mybatis3.0多对多映射

mybatis3.0添加了association和collection标签专门用于对多个相关实体类数据进行级联查询，但仍不支持多个相关实体类数据的级联保存和级联删除操作。因此在进行实体类多对多映射表设计时，需要专门建立一个关联对象类对相关实体类的关联关系进行描述。下文将以“User”和“Group"两个实体类之间的多对多关联映射为例进行CRUD操作。

     建立user表，对应实体类"User"，建表语句如下：
     <!--StartFragment-->

 CREATE TABLE `user` (
   `id` int(11) NOT NULL auto_increment,
   `name` varchar(40) collate utf8_unicode_ci default NULL,
   `password` varchar(20) collate utf8_unicode_ci default NULL,
   `createtime` timestamp NULL default CURRENT_TIMESTAMP,
   PRIMARY KEY  (`id`)
 )

 

    建立group_info表，对应实体类"Group"，建表语句如下：

   

 CREATE TABLE `group_info` (
   `id` int(11) NOT NULL auto_increment,
   `name` varchar(40) collate utf8_unicode_ci default NULL,
   `createdate` timestamp NULL default CURRENT_TIMESTAMP,
   `state` int(1) default '0' COMMENT '0:可见;1:不可见',
   PRIMARY KEY  (`id`)
 )

 

   建立user_group表，对应实体类"UserGroupLink"(该类为User和Group两个实体类之间的关系描述)，建表语句如下：

   

 CREATE TABLE `user_group` (
   `user_id` int(11) default NULL,
   `group_id` int(11) default NULL,
   `createdate` timestamp NULL default CURRENT_TIMESTAMP,
   KEY `FK_user_group_user_id` (`user_id`),
   KEY `FK_user_group_group_id` (`group_id`),
   CONSTRAINT `FK_user_group_group_id` FOREIGN KEY (`group_id`) REFERENCES `group_info` (`id`),
   CONSTRAINT `FK_user_group_user_id` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`)
 )

  

   建立实体类User，代码如下：

 package com.xxt.ibatis.dbcp.domain;

 import java.util.Date;
 import java.util.List;

 /**
  * @describe: User实体类
  * @author :    Nirvana
  * @version :   V1.0  2011-3-11下午06:06:49 create
  */

 public class User {

     private long id;

     private String name;

     private String password;

     private Date createTime;

     private List<Group> group;

     public Date getCreateTime() {
         return createTime;
     }

     public void setCreateTime(Date createTime) {
         this.createTime = createTime;
     }

     public long getId() {
         return id;
     }

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

     public String getName() {
         return name;
     }

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

     public String getPassword() {
         return password;
     }

     public void setPassword(String password) {
         this.password = password;
     }

     public List<Group> getGroup() {
         return group;
     }

     public void setGroup(List<Group> group) {
         this.group = group;
     }
 }

  

    建立实体类Group,代码如下：

 package com.xxt.ibatis.dbcp.domain;

 import java.util.Date;
 import java.util.List;

 /**
  * @describe: Group实体类
  * @author : Nirvana
  * @version: V1.0 2011-3-7下午08:10:29 create
  */
 public class Group {

     private long id;

     private String name; // 组名

     private Date createTime;

     private int state; // 0可见状态 1不可见状态

     private List<User> user;

     public Date getCreateTime() {
         return createTime;
     }

     public void setCreateTime(Date createTime) {
         this.createTime = createTime;
     }

     public long getId() {
         return id;
     }

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

     public String getName() {
         return name;
     }

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

     public int getState() {
         return state;
     }

     public void setState(int state) {
         this.state = state;
     }

     public List<User> getUser() {
         return user;
     }

     public void setUser(List<User> user) {
         this.user = user;
     }

 }

 

    建立实体类UserGroupLink，用于描述User和Group之间的对应关系，代码如下：

 package com.xxt.ibatis.dbcp.domain;

 import java.util.Date;

 /**
  * @describe: 描述User和Group之间的映射关系
  * @author: Nirvana
  * @version: V1.0 2011-3-11下午02:57:52 create
  */
 public class UserGroupLink {

     private User user;

     private Group group;

     private Date createTime;

     public Date getCreateTime() {
         return createTime;
     }

     public void setCreateTime(Date createTime) {
         this.createTime = createTime;
     }

     public Group getGroup() {
         return group;
     }

     public void setGroup(Group group) {
         this.group = group;
     }

     public User getUser() {
         return user;
     }

     public void setUser(User user) {
         this.user = user;
     }
 }

    建立user实体类的映射文件user.map.xml，代码如下：

 <?xml version="1.0" encoding="UTF-8" ?>
 <!DOCTYPE mapper
     PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
     "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 <mapper namespace="com.xxt.ibatis.dbcp.domain.User">
     <resultMap type="User" id="userMap">
         <id property="id" column="id" />
         <result property="name" column="name" />
         <result property="password" column="password" />
         <result property="createTime" column="createtime" />
     </resultMap>

     <resultMap type="User" id="userGroupMap" extends="userMap">
         <collection property="groups" ofType="Group">
             <id property="id" column="goupId" />
             <result property="name" column="groupName" />
             <result property="state" column="state" />
             <result property="createTime" column="groupCreateTime" />
         </collection>
     </resultMap>


     <!-- 根据user表中的id查询用户信息 -->
     <select id="selectUser" parameterType="long" resultMap="userMap">
         select * from user where id = #{id}
     </select>

     <!-- 根据user表中的id查询用户和组信息 -->
     <select id="selectUserGroup" parameterType="long"
         resultMap="userGroupMap">
         select u.id,u.name,u.password,u.createtime, gi.id as
         goupId,gi.name as groupName, gi.createdate as groupCreateTime,
         gi.state from user u left join user_group ug on u.id=ug.user_id
         left join group_info gi on ug.group_id=gi.id where u.id = #{id}
     </select>

     <!-- 插入用户信息 -->
     <insert id="saveUser" parameterType="User" keyProperty="id"
         useGeneratedKeys="true">
         insert into user(name,password) values(#{name},#{password})
     </insert>

     <!-- 保存用户和组之间的关系信息 -->
     <insert id="saveRelativity" parameterType="UserGroupLink">
         insert into user_group(user_id,group_id)
         values(#{user.id},#{group.id})
     </insert>

     <select id="selectAllUser" resultMap="userMap">
         select * from user
     </select>

 </mapper>

 

     建立group实体类的映射文件group.map.xml，代码如下:

   

 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE mapper
     PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
     "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 <mapper namespace="com.xxt.ibatis.dbcp.domain.Group">
     <resultMap type="Group" id="groupMap">
         <id property="id" column="id" />
         <result property="name" column="name" />
         <result property="createTime" column="createdate" />
     </resultMap>

     <resultMap type="Group" id="groupUserMap" extends="groupMap">
         <collection property="users" ofType="User">
             <id property="id" column="userId" />
             <result property="name" column="userName" />
             <result property="password" column="password" />
             <result property="createTime" column="userCreateTime" />
         </collection>
     </resultMap>


     <!-- 根据Group表中的id或name查询组信息和组内用户信息 -->
     <select id="selectGroupUser" parameterType="Group"
         resultMap="groupUserMap">
         select u.id as userId,u.name as userName,
         u.password,u.createtime as userCreateTime,
         gi.id,gi.name,gi.createdate,gi.state from group_info gi left
         join user_group ug on gi.id=ug.group_id left join user u on
         uug.user_id=u.id
         <where>
             <!--当id为初始值0，不再使用id作为查询条件 -->
             <if test="id != 0  ">gi.id=#{id}</if>
             <!-- 当name为空或为空串时，不再使用name作为查询条件 -->
             <if test="name != null and name != ''">
                 or gi.name = #{name}
             </if>
         </where>
     </select>

     <!-- 根据id查询group组信息 -->
     <select id="selectGroup" parameterType="Date"
         resultMap="groupMap">
         select * from group_info where id=#{group_id}
     </select>

     <!--根据name查询group组信息  -->
     <select id="getGroupByName" parameterType="String"
         resultMap="groupMap">
         select * from group_info where name=#{name}
     </select>

     <!-- 插入组信息 -->
     <insert id="saveGroup" parameterType="Group" keyProperty="id"
         useGeneratedKeys="true">
         insert into group_info(name) values(#{name})
     </insert>

     <!-- 删除组与组内成员之间的对应关系 -->
     <delete id="deleteGroupUser" parameterType="UserGroupLink">
         delete from user_group
         <where>
             <if test="user.id != 0">user_id = #{user.id}</if>
             <if test="group.id != 0">and group_id = #{group.id}</if>
         </where>
     </delete>

     <!--根据组id或者组name删除组信息 -->
     <delete id="deleteGroup" parameterType="Group">
         delete from group_info
         <where>
             <if test="id!=0">id=#{id}</if>
             <if test="name!=null || name!=''">and name=#{name}</if>
         </where>
     </delete>

     <!-- 更新根据组id或者组name更新组状态 -->
     <update id="updateGroupState" parameterType="Group">
         update group_info set state=#{state}
         <where>
             <if test="id!=0">id=#{id}</if>
             <if test="name!=null || name!=''">and name=#{name}</if>
         </where>
     </update>
 </mapper>

    建立ibatis总配置文件salMapConfig.xml,代码如下：

  

 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE configuration
     PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
     "http://mybatis.org/dtd/mybatis-3-config.dtd">
 <configuration>
     <properties resource="jdbc.properties" />

     <typeAliases>
         <typeAlias type="com.xxt.ibatis.dbcp.domain.User" alias="User" />
         <typeAlias type="com.xxt.ibatis.dbcp.domain.Group"
             alias="Group" />
         <typeAlias type="com.xxt.ibatis.dbcp.domain.UserGroupLink"
             alias="UserGroupLink" />
     </typeAliases>

     <environments default="development">
         <environment id="development">
             <transactionManager type="JDBC" />
             <dataSource type="UNPOOLED">
                 <property name="driver" value="${driver}" />
                 <property name="url" value="${url}" />
                 <property name="username" value="${username}" />
                 <property name="password" value="${password}" />
             </dataSource>
         </environment>
     </environments>

     <mappers>
         <mapper resource="com/xxt/ibatis/dbcp/domain/user.map.xml" />
         <mapper resource="com/xxt/ibatis/dbcp/domain/group.map.xml" />
     </mappers>
 </configuration>

    测试用例，代码如下：

   

 package com.xxt.ibatis.dbcp.test;

 import java.io.Reader;
 import java.text.SimpleDateFormat;
 import java.util.List;

 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;

 import org.apache.ibatis.io.Resources;
 import org.apache.ibatis.session.SqlSession;
 import org.apache.ibatis.session.SqlSessionFactory;
 import org.apache.ibatis.session.SqlSessionFactoryBuilder;

 import com.xxt.ibatis.dbcp.domain.Group;
 import com.xxt.ibatis.dbcp.domain.User;
 import com.xxt.ibatis.dbcp.domain.UserGroupLink;

 /**
  * @describe: 测试用例
  * @author:    Nirvana
  * @version:   V1.0  2011-3-4下午03:21:17 create
  */
 public class IbatisUserTest {

     private final static String IBATIS_CONFIG_XML  = "sqlMapConfig.xml";
     private static SqlSession session;
     private SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd k:mm:ss");

     @BeforeClass
     public static void setUpBeforeClass() throws Exception {
          Reader reader = Resources.getResourceAsReader(IBATIS_CONFIG_XML);  //读取ibatis配置文件
          SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);
           session = sqlMapper.openSession(true);
           session.commit(false); //将默认提交事务属性设置为否
     }


     //保存用户信息
     @Test
     public void saveUserTest(){
         User user = new User();
         user.setName("张三");
         user.setPassword("123456");
         session.insert("com.xxt.ibatis.dbcp.domain.User.saveUser", user);
     }

     //获取用户信息
     @Test
     public void getUserTest(){
         User user = (User) session.selectOne("com.xxt.ibatis.dbcp.domain.User.selectUser", 1L);
         System.out.println("用户名： "+user.getName());
         System.out.println("用户密码:  "+user.getPassword());
         System.out.println("用户创建日期："+sdf.format(user.getCreateTime()));
     }

     //获取用户和用户所在组信息
     @Test
     public void getUserAndGroupTest(){
          User  user =  (User)session.selectOne("com.xxt.ibatis.dbcp.domain.User.selectUserGroup", 4L);

          System.out.println(user.getName() +"所属组信息:");
         for(Group group : user.getGroups() ){
             System.out.println("    组名:"+group.getName()+"，组创建时间:"+sdf.format(group.getCreateTime()));
         }


     }

     //保存用户和用户所在组信息
     //当用户所在组不存在时，创建该组，并生成映射关系
     @Test
     public void saveUserAndGroupTest(){
         User user = new User();
         user.setName("无常鬼");
         user.setPassword("wuchang");
         session.insert("com.xxt.ibatis.dbcp.domain.User.saveUser", user);

         Group groupImpl = (Group)session.selectOne("com.xxt.ibatis.dbcp.domain.Group.getGroupByName","用户组4");//获取组实例
         UserGroupLink ugl = new UserGroupLink();//声明User和Group实体间映射关系实例

         //查询到的组实例为空时的逻辑处理
         if(groupImpl == null){
              Group group = new Group();
              group.setName("用户组4");
             session.insert("com.xxt.ibatis.dbcp.domain.Group.saveGroup", group);//持久化创建好的组实例

             //设置映射关系实例相关的属性
             ugl.setUser(user);
             ugl.setGroup(group);
             session.insert("com.xxt.ibatis.dbcp.domain.User.saveRelativity",ugl);//持久化映射关系实力

         }else{
             ugl.setGroup(groupImpl);
             ugl.setUser(user);
             session.insert("com.xxt.ibatis.dbcp.domain.User.saveRelativity",ugl);
         }
     }


     //删除组信息的同时，取消组内所有的成员与该组的关联关系
     @Test
     public void deleteGroupTest(){
         Group group = new Group();
         //group.setId(1L);  //以组id作为查询条件
         group.setName("用户组1"); //以组name作为查询条件
         Group groupImpl = (Group)session.selectOne("com.xxt.ibatis.dbcp.domain.Group.selectGroupUser",group);//获取组实例

         //组实例存在时
         if(groupImpl != null){

             List<User> users = groupImpl.getUsers();

           //查看用户组1中是否存在用户
             if(users != null && users.size() > 0){

                 //存在用户时，先删除组与用户的对应关系
                 UserGroupLink ugl = new UserGroupLink();
                 for(User user : users){
                    ugl.setUser(user);
                    ugl.setGroup(groupImpl);
                    session.delete("com.xxt.ibatis.dbcp.domain.Group.deleteGroupUser",ugl );
                 }
             }
             //删除组信息
             session.delete("com.xxt.ibatis.dbcp.domain.Group.deleteGroup", groupImpl);

         }else{
             throw new RuntimeException("查询的组不存在!!");
         }


     }


     //更新组状态，当组状态由可见状态变成不可见时，取消该组下的用户与该组的映射关系
     @Test
     public void updateGroupStateTest(){
         Group group = new Group();
         group.setName("用户组2");
         Group groupImpl = (Group) session.selectOne("com.xxt.ibatis.dbcp.domain.Group.selectGroupUser",group);

         if(groupImpl != null){
             int state = groupImpl.getState() == 1 ? 0 : 1;


             //组状态由0变成1时，即由可见变为不可见
             if(state == 1){
                 List<User> users = groupImpl.getUsers();
            //查看用户组2中是否存在用户
                 if(users != null && users.size() > 0){

                     //存在用户时，删除组与用户的对应关系
                     UserGroupLink ugl = new UserGroupLink();
                     for(User user : users){
                        ugl.setUser(user);
                        ugl.setGroup(groupImpl);
                        session.delete("com.xxt.ibatis.dbcp.domain.Group.deleteGroupUser",ugl );
                     }
                 }
             }

             //更新组状态
             groupImpl.setState(state);
         }
         else{
             throw new RuntimeException("查询的组不存在!!");
         }

     }

     @AfterClass
     public static void tearDownAfterClass() throws Exception {
       if(session != null){
          session.commit(); //提交事务
          session.close(); //关闭连接
       }
     }
 }

 

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• 2011-03-14 19:52
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评论

2 楼  java-lxm 2011-11-02  

郁闷，中间表的字段呢

1 楼  LanderRooter 2011-08-22  

楼主，您好， 

public class UserGroupLink {   
  
    private User user;   
  
    private Group group;   
  
    private Date createTime;   
    ..... 
} 

 <resultMap type="User" id="userMap">
     <id property="id" column="id" />
     <result property="name" column="name" />
     <result property="password" column="password" />
     <result property="createTime" column="createtime" />
 </resultMap>

 <resultMap type="User" id="userGroupMap" extends="userMap">
     <collection property="groups" ofType="Group">
         <id property="id" column="goupId" />
         <result property="name" column="groupName" />
         <result property="state" column="state" />
         <result property="createTime" column="[b]groupCreateTime[/b]" />
     </collection>
 </resultMap>

文章中如上的映射，并没有将UserGroupLink的createDate映射到UserGroupLink，而是把groupCreateTime映射到Group的createTime属性 

 <select id="selectUserGroup" parameterType="long"
     resultMap="userGroupMap">
     select u.id,u.name,u.password,u.createtime, gi.id as
     goupId,gi.name as groupName, gi.createdate as [b]groupCreateTime[/b],
     gi.state from user u left join user_group ug on u.id=ug.user_id
     left join group_info gi on ug.group_id=gi.id where u.id = #{id}
 </select>

关联对象类UserGroupLink中的createTime属性该如何映射呢，在此例中并没有把UserGroupLink的createTime 映射出来，如果此关联对象类还有boolean enable等属性，可不可以直接将结果映射成UserGroupLink呢？，如何可以的话，该如何映射呢，谢谢。小弟最近在项目中要Mybatis,也遇到类似的case，不是很清楚如何解决，谢谢。