Java基础-SSM之mybatis的树形控件（自关联）

　　　　　　　　　　　Java基础-SSM之mybatis的树形控件（自关联）

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　作者：尹正杰

版权声明：原创作品，谢绝转载！否则将追究法律责任。

一.准备测试环境（创建数据库表）

1>.创建areas表；

use yinzhengjie;

create table areas(id int primary key auto_increment , areaname varchar(30) , pid int) ;

 2>.添加Maven依赖

 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>cn.org.yinzhengjie</groupId>
     <artifactId>Mybatis</artifactId>
     <version>1.0-SNAPSHOT</version>
     <dependencies>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
             <version>4.11</version>
         </dependency>
         <dependency>
             <groupId>mysql</groupId>
             <artifactId>mysql-connector-java</artifactId>
             <version>5.1.17</version>
         </dependency>
         <dependency>
             <groupId>org.mybatis</groupId>
             <artifactId>mybatis</artifactId>
             <version>3.2.1</version>
         </dependency>
     </dependencies>
 </project>

二.编写自定义类（area.java）

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.mybatis.domain.self;

 import java.util.ArrayList;
 import java.util.List;

 /**
  * 自关联
  */
 public class Area {
     private Integer id ;

     private String areaName ;
     //上级区域
     private Area parentArea ;

     public Area(){
     }

     public Area(String name){
         this.areaName = name;
     }

     private List<Area> children = new ArrayList<Area>();

     public Integer getId() {
         return id;
     }

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

     public String getAreaName() {
         return areaName;
     }

     public void setAreaName(String areaName) {
         this.areaName = areaName;
     }

     public Area getParentArea() {
         return parentArea;
     }

     public void setParentArea(Area parentArea) {
         this.parentArea = parentArea;
     }

     public List<Area> getChildren() {
         return children;
     }

     public void setChildren(List<Area> children) {
         this.children = children;
     }

     //定义用于绑定关系的方法
     public void addChildren(Area...areas){
         for(Area a : areas){
             this.getChildren().add(a) ;
             a.setParentArea(this);
         }
     }
 }

三.编写配置文件

1>.mybatis-config.xml 文件内容

 <?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>
         <property name="driver" value="com.mysql.jdbc.Driver"/>
         <property name="url" value="jdbc:mysql://localhost:5200/yinzhengjie"/>
         <property name="username" value="root"/>
         <property name="password" value="yinzhengjie"/>
     </properties>

     <!-- 我们使用typeAliases标签给我们自定义类起个别名。-->
     <typeAliases>
         <typeAlias type="cn.org.yinzhengjie.mybatis.domain.self.Area" alias="_Area" />
     </typeAliases>

     <environments default="development">
         <environment id="development">
             <transactionManager type="JDBC"/>
             <dataSource type="POOLED">
                 <property name="driver" value="${driver}"/>
                 <property name="url" value="${url}"/>
                 <property name="username" value="${username}"/>
                 <property name="password" value="${password}"/>
             </dataSource>
         </environment>
     </environments>
     <mappers>
         <!-- 我们使用mapper标签指定映射文件，使用resource指定具体的路径，如果没有写绝对路径，默认的根路径就在resources目录中-->
         <mapper resource="AreaMapper.xml"/>
     </mappers>
 </configuration>

2>.AreaMapper.xml 文件内容

 <?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">
 <!-- 定义名字空间 -->
 <mapper namespace="areas">
     <!-- useGeneratedKeys的值为true时，表示需要使用数据库深层的keys，同时我们需要指定使用哪个深层的key。而指定具体使用哪个key我们使用keyProperty来定义！ -->
     <insert id="insert" useGeneratedKeys="true" keyProperty="id">
         insert into areas(areaname,pid) values(#{areaName}, #{parentArea.id}) ;
     </insert>

     <select id="selectOne" resultMap="rm_Area">
         select
             s.id sid ,
             s.areaname sname ,
             p.id pid ,
             p.areaname pname,
             c.id cid ,
             c.areaname cname
         from
             areas s
             left outer join areas p on p.id = s.pid
             left outer join areas c on s.id = c.pid
         where
           s.id = #{id} ;
     </select>

     <resultMap id="rm_Area" type="_Area">
         <id column="sid" property="id" />
         <result column="sname" property="areaName" />
         <association column="pid" property="parentArea" javaType="_Area">
             <id column="pid" property="id"/>
             <result column="pname" property="areaName"/>
         </association>
         <collection property="children" ofType="_Area" column="sid">
             <id column="cid" property="id"/>
             <result column="cname" property="areaName"/>
         </collection>
     </resultMap>
 </mapper>

四.编写测试代码

1>.编写测试代码如下：

 /*
 @author :yinzhengjie
 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 EMAIL:y1053419035@qq.com
 */
 package cn.org.yinzhengjie.mybatis.test;

 import cn.org.yinzhengjie.mybatis.domain.self.Area;
 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 org.junit.Test;

 import java.io.InputStream;
 import java.util.List;

 /**
  * 测试自关联
  */
 public class TestSelf {
     @Test
     public void testInsertCustomer() throws Exception {
         InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
         SqlSessionFactory sf = new SqlSessionFactoryBuilder().build(in);
         SqlSession sess = sf.openSession();
         Area china = new Area("zhongguo") ;
         Area bj = new Area("beijing") ;
         Area hb = new Area("hebeisheng") ;
         Area haidian = new Area("haidian") ;
         Area chaoyang = new Area("chaoyang") ;
         Area shijiangzhuang = new Area("shijiangzhuang") ;
         Area handan = new Area("handan") ;
         Area guangfugucheng = new Area("guangfugucheng-1") ;
         Area wahuanggong = new Area("wahuanggong-2") ;

         //绑定关联关系
         china.addChildren(bj,hb);
         bj.addChildren(haidian,chaoyang);
         hb.addChildren(shijiangzhuang,handan);
         handan.addChildren(guangfugucheng,wahuanggong);

         //往数据库中插入数据
         sess.insert("areas.insert" , china);
         sess.insert("areas.insert" , bj);
         sess.insert("areas.insert" , hb);
         sess.insert("areas.insert" , haidian);
         sess.insert("areas.insert" , chaoyang);
         sess.insert("areas.insert" , shijiangzhuang);
         sess.insert("areas.insert" , handan);
         sess.insert("areas.insert" , guangfugucheng);
         sess.insert("areas.insert" , wahuanggong);

         //提交事物
         sess.commit();
         sess.close();

         System.out.println("数据插入成功！");
     }

     @Test
     public void testSelectOne() throws Exception {
         InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
         SqlSessionFactory sf = new SqlSessionFactoryBuilder().build(in);
         SqlSession sess = sf.openSession();
         Area obj = sess.selectOne("areas.selectOne" , 2) ;
         List<Area> children = obj.getChildren();
         for (Area child : children) {
             System.out.println(child.getAreaName());
         }
         sess.commit();
         sess.close();
     }
 }

2>.查询数据库执行结果如下：