myBatis 多对多例子

下本例子可以改进的一点是
          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
  }
} 
}