七、面向接口的方式进行CRUD_设计模式面向接口crud-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_45372862/article/details/129247569

新建一个maven模块

mybatis-005-crud2

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>com.powernode</groupId>
    <artifactId>mybatis-005-crud2</artifactId>
    <version>1.0-SNAPSHOT</version>
    <!--打包方式-->
    <packaging>jar</packaging>

    <dependencies>
        <!--mybatis依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.10</version>
        </dependency>
        <!--mysql驱动依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.30</version>
        </dependency>
        <!--junit依赖-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>
        <!--logback依赖g-->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.11</version>
        </dependency>
    </dependencies>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
    </properties>

</project>

在resources目录下新建、编辑jdbc.properties文件

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/powernode
jdbc.username=root
jdbc.password=root

在resources目录下新建、编辑mybatis-config.xml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="jdbc.properties" />
    <environments default="powernodeDB">
        <environment id="powernodeDB">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="CarMapper.xml"/>
    </mappers>
</configuration>

在resources目录下新建、编写CarMapper.xml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="com.powernode.mybatis.mapper.CarMapper">

    <insert id="insert">
        insert into t_car values(null, #{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})
    </insert>
    <delete id="deleteById">
        delete from t_car where id = #{id}
    </delete>
    <update id="update">
        update t_car set
        car_num=#{carNum},brand=#{brand},guide_price=#{guidePrice},produce_time=#{produceTime},car_type=#{carType}
        where id = #{id}
    </update>
    <select id="selectById" resultType="com.powernode.mybatis.pojo.Car">
        select
            id,
            car_num as carNum,
            brand,
            guide_price as guidePrice,
            produce_time as produceTime,
            car_type as carType
        from t_car where id = #{id}
    </select>
    <select id="selectAll" resultType="com.powernode.mybatis.pojo.Car">
        select
            id,
            car_num as carNum,
            brand,
            guide_price as guidePrice,
            produce_time as produceTime,
            car_type as carType
        from t_car
    </select>
</mapper>

在resources目录下新建、编写logback.xml配置文件

<?xml version="1.0" encoding="UTF-8"?>

<configuration debug="false">
    <!-- 控制台输出 -->
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <!--格式化输出：%d表示日期，%thread表示线程名，%-5level：级别从左显示5个字符宽度%msg：日志消息，%n是换行符-->
            <pattern>[%thread] %-5level %logger{50} - %msg%n</pattern>
        </encoder>
    </appender>

    <!--mybatis log configure-->
    <logger name="com.apache.ibatis" level="TRACE"/>
    <logger name="java.sql.Connection" level="DEBUG"/>
    <logger name="java.sql.Statement" level="DEBUG"/>
    <logger name="java.sql.PreparedStatement" level="DEBUG"/>

    <!-- 日志输出级别,logback日志级别包括五个：TRACE < DEBUG < INFO < WARN < ERROR -->
    <root level="DEBUG">
        <appender-ref ref="STDOUT"/>
        <appender-ref ref="FILE"/>
    </root>

</configuration>

新建工具类，SqlSessionUtil

package com.powernode.mybatis.utils;

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.IOException;

/**
 * MyBatis工具类
 */
public class SqlSessionUtil {

    private SqlSessionUtil(){}

    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    // 全局的，服务器级别的，一个服务器当中定义一个即可。
    private static ThreadLocal<SqlSession> local = new ThreadLocal<>();

    /**
     * 获取会话对象。
     * @return 会话对象
     */
    public static SqlSession openSession(){
        SqlSession sqlSession = local.get();
        if (sqlSession == null) {
            sqlSession = sqlSessionFactory.openSession();
            // 将sqlSession对象绑定到当前线程上。
            local.set(sqlSession);
        }
        return sqlSession;
    }

    /**
     * 关闭SqlSession对象(从当前线程中移除SqlSession对象。)
     * @param sqlSession
     */
    public static void close(SqlSession sqlSession){
        if (sqlSession != null) {
            sqlSession.close();
            // 移除SqlSession对象和当前线程的绑定关系。
            local.remove();
        }
    }
}

新建pojo类

package com.powernode.pojo;

/**
 * 账户类，封装账户数据
 */
public class Account {
    private Long id;
    private String actno;
    private Double balance;
......
//此处省略构造方法、getting setting toString方法

编写CarMapper接口

package com.powernode.mybatis.mapper; 

import com.powernode.mybatis.pojo.Car;

import java.util.List;

// 一般使用mybatis的话，一般不叫做XXXDao了。一般都是XXXMapper。
public interface CarMapper {

    /**
     * 新增Car
     * @param car
     * @return
     */
    int insert(Car car);

    /**
     * 根据id删除Car
     * @param id
     * @return
     */
    int deleteById(Long id);

    /**
     * 修改汽车信息
     * @param car
     * @return
     */
    int update(Car car);

    /**
     * 根据id查询汽车信息
     * @param id
     * @return
     */
    Car selectById(Long id);

    /**
     * 获取所有的汽车信息。
     * @return
     */
    List<Car> selectAll();
}

编写junit测试用例

package com.powernode.mybatis.test;

import com.powernode.mybatis.mapper.CarMapper;
import com.powernode.mybatis.pojo.Car;
import com.powernode.mybatis.utils.SqlSessionUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class CarMapperTest {
    @Test
    public void testInsert(){
        SqlSession sqlSession = SqlSessionUtil.openSession();
        // 面向接口获取接口的代理对象
        CarMapper mapper = sqlSession.getMapper(CarMapper.class);
        Car car = new Car(null, "4444", "奔驰C200", 32.0, "2000-10-10", "新能源");
        int count = mapper.insert(car);
        System.out.println(count);
        sqlSession.commit();
    }
    @Test
    public void testDeleteById(){
        SqlSession sqlSession = SqlSessionUtil.openSession();
        CarMapper mapper = sqlSession.getMapper(CarMapper.class);
        int count = mapper.deleteById(20L);
        System.out.println(count);
        sqlSession.commit();
    }
    @Test
    public void testUpdate(){
        SqlSession sqlSession = SqlSessionUtil.openSession();
        CarMapper mapper = sqlSession.getMapper(CarMapper.class);
        Car car = new Car(25L, "2222", "凯美瑞222", 3.0, "2000-10-10", "新能源");
        mapper.update(car);
        sqlSession.commit();
    }
    @Test
    public void testSelectById(){
        SqlSession sqlSession = SqlSessionUtil.openSession();
        CarMapper mapper = sqlSession.getMapper(CarMapper.class);
        Car car = mapper.selectById(25L);
        System.out.println(car);
    }
    @Test
    public void testSelectAll(){
        SqlSession sqlSession = SqlSessionUtil.openSession();
        CarMapper mapper = sqlSession.getMapper(CarMapper.class);
        List<Car> cars = mapper.selectAll();
        cars.forEach(car -> System.out.println(car));
    }
}