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hibernate入门使用系列 3-- xml关系映射篇（中）

接上篇 hibernate入门使用系列 2-- xml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：

1. use HibernateQuickUse;   
2. drop table if exists Child;   
3. drop table if exists Father;   
4.   
5. create table Father (   
6.     id varchar(32) primary key,   
7.     name varchar(32) not null  
8. );   
9.   
10. create table Child (   
11.     id varchar(32) primary key,   
12.     name varchar(128) not null,   
13.     father_id varchar(32) not null,   
14.     foreign key(father_id) references Father(id)   
15. );  

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：

1. package org.py.hib.relation.one2many;   
2.   
3. import java.util.HashSet;   
4. import java.util.Set;   
5.   
6. /**  
7.  * Father entity.  
8.  */  
9.   
10. @SuppressWarnings("serial")   
11. public class Father implements java.io.Serializable   
12. {   
13.     private String id;   
14.   
15.     private String name;   
16.   
17.     private Set children = new HashSet(0);   
18.   
19.     public Father()   
20.     {   
21.     }   
22.   
23.     public String getId()   
24.     {   
25.         return this.id;   
26.     }   
27.   
28.     public void setId(String id)   
29.     {   
30.         this.id = id;   
31.     }   
32.   
33.     public String getName()   
34.     {   
35.         return this.name;   
36.     }   
37.   
38.     public void setName(String name)   
39.     {   
40.         this.name = name;   
41.     }   
42.   
43.     public Set getChildren()   
44.     {   
45.         return children;   
46.     }   
47.   
48.     public void setChildren(Set children)   
49.     {   
50.         this.children = children;   
51.     }   
52. }  

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 children = new HashSet(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 getChildren(){return children;}public void setChildren(Set children){this.children = children;}}

 Child.java：

1. package org.py.hib.relation.one2many;   
2.   
3. /**  
4.  * Child entity.  
5.  * @author MyEclipse Persistence Tools  
6.  */  
7.   
8. @SuppressWarnings("serial")   
9. public class Child implements java.io.Serializable   
10. {   
11.     private String id;   
12.   
13.     private String name;   
14.   
15.     private Father father;   
16.   
17.     public Child()   
18.     {   
19.     }   
20.   
21.     public String getId()   
22.     {   
23.         return this.id;   
24.     }   
25.   
26.     public void setId(String id)   
27.     {   
28.         this.id = id;   
29.     }   
30.   
31.     public Father getFather()   
32.     {   
33.         return this.father;   
34.     }   
35.   
36.     public void setFather(Father father)   
37.     {   
38.         this.father = father;   
39.     }   
40.   
41.     public String getName()   
42.     {   
43.         return this.name;   
44.     }   
45.   
46.     public void setName(String name)   
47.     {   
48.         this.name = name;   
49.     }   
50.   
51. }  

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：

1.  version="1.0" encoding="utf-8"?>  
3. "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">  
4.   
5.   
6.      name="org.py.hib.relation.one2many.Father" table="father">  
7.          name="id" type="java.lang.String" column="id" length="32">  
8.              class="uuid" />  
9.           
10.   
11.          name="name" type="java.lang.String" column="name" length="32" not-null="true"/>  
12.            
13.      name="children" table="child" cascade="all" inverse="true">  
14.              column="father_id" />  
15.              class="org.py.hib.relation.one2many.Child" />  
16.           
17.       
18.   

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：

Java代码  

1. "1.0" encoding="utf-8"?>   
2. "-//Hibernate/Hibernate Mapping DTD 3.0//EN"  
3. "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">   
4.   
5.   
6.     <class name="org.py.hib.relation.one2many.Child" table="child">   
7.         "id" type="java.lang.String" column="id" length="32" >   
8.             class="uuid" />   
9.            
10.         "name" type="java.lang.String" column="name" length="128" not-null="true"/>   
11.   
12.         "father" class="org.py.hib.relation.one2many.Father" column="father_id" />   
13.     class>   
14.   

 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

1. package org.py.hib.relation.one2many;   
2.   
3. import java.util.Set;   
4.   
5. import junit.framework.Assert;   
6. import junit.framework.TestCase;   
7.   
8. import org.hibernate.Session;   
9. import org.hibernate.SessionFactory;   
10. import org.hibernate.Transaction;   
11. import org.hibernate.cfg.Configuration;   
12. import org.junit.After;   
13. import org.junit.Before;   
14.   
15. public class One2ManyTest extends TestCase   
16. {   
17.     private SessionFactory factory;   
18.   
19.     private static final String[] childname = new String[] { "child_1", "child_2", "child_3" };   
20.   
21.     private static final String[] newchildname = new String[] { "new_child_1", "new_child_2", "new_child_3" };   
22.   
23.     @Before  
24.     public void setUp() throws Exception   
25.     {   
26.         Configuration conf = new Configuration().configure();   
27.         factory = conf.buildSessionFactory();   
28.     }   
29.   
30.     /**  
31.      * 测试添加  
32.      * @throws Exception  
33.      */  
34.     public void testSave() throws Exception   
35.     {   
36.         System.out.println("\n=== test save ===");   
37.   
38.         Father father = new Father();   
39.         father.setName("Father_1");   
40.   
41.         Child child1 = new Child();   
42.         child1.setName(childname[0]);   
43.   
44.         Child child2 = new Child();   
45.         child2.setName(childname[1]);   
46.   
47.         Child child3 = new Child();   
48.         child3.setName(childname[2]);   
49.   
50.         father.getChildren().add(child1);   
51.         father.getChildren().add(child2);   
52.         father.getChildren().add(child3);   
53.   
54.         child1.setFather(father);   
55.         child2.setFather(father);   
56.         child3.setFather(father);   
57.   
58.         Session session = null;   
59.         Transaction tran = null;   
60.         try  
61.         {   
62.             session = factory.openSession();   
63.             tran = session.beginTransaction();   
64.             session.save(father);   
65.   
66.             tran.commit();   
67.   
68.             Assert.assertNotNull(father.getId());   
69.   
70.             Assert.assertNotNull(child1.getId());   
71.             Assert.assertNotNull(child2.getId());   
72.             Assert.assertNotNull(child3.getId());   
73.   
74.         } catch (Exception ex)   
75.         {   
76.             tran.rollback();   
77.             throw ex;   
78.         } finally  
79.         {   
80.             if (session != null)   
81.             {   
82.                 try  
83.                 {   
84.                     session.close();   
85.                 } catch (Exception ex)   
86.                 {   
87.                     // nothing to do   
88.                 } finally  
89.                 {   
90.                     if (session != null)   
91.                         session = null;   
92.                 }   
93.             }   
94.         }   
95.     }   
96.   
97.     private boolean isChildrenName(String name)   
98.     {   
99.         for (String n : childname)   
100.         {   
101.             if (n.equals(name))   
102.                 return true;   
103.         }   
104.   
105.         return false;   
106.     }   
107.   
108.     private boolean isNewChildrenName(String name)   
109.     {   
110.         for (String n : newchildname)   
111.         {   
112.             if (n.equals(name))   
113.                 return true;   
114.         }   
115.   
116.         return false;   
117.     }   
118.   
119.     /**  
120.      * 测试查询  
121.      * @throws Exception  
122.      */  
123.     public void testFind() throws Exception   
124.     {   
125.         System.out.println("\n=== test find ===");   
126.         Session session = null;   
127.         try  
128.         {   
129.             session = factory.openSession();   
130.             Father father = (Father) session.createQuery("from Father").list().get(0);   
131.   
132.             Assert.assertNotNull(father.getId());   
133.             Assert.assertEquals("Father_1", father.getName());   
134.   
135.             Set children = father.getChildren();   
136.             for (Child child : children)   
137.             {   
138.                 Assert.assertEquals(child.getFather(), father);   
139.   
140.                 Assert.assertNotNull(child.getId());   
141.   
142.                 Assert.assertTrue(isChildrenName(child.getName()));   
143.             }   
144.         } catch (Exception ex)   
145.         {   
146.             throw ex;   
147.         } finally  
148.         {   
149.             if (session != null)   
150.             {   
151.                 try  
152.                 {   
153.                     session.close();   
154.                 } catch (Exception ex)   
155.                 {   
156.                     // nothing to do   
157.                 } finally  
158.                 {   
159.                     if (session != null)   
160.                         session = null;   
161.                 }   
162.             }   
163.         }   
164.     }   
165.   
166.     /**  
167.      * 测试修改  
168.      * @throws Exception  
169.      */  
170.     public void testModify() throws Exception   
171.     {   
172.         System.out.println("\n=== test modify ===");   
173.         Session session = null;   
174.         Transaction tran = null;   
175.         try  
176.         {   
177.             session = factory.openSession();   
178.             tran = session.beginTransaction();   
179.   
180.             Father father = (Father) session.createQuery("from Father").list().get(0);   
181.             father.setName("Father_2"); // 修改用户名 = m_name2.（原来用户名= m_name）   
182.   
183.             Set children = father.getChildren();   
184.             int i = 0;   
185.             for (Child child : children)   
186.             {   
187.                 child.setName(newchildname[i++]);   
188.             }   
189.   
190.             tran.commit();   
191.   
192.         } catch (Exception ex)   
193.         {   
194.             throw ex;   
195.         } finally  
196.         {   
197.             if (session != null)   
198.             {   
199.                 try  
200.                 {   
201.                     session.close();   
202.                 } catch (Exception ex)   
203.                 {   
204.                     // nothing to do   
205.                 } finally  
206.                 {   
207.                     if (session != null)   
208.                         session = null;   
209.                 }   
210.             }   
211.         }   
212.   
213.         /*  
214.          * 修改后再查询  
215.          */  
216.         System.out.println("\n=== test find after modify ===");   
217.         try  
218.         {   
219.             session = factory.openSession();   
220.             Father father = (Father) session.createQuery("from Father").list().get(0);   
221.   
222.             Assert.assertNotNull(father.getId());   
223.             Assert.assertEquals("Father_2", father.getName());   
224.   
225.             Set children = father.getChildren();   
226.   
227.             for (Child child : children)   
228.             {   
229.                 Assert.assertEquals(child.getFather(), father);   
230.   
231.                 Assert.assertNotNull(child.getId());   
232.   
233.                 Assert.assertTrue(isNewChildrenName(child.getName()));   
234.             }   
235.   
236.         } catch (Exception ex)   
237.         {   
238.             throw ex;   
239.         } finally  
240.         {   
241.             if (session != null)   
242.             {   
243.                 try  
244.                 {   
245.                     session.close();   
246.                 } catch (Exception ex)   
247.                 {   
248.                     // nothing to do   
249.                 } finally  
250.                 {   
251.                     if (session != null)   
252.                         session = null;   
253.                 }   
254.             }   
255.         }   
256.     }   
257.   
258.     /**  
259.      * 测试删除  
260.      * @throws Exception  
261.      */  
262.     public void testDelete() throws Exception   
263.     {   
264.         System.out.println("\n=== test delete ===");   
265.         Session session = null;   
266.         Transaction tran = null;   
267.         try  
268.         {   
269.             session = factory.openSession();   
270.             tran = session.beginTransaction();   
271.   
272.             Father father = (Father) session.createQuery("from Father").list().get(0);   
273.             session.delete(father);   
274.             tran.commit();   
275.   
276.         } catch (Exception ex)   
277.         {   
278.             throw ex;   
279.         } finally  
280.         {   
281.             if (session != null)   
282.             {   
283.                 try  
284.                 {   
285.                     session.close();   
286.                 } catch (Exception ex)   
287.                 {   
288.                     // nothing to do   
289.                 } finally  
290.                 {   
291.                     if (session != null)   
292.                         session = null;   
293.                 }   
294.             }   
295.         }   
296.   
297.         /*  
298.          * 删除后再查询  
299.          */  
300.         System.out.println("\n=== test find after delete ===");   
301.         try  
302.         {   
303.             session = factory.openSession();   
304.   
305.             Integer num = (Integer) session.createQuery("from Father").list().size();   
306.             Assert.assertEquals(0, num.intValue());   
307.   
308.             num = (Integer) session.createQuery("from Child").list().size();   
309.             Assert.assertEquals(0, num.intValue());   
310.   
311.         } catch (Exception ex)   
312.         {   
313.             throw ex;   
314.         } finally  
315.         {   
316.             if (session != null)   
317.             {   
318.                 try  
319.                 {   
320.                     session.close();   
321.                 } catch (Exception ex)   
322.                 {   
323.                     // nothing to do   
324.                 } finally  
325.                 {   
326.                     if (session != null)   
327.                         session = null;   
328.                 }   
329.             }   
330.         }   
331.     }   
332.   
333.     /**  
334.      *   
335.      */  
336.     @After  
337.     public void tearDown() throws Exception   
338.     {   
339.         factory.close();   
340.     }   
341.   
342. }  

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" };@Beforepublic 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 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 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 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;}}}}/****/@Afterpublic 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：

1. === test save ===   
2. Hibernate: insert into father (name, id) values (?, ?)   
3. Hibernate: insert into child (name, father_id, id) values (?, ?, ?)   
4. Hibernate: insert into child (name, father_id, id) values (?, ?, ?)   
5. Hibernate: insert into child (name, father_id, id) values (?, ?, ?)   
6.   
7. === test find ===   
8. Hibernate: select father0_.id as id13_, father0_.name as name13_ from father father0_   
9. 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=?   
10.   
11. === test modify ===   
12. Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_   
13. 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=?   
14. Hibernate: update father set name=? where id=?   
15. Hibernate: update child set name=?, father_id=? where id=?   
16. Hibernate: update child set name=?, father_id=? where id=?   
17. Hibernate: update child set name=?, father_id=? where id=?   
18.   
19. === test find after modify ===   
20. Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_   
21. 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=?   
22.   
23. === test delete ===   
24. Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_   
25. 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=?   
26. Hibernate: delete from child where id=?   
27. Hibernate: delete from child where id=?   
28. Hibernate: delete from child where id=?   
29. Hibernate: delete from father where id=?   
30.   
31. === test find after delete ===   
32. Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_   
33. Hibernate: select child0_.id as id34_, child0_.name as name34_, child0_.father_id as father3_34_ from child child0_  

=== 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：

1. log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).   
2. log4j:WARN Please initialize the log4j system properly.   
3.   
4. === test save ===   
5. Hibernate: insert into father (name, id) values (?, ?)   
6. Hibernate: insert into child (name, father_id, id) values (?, ?, ?)   
7. Hibernate: insert into child (name, father_id, id) values (?, ?, ?)   
8. Hibernate: insert into child (name, father_id, id) values (?, ?, ?)   
9. Hibernate: update child set father_id=? where id=?   
10. Hibernate: update child set father_id=? where id=?   
11. Hibernate: update child set father_id=? where id=?   
12.   
13. === test find ===   
14. Hibernate: select father0_.id as id13_, father0_.name as name13_ from father father0_   
15. 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=?   
16.   
17. === test modify ===   
18. Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_   
19. 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=?   
20. Hibernate: update father set name=? where id=?   
21. Hibernate: update child set name=?, father_id=? where id=?   
22. Hibernate: update child set name=?, father_id=? where id=?   
23. Hibernate: update child set name=?, father_id=? where id=?   
24.   
25. === test find after modify ===   
26. Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_   
27. 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=?   
28.   
29. === test delete ===   
30. Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_   
31. 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=?   
32. Hibernate: update child set father_id=null where father_id=?  

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：

1. log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).   
2. log4j:WARN Please initialize the log4j system properly.   
3.   
4. === test save ===   
5. Hibernate: insert into father (name, id) values (?, ?)   
6. Hibernate: insert into child (name, father_id, id) values (?, ?, ?)   
7. Hibernate: insert into child (name, father_id, id) values (?, ?, ?)   
8. Hibernate: insert into child (name, father_id, id) values (?, ?, ?)   
9. Hibernate: update child set father_id=? where id=?   
10. Hibernate: update child set father_id=? where id=?   
11. Hibernate: update child set father_id=? where id=?   
12.   
13. === test find ===   
14. Hibernate: select father0_.id as id13_, father0_.name as name13_ from father father0_   
15. 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=?   
16.   
17. === test modify ===   
18. Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_   
19. 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=?   
20. Hibernate: update father set name=? where id=?   
21. Hibernate: update child set name=?, father_id=? where id=?   
22. Hibernate: update child set name=?, father_id=? where id=?   
23. Hibernate: update child set name=?, father_id=? where id=?   
24.   
25. === test find after modify ===   
26. Hibernate: select father0_.id as id23_, father0_.name as name23_ from father father0_   
27. 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=?   
28.   
29. === test delete ===   
30. Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_   
31. 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=?   
32. Hibernate: update child set father_id=null where father_id=?   
33. Hibernate: delete from child where id=?   
34. Hibernate: delete from child where id=?   
35. Hibernate: delete from child where id=?   
36. Hibernate: delete from father where id=?   
37.   
38. === test find after delete ===   
39. Hibernate: select father0_.id as id33_, father0_.name as name33_ from father father0_   
40. Hibernate: select child0_.id as id34_, child0_.name as name34_, child0_.father_id as father3_34_ from child child0_  

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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