mybatis 多对多 处理

下面的例子让新手看不错。可以改进的一点是

          1、不必建立 关联对象实体，可以用map传递两个id进去

          2、文章的resultMap 继承和 查询配置 比较清楚，可以借鉴

 

      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
		ug.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
	  }
	} 
}