Mybatis多對多關聯查詢
阿新 • • 發佈：2018-12-25
mybatis3.0添加了association和collection標籤專門用於對多個相關實體類資料進行級聯查詢，但仍不支援多個相關實體類資料的級聯儲存和級聯刪除操作。因此在進行實體類多對多對映表設計時，需要專門建立一個關聯物件類對相關實體類的關聯關係進行描述。下文將以“User”和“Group”兩個實體類之間的多對多關聯對映為例進行CRUD操作。
建立user表，對應實體類”User”，建表語句如下：
Sql程式碼
CREATE TABLE `user` (
`id` int(11) NOT NULL auto_increment,
`name` 建立group_info表，對應實體類”Group”，建表語句如下：
Sql程式碼
CREATE TABLE `group_info` (
`id` 建立user_group表，對應實體類”UserGroupLink”(該類為User和Group兩個實體類之間的關係描述)，建表語句如下：
Sql程式碼
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`)
) 建立實體類User，程式碼如下：
Java程式碼
package com.xxt.ibatis.dbcp.domain;
import java.util.Date;
import java.util.List;
/**
* @describe: User實體類
* @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;
}
}
建立實體類Group,程式碼如下：
Java程式碼
package com.xxt.ibatis.dbcp.domain;
import java.util.Date;
import java.util.List;
/**
* @describe: Group實體類
* @author: Nirvana
* @version: V1.0 2011-3-7下午08:10:29 create
*/
public class Group {
private long id;
private String name; // 組名
private Date createTime;
private int state; // 0可見狀態 1不可見狀態
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;
}
} 建立實體類UserGroupLink，用於描述User和Group之間的對應關係，程式碼如下：
Java程式碼
package com.xxt.ibatis.dbcp.domain;
import java.util.Date;
/**
* @describe: 描述User和Group之間的對映關係
* @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實體類的對映檔案user.map.xml，程式碼如下：
Xml程式碼
<?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>
<!-- 根據user表中的id查詢使用者資訊 -->
<select id="selectUser" parameterType="long" resultMap="userMap">
select * from user where id = #{id}
</select>
<!-- 根據user表中的id查詢使用者和組資訊 -->
<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>
<!-- 插入使用者資訊 -->
<insert id="saveUser" parameterType="User" keyProperty="id"
useGeneratedKeys="true">
insert into user(name,password) values(#{name},#{password})
</insert>
<!-- 儲存使用者和組之間的關係資訊 -->
<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實體類的對映檔案group.map.xml，程式碼如下:
Xml程式碼
<?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>
<!-- 根據Group表中的id或name查詢組資訊和組內使用者資訊 -->
<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>
<!--當id為初始值0，不再使用id作為查詢條件 -->
<if test="id != 0 ">gi.id=#{id}</if>
<!-- 當name為空或為空串時，不再使用name作為查詢條件 -->
<if test="name != null and name != ''">
or gi.name = #{name}
</if>
</where>
</select>
<!-- 根據id查詢group組資訊 -->
<select id="selectGroup" parameterType="Date"
resultMap="groupMap">
select * from group_info where id=#{group_id}
</select>
<!--根據name查詢group組資訊 -->
<select id="getGroupByName" parameterType="String"
resultMap="groupMap">
select * from group_info where name=#{name}
</select>
<!-- 插入組資訊 -->
<insert id="saveGroup" parameterType="Group" keyProperty="id"
useGeneratedKeys="true">
insert into group_info(name) values(#{name})
</insert>
<!-- 刪除組與組內成員之間的對應關係 -->
<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>
<!--根據組id或者組name刪除組資訊 -->
<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>
<!-- 更新根據組id或者組name更新組狀態 -->
<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Mbatis總配置檔案salMapConfig.xml,程式碼如下：
Xml程式碼
<?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> 測試用例，程式碼如下：
Java程式碼
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: 測試用例
* @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); //讀取ibatis配置檔案
SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);
session = sqlMapper.openSession(true);
session.commit(false); //將預設提交事務屬性設定為否
}
//儲存使用者資訊
@Test
public void saveUserTest(){
User user = new User();
user.setName("張三");
user.setPassword("123456");
session.insert("com.xxt.ibatis.dbcp.domain.User.saveUser", user);
}
//獲取使用者資訊
@Test
public void getUserTest(){
User user = (User) session.selectOne("com.xxt.ibatis.dbcp.domain.User.selectUser", 1L);
System.out.println("使用者名稱： "+user.getName());
System.out.println("使用者密碼: "+user.getPassword());
System.out.println("使用者建立日期："+sdf.format(user.getCreateTime()));
}
//獲取使用者和使用者所在組資訊
@Test
public void getUserAndGroupTest(){
User user = (User)session.selectOne("com.xxt.ibatis.dbcp.domain.User.selectUserGroup", 4L);
System.out.println(user.getName() +"所屬組資訊:");
for(Group group : user.getGroups() ){
System.out.println(" 組名:"+group.getName()+"，組建立時間:"+sdf.format(group.getCreateTime()));
}
}
//儲存使用者和使用者所在組資訊
//當用戶所在組不存在時，建立該組，並生成對映關係
@Test
public void saveUserAndGroupTest(){
User user = new User();
user.setName("無常鬼");
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","使用者組4");//獲取組例項
UserGroupLink ugl = new UserGroupLink();//宣告User和Group實體間對映關係例項
//查詢到的組例項為空時的邏輯處理
if(groupImpl == null){
Group group = new Group();
group.setName("使用者組4");
session.insert("com.xxt.ibatis.dbcp.domain.Group.saveGroup", group);//持久化建立好的組例項
//設定對映關係例項相關的屬性
ugl.setUser(user);
ugl.setGroup(group);
session.insert("com.xxt.ibatis.dbcp.domain.User.saveRelativity",ugl);//持久化對映關係實力
}else{
ugl.setGroup(groupImpl);
ugl.setUser(user);
session.insert("com.xxt.ibatis.dbcp.domain.User.saveRelativity",ugl);
}
}
//刪除組資訊的同時，取消組內所有的成員與該組的關聯關係
@Test
public void deleteGroupTest(){
Group group = new Group();
//group.setId(1L); //以組id作為查詢條件
group.setName("使用者組1"); //以組name作為查詢條件
Group groupImpl = (Group)session.selectOne("com.xxt.ibatis.dbcp.domain.Group.selectGroupUser",group);//獲取組例項
//組例項存在時
if(groupImpl != null){
List<User> users = groupImpl.getUsers();
//檢視使用者組1中是否存在使用者
if(users != null && users.size() > 0){
//存在使用者時，先刪除組與使用者的對應關係
UserGroupLink ugl = new UserGroupLink();
for(User user : users){
ugl.setUser(user);
ugl.setGroup(groupImpl);
session.delete("com.xxt.ibatis.dbcp.domain.Group.deleteGroupUser",ugl );
}
}
//刪除組資訊
session.delete("com.xxt.ibatis.dbcp.domain.Group.deleteGroup", groupImpl);
}else{
throw new RuntimeException("查詢的組不存在!!");
}
}
//更新組狀態，當組狀態由可見狀態變成不可見時，取消該組下的使用者與該組的對映關係
@Test
public void updateGroupStateTest(){
Group group = new Group();
group.setName("使用者組2");
Group groupImpl = (Group) session.selectOne("com.xxt.ibatis.dbcp.domain.Group.selectGroupUser",group);
if(groupImpl != null){
int state = groupImpl.getState() == 1 ? 0 : 1;
//組狀態由0變成1時，即由可見變為不可見
if(state == 1){
List<User> users = groupImpl.getUsers();
//檢視使用者組2中是否存在使用者
if(users != null && users.size() > 0){
//存在使用者時，刪除組與使用者的對應關係
UserGroupLink ugl = new UserGroupLink();
for(User user : users){
ugl.setUser(user);
ugl.setGroup(groupImpl);
session.delete("com.xxt.ibatis.dbcp.domain.Group.deleteGroupUser",ugl );
}
}
}
//更新組狀態
groupImpl.setState(state);
}
else{
throw new RuntimeException("查詢的組不存在!!");
}
}
@AfterClass
public static void tearDownAfterClass() throws Exception {
if(session != null){
session.commit(); //提交事務
session.close(); //關閉連線
}
}
}