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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

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

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0"
 3          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5     <modelVersion>4.0.0</modelVersion>
 6     <groupId>cn.org.yinzhengjie</groupId>
 7     <artifactId>Mybatis</artifactId>
 8     <version>1.0-SNAPSHOT</version>
 9     <dependencies>
10         <dependency>
11             <groupId>junit</groupId>
12             <artifactId>junit</artifactId>
13             <version>4.11</version>
14         </dependency>
15         <dependency>
16             <groupId>mysql</groupId>
17             <artifactId>mysql-connector-java</artifactId>
18             <version>5.1.17</version>
19         </dependency>
20         <dependency>
21             <groupId>org.mybatis</groupId>
22             <artifactId>mybatis</artifactId>
23             <version>3.2.1</version>
24         </dependency>
25     </dependencies>
26 </project>

二.编写自定义类（area.java）

 1 /*
 2 @author :yinzhengjie
 3 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 4 EMAIL:y1053419035@qq.com
 5 */
 6 package cn.org.yinzhengjie.mybatis.domain.self;
 7 
 8 import java.util.ArrayList;
 9 import java.util.List;
10 
11 
12 /**
13  * 自关联
14  */
15 public class Area {
16     private Integer id ;
17 
18     private String areaName ;
19     //上级区域
20     private Area parentArea ;
21 
22     public Area(){
23     }
24 
25     public Area(String name){
26         this.areaName = name;
27     }
28 
29     private List<Area> children = new ArrayList<Area>();
30 
31     public Integer getId() {
32         return id;
33     }
34 
35     public void setId(Integer id) {
36         this.id = id;
37     }
38 
39     public String getAreaName() {
40         return areaName;
41     }
42 
43     public void setAreaName(String areaName) {
44         this.areaName = areaName;
45     }
46 
47     public Area getParentArea() {
48         return parentArea;
49     }
50 
51     public void setParentArea(Area parentArea) {
52         this.parentArea = parentArea;
53     }
54 
55     public List<Area> getChildren() {
56         return children;
57     }
58 
59     public void setChildren(List<Area> children) {
60         this.children = children;
61     }
62 
63     //定义用于绑定关系的方法
64     public void addChildren(Area...areas){
65         for(Area a : areas){
66             this.getChildren().add(a) ;
67             a.setParentArea(this);
68         }
69     }
70 }

三.编写配置文件

1>.mybatis-config.xml 文件内容

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 <configuration>
 6     <properties>
 7         <property name="driver" value="com.mysql.jdbc.Driver"/>
 8         <property name="url" value="jdbc:mysql://localhost:5200/yinzhengjie"/>
 9         <property name="username" value="root"/>
10         <property name="password" value="yinzhengjie"/>
11     </properties>
12 
13     <!-- 我们使用typeAliases标签给我们自定义类起个别名。-->
14     <typeAliases>
15         <typeAlias type="cn.org.yinzhengjie.mybatis.domain.self.Area" alias="_Area" />
16     </typeAliases>
17 
18     <environments default="development">
19         <environment id="development">
20             <transactionManager type="JDBC"/>
21             <dataSource type="POOLED">
22                 <property name="driver" value="${driver}"/>
23                 <property name="url" value="${url}"/>
24                 <property name="username" value="${username}"/>
25                 <property name="password" value="${password}"/>
26             </dataSource>
27         </environment>
28     </environments>
29     <mappers>
30         <!-- 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-->
31         <mapper resource="AreaMapper.xml"/>
32     </mappers>
33 </configuration>

2>.AreaMapper.xml 文件内容

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 3         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 4 <!-- 定义名字空间 -->
 5 <mapper namespace="areas">
 6     <!-- 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！ -->
 7     <insert id="insert" useGeneratedKeys="true" keyProperty="id">
 8         insert into areas(areaname,pid) values(#{areaName}, #{parentArea.id}) ;
 9     </insert>
10 
11     <select id="selectOne" resultMap="rm_Area">
12         select
13             s.id sid ,
14             s.areaname sname ,
15             p.id pid ,
16             p.areaname pname,
17             c.id cid ,
18             c.areaname cname
19         from
20             areas s
21             left outer join areas p on p.id = s.pid
22             left outer join areas c on s.id = c.pid
23         where
24           s.id = #{id} ;
25     </select>
26     
27     <resultMap id="rm_Area" type="_Area">
28         <id column="sid" property="id" />
29         <result column="sname" property="areaName" />
30         <association column="pid" property="parentArea" javaType="_Area">
31             <id column="pid" property="id"/>
32             <result column="pname" property="areaName"/>
33         </association>
34         <collection property="children" ofType="_Area" column="sid">
35             <id column="cid" property="id"/>
36             <result column="cname" property="areaName"/>
37         </collection>
38     </resultMap>
39 </mapper>

四.编写测试代码

1>.编写测试代码如下：

 1 /*
 2 @author :yinzhengjie
 3 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 4 EMAIL:y1053419035@qq.com
 5 */
 6 package cn.org.yinzhengjie.mybatis.test;
 7 
 8 import cn.org.yinzhengjie.mybatis.domain.self.Area;
 9 import org.apache.ibatis.io.Resources;
10 import org.apache.ibatis.session.SqlSession;
11 import org.apache.ibatis.session.SqlSessionFactory;
12 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
13 import org.junit.Test;
14 
15 import java.io.InputStream;
16 import java.util.List;
17 
18 /**
19  * 测试自关联
20  */
21 public class TestSelf {
22     @Test
23     public void testInsertCustomer() throws Exception {
24         InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
25         SqlSessionFactory sf = new SqlSessionFactoryBuilder().build(in);
26         SqlSession sess = sf.openSession();
27         Area china = new Area("zhongguo") ;
28         Area bj = new Area("beijing") ;
29         Area hb = new Area("hebeisheng") ;
30         Area haidian = new Area("haidian") ;
31         Area chaoyang = new Area("chaoyang") ;
32         Area shijiangzhuang = new Area("shijiangzhuang") ;
33         Area handan = new Area("handan") ;
34         Area guangfugucheng = new Area("guangfugucheng-1") ;
35         Area wahuanggong = new Area("wahuanggong-2") ;
36 
37         //绑定关联关系
38         china.addChildren(bj,hb);
39         bj.addChildren(haidian,chaoyang);
40         hb.addChildren(shijiangzhuang,handan);
41         handan.addChildren(guangfugucheng,wahuanggong);
42 
43 
44         //往数据库中插入数据
45         sess.insert("areas.insert" , china);
46         sess.insert("areas.insert" , bj);
47         sess.insert("areas.insert" , hb);
48         sess.insert("areas.insert" , haidian);
49         sess.insert("areas.insert" , chaoyang);
50         sess.insert("areas.insert" , shijiangzhuang);
51         sess.insert("areas.insert" , handan);
52         sess.insert("areas.insert" , guangfugucheng);
53         sess.insert("areas.insert" , wahuanggong);
54 
55         //提交事物
56         sess.commit();
57         sess.close();
58 
59         System.out.println("数据插入成功！");
60     }
61 
62     @Test
63     public void testSelectOne() throws Exception {
64         InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
65         SqlSessionFactory sf = new SqlSessionFactoryBuilder().build(in);
66         SqlSession sess = sf.openSession();
67         Area obj = sess.selectOne("areas.selectOne" , 2) ;
68         List<Area> children = obj.getChildren();
69         for (Area child : children) {
70             System.out.println(child.getAreaName());
71         }
72         sess.commit();
73         sess.close();
74     }
75 }

2>.查询数据库执行结果如下：

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原文地址：https://www.cnblogs.com/yinzhengjie/p/9287310.html