懂hibernate请进【外键出错】…

[过往记忆]

下面是我的文件：

package com.wyp.bbs.hibernate.DB;

// Generated 2010-5-3 12:33:31 by Hibernate Tools 3.2.0.b9

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

/**
 * User generated by hbm2java
 */
public class User implements java.io.Serializable {

	private int id;

	private Headsculpture headsculpture;//头像

	private String name;

		public User() {
	}

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

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

	public Headsculpture getHeadsculpture() {
		return this.headsculpture;
	}

	public void setHeadsculpture(Headsculpture headsculpture) {
		this.headsculpture = headsculpture;
	}

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

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

	}

上面的是user类，他和user表对应，user表的headpic和headsculpture表中的Hpath是关联的，

<?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="com.wyp.bbs.hibernate.DB.User" table="user" catalog="bbs">
        <id name="id" type="java.lang.Integer">
            <column name="Id" />
            <generator class="identity" />
        </id>
        <many-to-one name="headsculpture" class="com.wyp.bbs.hibernate.DB.Headsculpture" fetch="select" >
            <column name="headpic" />
        </many-to-one>
        <property name="name" type="java.lang.String">
            <column name="name" not-null="true" />
        </property>
     </class>
</hibernate-mapping>

Headsculpture 类

package com.wyp.bbs.hibernate.DB;

// Generated 2010-5-3 12:33:31 by Hibernate Tools 3.2.0.b9

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

/**
 * Headsculpture generated by hbm2java
 */
public class Headsculpture  {

	private int id;

	private String hpath;


	private Set users = new HashSet(0);

	public Headsculpture() {
	}

	

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

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

	public String getHpath() {
		return this.hpath;
	}

	public void setHpath(String hpath) {
		this.hpath = hpath;
	}

	

	public Set getUsers() {
		return this.users;
	}

	public void setUsers(Set users) {
		this.users = users;
	}

}

Headsculpture 的配置

<?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="com.wyp.bbs.hibernate.DB.Headsculpture" table="headsculpture" catalog="bbs">
        <id name="id" type="java.lang.Integer">
            <column name="Id" />
            <generator class="identity" />
        </id>
        <property name="hpath" type="java.lang.String">
            <column name="Hpath" not-null="true" />
        </property>
        
        <set name="users" inverse="true" >
            <key>
                <column name="headpic" />
            </key>
            <one-to-many class="com.wyp.bbs.hibernate.DB.User" />
        </set>
       
    </class>
</hibernate-mapping>

下面是测试类

package com.wyp.bbs.Impl;

import java.io.UnsupportedEncodingException;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import com.wyp.bbs.hibernate.DB.Headsculpture;
import com.wyp.bbs.hibernate.DB.HeadsculptureDAO;
import com.wyp.bbs.hibernate.DB.UserDAO;

import com.wyp.bbs.hibernate.DB.User;


public class UserClient {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		UserDAO userDao = new UserDAO() ;
		
		User user = new User() ;
				
		HeadsculptureDAO Dao = new HeadsculptureDAO();
		
		List list = Dao.findByHpath("default.gif") ;
		
		Headsculpture headPic =(Headsculpture)list.get(0); 
		
		user.setHeadsculpture(headPic);
		
		System.out.println(headPic.getHpath());
		user.setName("wyp") ;
		userDao.save(user) ;

	}

}

上面的代码运行时出现下面的错误
Caused by: java.sql.SQLException: Duplicate key or integrity constraint violation message from server: "Cannot add or update a child row: a foreign key constraint fails (`bbs`.`user`, CONSTRAINT `FK_user_1` FOREIGN KEY (`headpic`) REFERENCES `headsculpture` (`Hpath`) ON DELETE SET NULL ON UPDATE SET NULL)"
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:1997)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1167)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1278)
at com.mysql.jdbc.Connection.execSQL(Connection.java:2251)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1772)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1619)
at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:73)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:33)
... 17 more
这是怎么回事啊？？

[过往记忆]

你回复的留言我看了一下，我也和那上面的一样配置来一下，但是还是不行

[hoojo]

<id name="id" type="java.lang.Integer">
            <column name="Id" />
            <generator class="identity" />
        </id>
将主键设置成String型的uuid增长模式，因为identity用的是数据库的自增策略。
所以要在插入以后才能生产id，而uuid则是通过hiberntate自动生产的唯一id。

[xiaomaha]

cascade="all"

[BearKin]

只保存USER的话会不会有问题？ 如果还有问题把一对多的配置去掉 光是多对一有没有问题？

[swit1983]

没问题。

[过往记忆]

单个类是没有关系的，因为但各类就会成功，但是连上外键就不行，老是出现外键重复

[BearKin]

检查下记录 首先你把数据库的记录全部删除 然后做次更新操作是否好使 然后检查下你那个列是怎么回事

[BearKin]

<key foreign-key="id">
<column name="headpic" />
</key>

[xiaomaha]

cascade="all" 或 save-update 级联关系，你根据图片名字读取到信息，然后修改，然后在save? User,User和Headsculpture 有关联关系，所以你保存user的时候应该进行关联操作！
你式下！写出来那么久没式过么？

[xiaomaha]

cascade="all" 或 save-update 级联关系，你根据图片名字读取到信息，然后在新增加一个用户， User和Headsculpture 有关联关系，所以你保存user的时候应该进行关联操作！
写出来那么久为什么不试呢？

[过往记忆]

呵呵，不是我没有去操作，我已经修改了好多次数，还是出现那样的异常。

[过往记忆]

这个异常我还真是无语，弄了好久，还是没有解决啊？？呵呵……希望大家帮帮啊！！急救啊！！5555555

[bb100044535]

<many-to-one name="headsculpture" class="com.wyp.bbs.hibernate.DB.Headsculpture" fetch="select" >
<column name="headpic" />
</many-to-one>

应改成：
<many-to-one name="headsculpture" class="com.wyp.bbs.hibernate.DB.Headsculpture" fetch="select" >
<column name="Id" />
</many-to-one>

还有
<set name="users" inverse="true" >
<key>
<column name="headpic" />
</key>
<one-to-many class="com.wyp.bbs.hibernate.DB.User" />
</set>
应该为：
<set name="users" inverse="true" >
<key>
<column name="Id" />
</key>
<one-to-many class="com.wyp.bbs.hibernate.DB.User" />
</set>

你要配多对一或一对多要记得配上主表"headsculpture"的id即“Id”
试试看

[bb100044535]

还有，有必要时要配上延时加载
即把lazy=“false”配上

[swit1983]

主键生成策略还是用incriment比较好吧。确保user表中的headpic字段对应pic表中的主键。