Mybatis-Plus：快速开始（SpringBoot + Mybatis + Mybatis）

Posted 2022-03-14 CodeJiao

01:Mybatis-Plus：了解Mybatis-Plus、快速开始（Mybatis + Mybatis-Plus，Mybatis-Plus自动做了属性映射）

02：Mybatis-Plus：快速开始（Spring + Mybatis + Mabatis-Plus）

03：Mybatis-Plus：快速开始（SpringBoot + Mybatis + Mybatis）

1. 快速开始（SpringBoot + Mybatis + Mybatis）

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1.1 创建工程

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1.2 导入依赖

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.tian</groupId>
    <artifactId>springboot-mybatis_plus</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-mybatis_plus</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!--简化代码的工具包-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <!--mybatis-plus的springboot支持-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.3.2</version>
        </dependency>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.25</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

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1.3 配置日志信息

log4j.properties

log4j.rootLogger=DEBUG,A1

log4j.appender.A1=org.apache.log4j.ConsoleAppender
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=[%t] [%c]-[%p] %m%n

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1.4 创建数据

Navicat执行下列SQL语句

CREATE DATABASE mp;
USE mp;

-- 创建测试表
CREATE TABLE `tb_user` (
	`id` BIGINT ( 20 ) NOT NULL AUTO_INCREMENT COMMENT '主键ID',
	`user_name` VARCHAR ( 20 ) NOT NULL COMMENT '用户名',
	`password` VARCHAR ( 20 ) NOT NULL COMMENT '密码',
	`name` VARCHAR ( 30 ) DEFAULT NULL COMMENT '姓名',
	`age` INT ( 11 ) DEFAULT NULL COMMENT '年龄',
	`email` VARCHAR ( 50 ) DEFAULT NULL COMMENT '邮箱',
	PRIMARY KEY ( `id` ) 
) ENGINE = INNODB AUTO_INCREMENT = 1 DEFAULT CHARSET = utf8;

-- 插入测试数据
INSERT INTO `tb_user` ( `id`, `user_name`, `password`, `name`, `age`, `email` )
VALUES
	( '1', 'zhangsan', '123456', '张三', '18', '[e-mail]' );
INSERT INTO `tb_user` ( `id`, `user_name`, `password`, `name`, `age`, `email` )
VALUES
	( '2', 'lisi', '123456', '李四', '20', '[e-mail]' );
INSERT INTO `tb_user` ( `id`, `user_name`, `password`, `name`, `age`, `email` )
VALUES
	( '3', 'wangwu', '123456', '王五', '28', '[e-mail]' );
INSERT INTO `tb_user` ( `id`, `user_name`, `password`, `name`, `age`, `email` )
VALUES
	( '4', 'zhaoliu', '123456', '赵六', '21', '[e-mail]' );
INSERT INTO `tb_user` ( `id`, `user_name`, `password`, `name`, `age`, `email` )
VALUES
	( '5', 'sunqi', '123456', '孙七', '24', '[e-mail]' );

执行结果：

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1.5 编写application.properties（主要是数据库的配置信息）

application.properties

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/mp?useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true&useSSL=false
spring.datasource.username=root
spring.datasource.password=317525

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1.6 编写pojo

package pojo;

import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data  // get / set方法
@NoArgsConstructor // 无参构造函数
@AllArgsConstructor // 有参构造函数
@TableName("tb_user")
public class User 
    private Long id;
    private String userName;
    private String password;
    private String name;
    private Integer age;
    private String email;

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1.7 编写mapper

UserMapper.java

package mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import pojo.User;

public interface UserMapper extends BaseMapper<User> 
    User findById(Long id);

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1.8 配置启动类

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1.9 编写测试用例

SpringbootMybatisPlusApplicationTests

package com.tian.springbootmybatis_plus;

import mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import pojo.User;

import java.util.List;

@SpringBootTest
class SpringbootMybatisPlusApplicationTests 

    @Autowired
    private UserMapper userMapper;

    @Test
    public void testSelectList() 
        // 现在我们使用MP给我们提供的方法 null就表示没有查询条件 查询所有的数据出来
        List<User> users = this.userMapper.selectList(null);
        for (User user : users) 
            System.out.println(user);
        
    

运行结果：

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