MyBatis框架学习Ⅵ

resultType使用

返回单一类型

工程结构

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 resource="db.properties">
    </properties>

    <environments default="development">
        <environment id="development">
            <!-- 配置JDBC事务控制，由mybatis进行管理 -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- 配置数据源，采用mybatis连接池 -->
            <dataSource type="POOLED">
                <property name="driver" value="${db.driver}"/>
                <property name="url" value="${db.url}"/>
                <property name="username" value="${db.username}"/>
                <property name="password" value="${db.password}"/>
            </dataSource>
        </environment>
    </environments>
    <!-- 加载映射文件 -->
    <mappers>
        <package name="dao.mapper"></package>
    </mappers>
</configuration>

db.driver = com.mysql.jdbc.Driver
db.url = jdbc:mysql://localhost:3306/ee19_batis_day03?useUnicode=true&characterEncoding=utf-8
db.username = root
db.password = 123

实体类

package entity;

import java.util.Date;

public class User {
    private int id;
    private String username;
    private Date birthday;
    private String address;
    private String sex;

    public int getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", birthday=" + birthday +
                ", address='" + address + '\'' +
                ", sex='" + sex + '\'' +
                '}';
    }
}

package entity;

public class UserQueryVo {
    private User user;

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }
}

Mapper文件

<?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="dao.mapper.UserMapper">
    <select id="findUserCount" parameterType="entity.UserQueryVo" resultType="int">
        SELECT count(*) FROM user WHERE username
        LIKE '%${user.username}%'
        AND sex = #{user.sex}
    </select>
</mapper>

package dao.mapper;

import entity.User;
import entity.UserQueryVo;

import java.util.HashMap;
import java.util.List;

public interface UserMapper {
    int findUserCount(UserQueryVo vo) throws Exception;
}

测试文件

@Test
    public void testFindUserList() throws Exception {
        //读取配置文件
        //全局配置文件的路径
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);

        //创建SqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //创建SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        UserQueryVo userQueryVo = new UserQueryVo();
        User user = new User();
        user.setUsername("chaoge111");
        user.setSex("1");
        userQueryVo.setUser(user);
        List<User> userList = mapper.findUserList(userQueryVo);
        int userCount = mapper.findUserCount(userQueryVo);
        System.out.println("userList = " + userList);
        System.out.println("userCount = " + userCount);
        sqlSession.close();
    }

返回Map类型

工程结构

同上

配置文件

同上

实体类

同上

Mapper文件

<?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="dao.mapper.UserMapper">

    <resultMap id="UserRstMap" type="entity.User">
        <id column="id_" property="id"></id>
        <result column="username_" property="username"></result>
    </resultMap>

    <select id="findUserRstMap" parameterType="int" resultMap="UserRstMap">
        SELECT id id_, username username_ FROM user WHERE id = #{id}
    </select>
    
</mapper>

package dao.mapper;

import entity.User;
import entity.UserQueryVo;

import java.util.HashMap;
import java.util.List;

public interface UserMapper {
    /*
     * @param id 用户id
     * @return 返回User，这个User是映射xml文件中resultMap的type属性
     */
    User findUserRstMap(int id) throws Exception;
}

测试文件

	@Test
    public void testResultMap() throws Exception {
        //读取配置文件
        //全局配置文件的路径
        String resource = "SqlMapConfig.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);

        //创建SqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //创建SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        User userRstMap = mapper.findUserRstMap(30);

        System.out.println("userRstMap = " + userRstMap);
        sqlSession.close();
    }