MyBatis中的ResultMap

其他 2018-05-27 23:14:26 阅读次数: 1

MySqlSessionFactory.java

package factory;

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 java.io.InputStream;


public class MySqlSessionFactory {
   private static SqlSessionFactory sqlSessionFactory = null;

   static{
      // 初始化创建SqlSessionFactory对象
      try {
         InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
         // 读取mybatis-config.xml文件
         sqlSessionFactory = new SqlSessionFactoryBuilder()
               .build(inputStream);
      } catch (Exception e) {
         e.printStackTrace();
      }
   }

   public static SqlSession getSqlSession(){
      // 获取SqlSession对象的静态方法
      return sqlSessionFactory.openSession();
   }

   public static SqlSessionFactory getSqlSessionFactory() {
      // 获取SqlSessionFactory的静态方法
      return sqlSessionFactory;
   }


}

Clazz.java

package pojo;

import java.util.List;
/**
 * CREATE TABLE `tb_clazz` (
 id INT(11) PRIMARY KEY AUTO_INCREMENT,
 code VARCHAR(18) DEFAULT NULL
 ) COMMENT '班级表';
 INSERT INTO tb_clazz(CODE) VALUES ('j1601');
 INSERT INTO tb_clazz(CODE) VALUES ('j1602');
 */


public class Clazz {
   
   private Integer id;
   private String code;
   private List<Student> students;

   public Clazz() {
      super();
   }

   public Integer getId() {
      return id;
   }
   public void setId(Integer id) {
      this.id = id;
   }
   public String getCode() {
      return code;
   }
   public void setCode(String code) {
      this.code = code;
   }
   public List<Student> getStudents() {
      return students;
   }
   public void setStudents(List<Student> students) {
      this.students = students;
   }

   @Override
   public String toString() {
      return "Clazz [id=" + id + ", code=" + code + "]";
   }
   

}

Student.java

package pojo;
/**
 * CREATE TABLE `tb_student` (
 id INT(11) PRIMARY KEY AUTO_INCREMENT,
 NAME VARCHAR(18) DEFAULT NULL,
 sex CHAR(2) DEFAULT NULL,
 age INT(11) DEFAULT NULL,
 clazz_id INT(11),
 FOREIGN KEY (clazz_id) REFERENCES tb_clazz(id)
 ) COMMENT '学生表';
 INSERT INTO tb_student(NAME, sex, age, clazz_id) VALUES ('tom', '男', 22, 1);
 INSERT INTO tb_student(NAME, sex, age, clazz_id) VALUES ('rose', '女', 18, 1);
 INSERT INTO tb_student(NAME, sex, age, clazz_id) VALUES ('tom', '男', 25, 2);
 INSERT INTO tb_student(NAME, sex, age, clazz_id) VALUES ('mary', '女', 20, 2);
 */


public class Student {
   
   private Integer id;
   private String name;
   private String sex;
   private Integer age;
   private Clazz clazz;// 关联的Clazz对象

   public Student() {
      super();
   }

   public Integer getId() {
      return id;
   }
   public void setId(Integer id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getSex() {
      return sex;
   }
   public void setSex(String sex) {
      this.sex = sex;
   }
   public Integer getAge() {
      return age;
   }
   public void setAge(Integer age) {
      this.age = age;
   }
   public Clazz getClazz() {
      return clazz;
   }
   public void setClazz(Clazz clazz) {
      this.clazz = clazz;
   }

   @Override
   public String toString() {
      return "Student [id=" + id + ", name=" + name + ", sex=" + sex
            + ", age=" + age + ", clazz=" + clazz + "]";
   }
   

}

User.java

package pojo;

import java.io.Serializable;
/**
 * CREATE TABLE `tb_user2` (
 user_id INT(11) PRIMARY KEY AUTO_INCREMENT,
 user_name VARCHAR(18) DEFAULT NULL,
 user_sex CHAR(2) DEFAULT NULL,
 user_age INT(11) DEFAULT NULL
 ) COMMENT '用户表2';
 INSERT INTO tb_user2(user_name, user_sex, user_age) VALUES ('jack', '男', 22);
 INSERT INTO tb_user2(user_name, user_sex, user_age) VALUES ('rose', '女', 18);
 INSERT INTO tb_user2(user_name, user_sex, user_age) VALUES ('tom', '男', 25);
 INSERT INTO tb_user2(user_name, user_sex, user_age) VALUES ('mary', '女', 20);
 */


public class User implements Serializable{
   
   private Integer id;// 用户标识
   private String name;// 用户姓名
   private String sex;// 用户性别
   private Integer age;// 用户年龄
   
   public User() {
        // 无参数构造器
      super();
   }
   
   public User( String name, String sex, Integer age) {
        // 有参数构造器
      super();
      this.name = name;
      this.sex = sex;
      this.age = age;
   }

    // setter和getter方法
   public Integer getId() {
      return id;
   }
   public void setId(Integer id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getSex() {
      return sex;
   }
   public void setSex(String sex) {
      this.sex = sex;
   }
   public Integer getAge() {
      return age;
   }
   public void setAge(Integer age) {
      this.age = age;
   }

   @Override
   public String toString() {
      return "User [id=" + id + ", name=" + name + ", sex=" + sex + ", age="
            + age + "]";
   }
   

}

db.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://192.168.1.13:3306/mybatis?useSSL=false
username=root
password=Abcdef@123456

log4j.properties

log4j.rootLogger=ERROR, stdout
# 全局的日志配置
log4j.logger.UserMapper=DEBUG
# MyBatis的日志配置
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n
# 控制台输出

mybatis-config.xml

<?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">
  <!--  XML 配置文件包含对 MyBatis 系统的核心设置 -->
<configuration>
   <properties resource="db.properties"/>
   <!-- 指定 MyBatis 所用日志的具体实现 -->
   <settings>
      <setting name="logImpl" value="LOG4J"/>
   </settings>
   <environments default="mysql">
   <!-- 环境配置，即连接的数据库。 -->
    <environment id="mysql">
    <!--  指定事务管理类型，type="JDBC"指直接简单使用了JDBC的提交和回滚设置 -->
      <transactionManager type="JDBC"/>
      <!--  dataSource指数据源配置，POOLED是JDBC连接对象的数据源连接池的实现。 -->
      <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告诉了MyBatis去哪里找持久化类的映射文件 -->
  <mappers>
   <mapper resource="UserMapper.xml"/>
  </mappers>
</configuration>

UserMapper.xml

<?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">

<!-- namespace指用户自定义的命名空间。 -->
<mapper namespace="UserMapper">

  <!-- select操作 
  resultType="map"表示返回的是一个Map对象
  使用列名做key，值做value -->
  <select id="selectUser" resultType="map">
   SELECT * FROM tb_user
  </select>
 
  <resultMap id="userResultMap" type="pojo.User">
     <id property="id" column="user_id" />
     <result property="name" column="user_name"/>
     <result property="sex" column="user_sex"/>
     <result property="age" column="user_age"/>
  </resultMap>
    <!--resultMap="userResultMap"表示引用上面的resultMap进行数据库表和返回类型对象的映射-->
    <select id="selectUser2" resultMap="userResultMap">
     SELECT * FROM tb_user2
   </select>
  
  
  <!-- 映射学生对象的resultMap -->
  <resultMap id="studentResultMap" type="pojo.Student">
     <id property="id" column="id" />
     <result property="name" column="name"/>
     <result property="sex" column="sex"/>
     <result property="age" column="age"/>
     <!-- 关联映射 -->
     <association property="clazz" column="clazz_id" 
     javaType="pojo.Clazz"
     select="selectClazzWithId"/>
  </resultMap>

    <!-- 根据班级id查询班级 -->
    <select id="selectClazzWithId" resultType="pojo.Clazz">
     SELECT * FROM tb_clazz where id = #{id}
    </select>

    <!-- 查询所有学生信息 -->
    <select id="selectStudent" resultMap="studentResultMap">
     SELECT * FROM tb_student
    </select>
  
  <!-- 映射班级对象的resultMap -->
  <resultMap id="clazzResultMap" type="pojo.Clazz">
     <id property="id" column="id" />
     <result property="code" column="code"/>
     <!-- 班级的学生属性，因为一个班级有多个学生，所以该属性是一个集合 -->
     <collection property="students" javaType="ArrayList"
     column="id" ofType="pojo.Student"
     select="selectStudentWithId"/>
  </resultMap>

    <!-- 根据班级id查询学生 -->
   <select id="selectStudentWithId" resultType="pojo.Student">
      SELECT * FROM tb_student where clazz_id = #{id}
   </select>
   
   <!-- 查询所有班级信息 -->
    <select id="selectClazz" resultMap="clazzResultMap">
     SELECT * FROM tb_clazz
    </select>
  
</mapper>

ResultMapTest.java

import factory.MySqlSessionFactory;
import org.apache.ibatis.session.SqlSession;
import pojo.User;
import java.util.List;


public class ResultMapTest {

   public static void main(String[] args) {
      SqlSession session = MySqlSessionFactory.getSqlSession();
      // 获得Session实例
      List<User> user_list
         = session.selectList("UserMapper.selectUser2");
            // 查询tb_user2表所有数据返回List集合,集合中的每个元素都是一个Map
      for(User user : user_list){
         System.out.println(user);
            // 遍历List集合，打印每一个Map对象
      }
      session.commit();
        // 提交事务
      session.close();
        // 关闭Session
   }


}

SelectClazzTest.java

import factory.MySqlSessionFactory;
import org.apache.ibatis.session.SqlSession;
import pojo.Clazz;
import pojo.Student;
import java.util.List;


public class SelectClazzTest {

   public static void main(String[] args) throws Exception {
      SqlSession session = MySqlSessionFactory.getSqlSession();
        // 获得Session实例
      List<Clazz> clazz_list
         = session.selectList("UserMapper.selectClazz");
            // 查询tb_clazz表所有数据返回List集合,集合中的每个元素都是一个Clazz对象
      for(Clazz clazz : clazz_list){
         System.out.println(clazz);
         List<Student> student_list = clazz.getStudents();
         for(Student stu : student_list){
            System.out.println(stu.getId() + " " + stu.getName() + " " + stu.getSex() + " " + stu.getAge());
                // 遍历List集合，打印每一个Clazz对象和该Clazz关联的所有Student对象
         }
      }
      session.commit();
        // 提交事务
      session.close();
        // 关闭Session
   }


}

SelectMapTest.java

import factory.MySqlSessionFactory;
import org.apache.ibatis.session.SqlSession;
import java.util.List;
import java.util.Map;


public class SelectMapTest {

   public static void main(String[] args) throws Exception {
      SqlSession session = MySqlSessionFactory.getSqlSession();
        // 获得Session实例
      List<Map<String,Object>> list 
         = session.selectList("UserMapper.selectUser");
            // 查询tb_user表所有数据返回List集合,集合中的每个元素都是一个Map
      for(Map<String,Object> row : list){
         System.out.println(row);
            // 遍历List集合，打印每一个Map对象
      }
      session.commit();
        // 提交事务
      session.close();
        // 关闭Session
   }


}

SelectStudentTest.java

import factory.MySqlSessionFactory;
import org.apache.ibatis.session.SqlSession;
import pojo.Student;
import java.util.List;


public class SelectStudentTest {

   public static void main(String[] args) throws Exception {
      SqlSession session = MySqlSessionFactory.getSqlSession();
        // 获得Session实例
      List<Student> student_list
         = session.selectList("UserMapper.selectStudent");
            // 查询tb_student表所有数据返回List集合,集合中的每个元素都是一个Student对象
      for(Student stu : student_list){
         System.out.println(stu);
            // 遍历List集合，打印每一个Student对象，该对象包含关联的Clazz对象
      }
      session.commit();
        // 提交事务
      session.close();
        // 关闭Session
   }


}

pom.xml

<?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>shanghai</groupId>
    <artifactId>ResultMaps</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.testng</groupId>
            <artifactId>testng</artifactId>
            <version>6.11</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.1</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.45</version>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.20.1</version>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.soureEncodng>UTF-8</maven.compiler.soureEncodng>
    </properties>
    
</project>

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