mybatisplus整合mybatis

二、使用mybatis-plus整合mybatis，完成如下要求

1、对数据库表的增加

2、对数据库表按给定id删除

3、对数据库表的全部显示

在pom.xml里引入苞米豆的mybatis-plus依赖，引入spring-core,lombok,log4j,junit等需要用到的依赖，在末尾resource声明要编译的配置文件类型和路径.properties和.xml都要编译

<?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">
    <parent>
        <artifactId>mybatis_plus</artifactId>
        <groupId>com.xzit</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>day4_mybatis_1</artifactId>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus</artifactId>
            <version>3.5.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>5.3.15</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.22</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>2.0.0-alpha7</version>
        </dependency>
        <!--<dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.9</version>
        </dependency>-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>
</project>

先来一个db.properties配置文件存数据库配置信息

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=GMT%2B8
jdbc.username=root
jdbc.password=zengyu1234

再来个SqlMapConfig.xml，引用db.properties里的信息，在末尾声明mapper的包的位置

<?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">
            <transactionManager type="JDBC"></transactionManager>
            <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>
        <package name="com.xzit.mapper"/>
    </mappers>
</configuration>

从网上拷了一个log4j.properties配置文件用来在控制台打印日志，不然mybatis-plus不打印日志

参考文章：https://blog.csdn.net/qq_15092079/article/details/105269634

### ??###
log4j.rootLogger = debug,stdout

### ???????? ###
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n

新建一个Teacher实体类

package com.xzit.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Teacher {
    private Integer id;
    private String name;
    private String addr;
    private Integer age;
    private String job;
    private Integer sal;
}

重点来了，TeacherMapper接口类要extends继承BaseMapper类，并且在泛型那里填上你要做增删改查的实体类<Teacher>，这样的话你接口里不用写方法，基本的增删改查方法在BaseMapper里已经用反射机制写好了

package com.xzit.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.xzit.entity.Teacher;

import java.util.List;

public interface TeacherMapper extends BaseMapper<Teacher> {
//    List<Teacher> selectList();
}

此时TeacherMapper.xml可以是空的啥也不写

<?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.xzit.mapper.TeacherMapper">
</mapper>

最后用junit的机制在test包里新建一个测试类进行测试，测试方法上使用@Test注解

运行结果：

增加功能：

删除功能

 

查询全部功能