MybatisPlus|整合SpringBoot
1. 基础知识介绍
1.1 MP概要
MyBatis-Plus（简称 MP）是一个 MyBatis 的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。
1.2 MP特性
- 无侵入：只做增强不做改变，引入它不会对现有工程产生影响，如丝般顺滑
- 损耗小：启动即会自动注入基本 CURD，性能基本无损耗，直接面向对象操作
- 强大的 CRUD 操作：内置通用 Mapper、通用 Service，仅仅通过少量配置即可实现单表大部分 CRUD 操作，更有强大的条件构造器，满足各类使用需求
- 支持 Lambda 形式调用：通过 Lambda 表达式，方便的编写各类查询条件，无需再担心字段写错
- 支持主键自动生成：支持多达 4 种主键策略（内含分布式唯一 ID 生成器 - Sequence），可自由配置，完美解决主键问题
- 支持 ActiveRecord 模式：支持 ActiveRecord 形式调用，实体类只需继承 Model 类即可进行强大的 CRUD 操作
- 支持自定义全局通用操作：支持全局通用方法注入（ Write once, use anywhere ）
- 内置代码生成器：采用代码或者 Maven 插件可快速生成 Mapper 、 Model 、 Service 、 Controller 层代码，支持模板引擎，更有超多自定义配置等您来使用
- 内置分页插件：基于 MyBatis 物理分页，开发者无需关心具体操作，配置好插件之后，写分页等同于普通 List 查询
- 分页插件支持多种数据库：支持 MySQL、MariaDB、Oracle、DB2、H2、HSQL、SQLite、Postgre、SQLServer 等多种数据库
- 内置性能分析插件：可输出 Sql 语句以及其执行时间，建议开发测试时启用该功能，能快速揪出慢查询
- 内置全局拦截插件：提供全表 delete 、 update 操作智能分析阻断，也可自定义拦截规则，预防误操作
2. 环境准备
- 操作系统：macOS Catalina 10.15.3
- IDEA：IntelliJ IDEA 2019.1 (Ultimate Edition)
- JDK：1.8
- SpringBoot：2.3.1
- MybatisPlus：3.3.2
- Mysql：8.0.19
3. 项目结构
4. 基本操作过程
4.1 创建测试表
CREATE DATABASE mp;
USE mp;
DROP TABLE IF EXISTS `tbl_employee`;
CREATE TABLE `tbl_employee` (
`id` int NOT NULL AUTO_INCREMENT,
`last_name` varchar(45) DEFAULT NULL,
`email` varchar(45) DEFAULT NULL,
`gender` char(1) DEFAULT NULL,
`age` int DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
LOCK TABLES `tbl_employee` WRITE;
INSERT INTO `tbl_employee` VALUES (1,'Tom','[email protected]','1',22),(2,'Hedon','Hedon@hedon,com','1',21),(3,'Jerry','[email protected]','2',18),(4,'White','[email protected]','2',30);
UNLOCK TABLES;
4.2 创建 SpringBoot 的 Web 项目
4.3 编写 pom.xml 文件，加入依赖坐标
重点：
- mybatis-plus
- lombok
<dependency>
<groupId>org.projectlombokgroupId>
<artifactId>lombokartifactId>
<optional>trueoptional>
dependency>
<dependency>
<groupId>com.baomidougroupId>
<artifactId>mybatis-plus-boot-starterartifactId>
<version>3.3.2version>
dependency>
4.4 编写配置文件 application.properties，配置数据库连接信息
spring.application.name=itcast-mp-springboot
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mp
spring.datasource.username=root
spring.datasource.password=root
在 Spring Boot 启动类中添加 @MapperScan 注解，扫描 Mapper 文件夹
4.6 编写实体类 Employee
package it.cast.mp.itcastmpspringboot.pojo;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
/**
* @author Hedon Wang
* @create 2020-06-24 22:53
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
@TableName(value = "tbl_employee")
public class Employee {
@TableId(value = "id",type = IdType.AUTO)
private Integer id ; // int
private String lastName;
private String email ;
private Integer gender;
private Integer age ;
private Double salary ;
}
4.7 编写Mapper接口，并继承MP提供的BaseMapper
package it.cast.mp.itcastmpspringboot.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import it.cast.mp.itcastmpspringboot.pojo.Employee;
/**
* @author Hedon Wang
* @create 2020-06-25 00:25
*/
public interface EmployeeMapper extends BaseMapper<Employee> {
}
4.8 测试 selectList()
@RunWith(SpringRunner.class)
@SpringBootTest
class ItcastMpSpringbootApplicationTests {
@Autowired
EmployeeMapper employeeMapper;
@Test
public void testSearchList(){
List<Employee> employees = employeeMapper.selectList(null);
for (Employee employee:employees){
System.out.println(employee);
}
}
}
- 测试结果
5. 项目源码
5.1 ItcastMpSpringbootApplication.java
package it.cast.mp.itcastmpspringboot;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@MapperScan("it.cast.mp.itcastmpspringboot.mapper")
@SpringBootApplication
public class ItcastMpSpringbootApplication {
public static void main(String[] args) {
SpringApplication.run(ItcastMpSpringbootApplication.class, args);
}
}
5.2 Employee.java
package it.cast.mp.itcastmpspringboot.pojo;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
/**
* @author Hedon Wang
* @create 2020-06-24 22:53
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
@TableName(value = "tbl_employee")
public class Employee {
@TableId(value = "id",type = IdType.AUTO)
private Integer id ; // int
private String lastName;
private String email ;
private Integer gender;
private Integer age ;
private Double salary ;
}
5.3 EmployeeMapper.java
package it.cast.mp.itcastmpspringboot.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import it.cast.mp.itcastmpspringboot.pojo.Employee;
/**
* @author Hedon Wang
* @create 2020-06-25 00:25
*/
public interface EmployeeMapper extends BaseMapper<Employee> {
}
5.4 application.properties
spring.application.name=itcast-mp-springboot
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mp
spring.datasource.username=root
spring.datasource.password=root
5.5 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
5.6 ItcastMpSpringbootApplicationTests.java
package it.cast.mp.itcastmpspringboot;
import it.cast.mp.itcastmpspringboot.mapper.EmployeeMapper;
import it.cast.mp.itcastmpspringboot.pojo.Employee;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.List;
@RunWith(SpringRunner.class)
@SpringBootTest
class ItcastMpSpringbootApplicationTests {
@Autowired
EmployeeMapper employeeMapper;
@Test
void contextLoads() {
}
@Test
public void testSearchList(){
List<Employee> employees = employeeMapper.selectList(null);
for (Employee employee:employees){
System.out.println(employee);
}
}
}
5.7 pom.xml
<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>4.0.0modelVersion>
<parent>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-parentartifactId>
<version>2.3.1.RELEASEversion>
<relativePath/>
parent>
<groupId>it.cast.mpgroupId>
<artifactId>itcast-mp-springbootartifactId>
<version>0.0.1-SNAPSHOTversion>
<name>itcast-mp-springbootname>
<description>Demo project for Spring Bootdescription>
<properties>
<java.version>1.8java.version>
properties>
<dependencies>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starterartifactId>
dependency>
<dependency>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-starter-testartifactId>
<scope>testscope>
dependency>
<dependency>
<groupId>org.projectlombokgroupId>
<artifactId>lombokartifactId>
<optional>trueoptional>
dependency>
<dependency>
<groupId>com.baomidougroupId>
<artifactId>mybatis-plus-boot-starterartifactId>
<version>3.3.2version>
dependency>
dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.bootgroupId>
<artifactId>spring-boot-maven-pluginartifactId>
plugin>
plugins>
build>
project>