Java基础-SSM之mybatis一对一外键关联

　　　　　　　　　　　　　　Java基础-SSM之mybatis一对一外键关联

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　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husbandsfk和wifesfk表

 use yinzhengjie;

 create table husbandsfk(id int primary key auto_increment , hname varchar(20)) ;

 create table wifesfk(id int primary key  auto_increment , wname varchar(20) , hid int , CONSTRAINT fk_hid FOREIGN KEY (hid) references husbandsfk(id)) ;

 alter table wifesfk add constraint unq_hid unique (hid) ;

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>

3>.目录结构如下：

二.编写自定义类

 /*
 @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.one2one.fk;

 public class Husband {
     private Integer id ;
     private String hname ;
     private Wife wife;

     public Integer getId() {
         return id;
     }

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

     public String getHname() {
         return hname;
     }

     public void setHname(String hname) {
         this.hname = hname;
     }

     public Wife getWife() {
         return wife;
     }

     public void setWife(Wife wife) {
         this.wife = wife;
     }
 }

Husband.java 文件内容

 /*
 @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.one2one.fk;

 public class Wife {
     private Integer id ;
     private String wname ;
     private Husband husband ;

     public Integer getId() {
         return id;
     }

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

     public String getWname() {
         return wname;
     }

     public void setWname(String wname) {
         this.wname = wname;
     }

     public Husband getHusband() {
         return husband;
     }

     public void setHusband(Husband husband) {
         this.husband = husband;
     }
 }

Wife.java 文件内容

三.编写配置文件

 <?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"/>
         <!--注意 : “?characterEncoding=utf-8&amp;autoReconnect=true&amp;failOverReadOnly=false&amp;allowMultiQueries=true” 表示开启批处理模式-->
         <property name="url" value="jdbc:mysql://localhost:5200/yinzhengjie?characterEncoding=utf-8&amp;autoReconnect=true&amp;failOverReadOnly=false&amp;allowMultiQueries=true"/>
         <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.one2one.fk.Husband"     alias="_HusbandFK" />
         <typeAlias type="cn.org.yinzhengjie.mybatis.domain.one2one.fk.Wife"        alias="_WifeFK" />
     </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="HusbandFKMapper.xml"/>
         <mapper resource="WifeFKMapper.xml"/>
     </mappers>
 </configuration>

mybatis-config.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="husbandsfk">
     <insert id="insert" useGeneratedKeys="true" keyProperty="id">
         insert into husbandsfk(hname) values(#{hname}) ;
     </insert>

     <select id="selectOne" resultMap="rm_Husband">
         select
           h.id hid,
           h.hname hhname ,
           w.id wid ,
           w.wname wwname ,
           w.hid whid
         from
           husbandsfk h left outer join wifesfk w on w.hid = h.id
         where
           h.id = #{id}
     </select>

     <resultMap id="rm_Husband" type="_HusbandFK">
         <id column="hid" property="id"/>
         <result column="hhname" property="hname" />
         <association property="wife" javaType="_WifeFK" column="whid">
             <id column="wid" property="id"/>
             <result column="wwname" property="wname"/>
             <association property="husband" javaType="_HusbandFk" column="whid">
                 <id column="hid" property="id"/>
                 <result column="hhname" property="hname"/>
             </association>
         </association>
     </resultMap>
 </mapper>

HusbandFKMapper.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="wifesfk">
     <insert id="insert" useGeneratedKeys="true" keyProperty="id">
         insert into wifesfk(wname , hid) values(#{wname} , #{husband.id}) ;
     </insert>

 </mapper>

WifeFKMapper.xml 文件内容

四.编写测试代码

 /*
 @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.one2one.fk.Husband;
 import cn.org.yinzhengjie.mybatis.domain.one2one.fk.Wife;
 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;

 /**
  * 测试一对一
  */
 public class TestOne2OneFK {
     /**
      * 测试插入
      */
     @Test
     public void testInsert() throws Exception {
         InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
         SqlSessionFactory sf = new SqlSessionFactoryBuilder().build(in);
         SqlSession sess = sf.openSession();
         Husband h1 = new Husband();
         h1.setHname("liyapeng");
         Wife w1 = new Wife();
         w1.setWname("wangfei");
         h1.setWife(w1);
         w1.setHusband(h1);

         sess.insert("husbandsfk.insert" , h1) ;
         sess.insert("wifesfk.insert" , w1) ;

         sess.commit();
         sess.close();
         System.out.println("插入成功！");
     }

     /**
      * 测试查询
      */
     @Test
     public void testSelectOne() throws Exception {
         InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
         SqlSessionFactory sf = new SqlSessionFactoryBuilder().build(in);
         SqlSession sess = sf.openSession();
         Husband husband = (Husband) sess.selectOne("husbandsfk.selectOne", 1);
         System.out.println(husband.getHname());
         sess.commit();
         sess.close();
     }
 }

　　运行以上代码查看数据库内容如下：