
			Assert.assertEquals(m_cardDesc1, person.getCard().getCardDesc());

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试修改
	 * @throws Exception
	 */
	public void testModify() throws Exception
	{
		System.out.println("\n=== test modify ===");
		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();

			Person person = (Person) session.createQuery("from Person").list().get(0);
			person.setName(m_name2); // 修改用户名 = m_name2.（原来用户名= m_name）
			person.getCard().setCardDesc(m_cardDesc2); // 修改cardDesc 为 m_cardDesc2 (原来是：m_cardDesc1)
			tran.commit();

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}

		/*
		 * 修改后再查询
		 */
		System.out.println("\n=== test find after modify ===");
		try
		{
			session = factory.openSession();
			Person person = (Person) session.createQuery("from Person").list().get(0);

			Assert.assertEquals(true, person.getId() != null);
			Assert.assertEquals(m_name2, person.getName());

			Assert.assertEquals(true, person.getCard().getId() != null);
			Assert.assertEquals(m_cardDesc2, person.getCard().getCardDesc());

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试删除
	 * @throws Exception
	 */
	public void testDelete() throws Exception
	{
		System.out.println("\n=== test delete ===");
		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();

			Person person = (Person) session.createQuery("from Person").list().get(0);
			session.delete(person);
			tran.commit();

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}

		/*
		 * 删除后再查询
		 */
		System.out.println("\n=== test find after delete ===");
		try
		{
			session = factory.openSession();

			Integer num = (Integer) session.createQuery("from Person").list().size();
			Assert.assertEquals(0, num.intValue());

			num = (Integer) session.createQuery("from Card").list().size();
			Assert.assertEquals(0, num.intValue());

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 
	 */
	@After
	public void tearDown() throws Exception
	{
		factory.close();
	}

}

运行test，一路飚绿。呵呵。陶醉一番。不过，这也就是一个拿不出手的测试和一个拿不出手的例子。没有任何实际意义的例子。仅此一个demo而已。

在1：1中，其实还有一种方式，即：唯一主见关联。但是，我一直倾向于上面的这种形式，所以，唯一主见关联的旧部介绍了。

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写这个 入门使用 系列的文章，算是一个简单的复习吧。

目的1是让没有用过hibernate的工作者们，快速的使用起来。不会介绍太多的深层次的东西。仅仅是一个入门使用而已。


目的2是总结一下hibernate的基本使用，顺便自己再熟悉熟悉。


目的3是交流心得。一个人掌握的东西只有一点点。且掌握的程度有深有浅，如不交流、固步自封，只有被淘汰。欢迎任何人拍砖的。群众的力量是无穷的。在此系列中，难免会有些不恰当或者不对的地方。尽请指出、批评。

对于认为已经熟练掌握hibernate的高手们，可能没有什么用处。但是，无限欢迎交流。

废话不多说，下面开始进入主题。

一. 何谓hibernate？
     答：you can find the answer @google ...

二. 快速构建。
     在此先要说明一下。由于本人懒惰，记不住hibernate的配置选项，所以，此系列的实例都是使用myeclipse进行快速开发。各位对myeclipse不齿的，就请见谅。然后，数据库都是mysql。

下面开始利用hibernate进行数据库的访问。

需求：实现对用户的增、删、改、查。为了方便，用户就2个属性 用户ID和用户名。实体模型如下：



建立工程:HibernateQuickUse，并且建立包。如下：





根据实体，创建类User，代码如下：

package org.py.hib.quickstart;

/**
 * User entity.
 * @author MyEclipse Persistence Tools
 */

@SuppressWarnings("serial")
public class User implements java.io.Serializable
{
	private String id;
	private String name;

	public User()
	{
	}

	public String getId()
	{
		return this.id;
	}

	public void setId(String id)
	{
		this.id = id;
	}

	public String getName()
	{
		return this.name;
	}

	public void setName(String name)
	{
		this.name = name;
	}
}

根据实体，创建数据表。sql如下：

use HibernateQuickUse;
drop table if exists User;

create table user (
	id varchar(32) primary key,
	name varchar(32)
);

这里的id，我没有采用Integer auto_increment, 原因是为了数据库的数据能方便的导入到另外一种数据库里面，比方说：oracle。当然，这个是以牺牲部分效率为前提的。因为id是integer的，能更加快速查询。不过，从数据库会自动为 primary key 建立 index来看，效率也不会相差太多。

要想通过hibernate访问数据库。首先要建立描述数据库的文件：hibernate.cfg.xml。放到src下面。内容如下：

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

	<session-factory>
		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
		<property name="connection.url">jdbc:mysql://localhost:3306/hibernatequickUse</property>
		<property name="connection.username">root</property>
		<property name="connection.password">root</property>
		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
		
		<property name="show_sql">true</property>
		<mapping resource="org/py/hib/quickstart/User.hbm.xml" />

	
	</session-factory>

</hibernate-configuration>

 说说上面的 "dialect", 这个对应着hibernate生成哪种数据库的sql。

 然后是："show_sql", 这个是为了调试时候输出sql语句到屏幕用的。

注意"mapping resource"部分。这个部分表示你的 实体- 数据库 映射文件的位置。（什么是实体-数据库 映射文件，看下面。）

实体-数据库映射文件 -- 主要是告诉hibernate，这个User类，对应着哪个table，User类里面的那个属性对应着table里面的哪个字段。

我们可以建立 实体-数据库 的xml映射文件，也可以采用Annotations映射，但是目前只说xml映射方式。如下：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
	<class name="org.py.hib.quickstart.User" table="user">
                <id name="id" type="java.lang.String" column="id" length="32">
			<generator class="uuid" />
		</id>

		<property name="name"  type="java.lang.String" column="name"	length="32" />
	</class>
</hibernate-mapping>

 上面的xml还是很好理解的。注意一个generator中的class，他可以有很多。我们这用的是uuid。什么是uuid。这个可以google一下。呵呵。google是最好的教科书。还能有很多其他的，比方说：native。具体的同样请教google。

 有了上面的准备，那么我们开始来测试一下。这里我们用junit。具体怎么使用junit，呵呵。答案我想大家都知道了，也不用我说了。其实我对test 和 使用它也不熟练。

我把测试用力放到了test/org.py.hib.quickstart下面。代码如下：

package org.py.hib.quickstart;

import junit.framework.Assert;
import junit.framework.TestCase;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.junit.After;
import org.junit.Before;

public class QuickStartTest extends TestCase
{
	SessionFactory factory;

	String m_name = "ryanpoy";

	String m_name2 = "ryanpoy2";

	@Before
	public void setUp() throws Exception
	{
		Configuration conf = new Configuration().configure();
		factory = conf.buildSessionFactory();
	}

	/**
	 * 测试添加
	 * @throws Exception
	 */
	public void testSave() throws Exception
	{
		System.out.println("\n=== test save ===");
		User u = new User();
		u.setName(m_name); // 设置用户名 = m_name

		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();
			session.save(u);
			tran.commit();

			Assert.assertEquals(u.getId() != null, true);
		} catch (Exception ex)
		{
			tran.rollback();
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试查询
	 * @throws Exception
	 */
	public void testFind() throws Exception
	{
		System.out.println("\n=== test find ===");
		Session session = null;
		try
		{
			session = factory.openSession();
			User u = (User) session.createQuery("from User").list().get(0);

			Assert.assertEquals(true, u.getId() != null);
			Assert.assertEquals(m_name, u.getName());
		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试修改
	 * @throws Exception
	 */
	public void testModify() throws Exception
	{
		System.out.println("\n=== test modify ===");
		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();

			User u = (User) session.createQuery("from User").list().get(0);
			u.setName(m_name2);  // 修改用户名 = m_name2.（原来用户名= m_name）
			tran.commit();

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}

		/*
		 * 修改后再查询
		 */
		System.out.println("\n=== test find after modify ===");
		try
		{
			session = factory.openSession();
			User u = (User) session.createQuery("from User").list().get(0);

			Assert.assertEquals(true, u.getId() != null);
			Assert.assertEquals(m_name2, u.getName());
		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 测试删除
	 * @throws Exception
	 */
	public void testDelete() throws Exception
	{
		System.out.println("\n=== test delete ===");
		Session session = null;
		Transaction tran = null;
		try
		{
			session = factory.openSession();
			tran = session.beginTransaction();

			User u = (User) session.createQuery("from User").list().get(0);
			session.delete(u);
			tran.commit();

		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}

		/*
		 * 删除后再查询
		 */
		System.out.println("\n=== test find after delete ===");
		try
		{
			session = factory.openSession();
			Integer num = (Integer) session.createQuery("from User").list().size();

			Assert.assertEquals(0, num.intValue());
		} catch (Exception ex)
		{
			throw ex;
		} finally
		{
			if (session != null)
			{
				try
				{
					session.close();
				} catch (Exception ex)
				{
					// nothing to do
				} finally
				{
					if (session != null)
						session = null;
				}
			}
		}
	}

	/**
	 * 
	 */
	@After
	public void tearDown() throws Exception
	{
		factory.close();
	}

}

运行后，我们很欣慰的看到一路绿灯，全部通过了。那么测试没有问题。呵呵(这里的测试可能还不完善。请大家指出。前面说过，我对测试这块也不熟)。

看控制台，会输出如下信息：

=== test save ===
Hibernate: insert into hibernatequickuse.user (name, id) values (?, ?)

=== test find ===
Hibernate: select user0_.id as id2_, user0_.name as name2_ from hibernatequickuse.user user0_

=== test modify ===
Hibernate: select user0_.id as id4_, user0_.name as name4_ from hibernatequickuse.user user0_
Hibernate: update hibernatequickuse.user set name=? where id=?

=== test find after modify ===
Hibernate: select user0_.id as id4_, user0_.name as name4_ from hibernatequickuse.user user0_

=== test delete ===
Hibernate: select user0_.id as id6_, user0_.name as name6_ from hibernatequickuse.user user0_
Hibernate: delete from hibernatequickuse.user where id=?

=== test find after delete ===
Hibernate: select user0_.id as id6_, user0_.name as name6_ from hibernatequickuse.user user0_

这些，就是hibernte自动生成的。仔细看看，其实就是标准sql。呵呵。懂jdbc的都能看懂。

好了，第一部分就到这。附件中的zip包是原代码。

    语言的组织，举例的细节似乎像记流水账，看来还是没有文学细胞啊。忘了上次是哪位了，他写的标题就像是看 《圣斗士星矢》一项，激情洋溢啊。

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• 搜狐网站诚聘Java、PHP和C++工程师
• 北京: 千橡集团暨校内网诚聘软件研发工程师
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