MyBatisPlus:入门案例
创建数据库以及表
创建表
CREATE DATABASE `mybatis_plus` /*!40100 DEFAULT CHARACTER SET utf8mb4 */;
use `mybatis_plus`;
CREATE TABLE `user` (
`id` bigint(20) NOT NULL COMMENT '主键ID',
`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 DEFAULT CHARSET=utf8;
添加数据
INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');
创建一个maven工程
pom.xml 导入依赖
<packaging>jar</packaging>
<properties>
<spring.version>5.3.1</spring.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- 连接池 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.2.8</version>
</dependency>
<!-- junit测试 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<!-- MySQL驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.27</version>
</dependency>
<!-- 日志 -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.30</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.3</version>
</dependency>
<!-- lombok用来简化实体类 -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.16.16</version>
</dependency>
<!--MyBatis-Plus的核心依赖-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus</artifactId>
<version>3.4.3.4</version>
</dependency>
</dependencies>Spring整合MyBatis，需要MyBatis以及Spring整合MyBatis的依赖：即引入mybatis和mybatis-spring的jar包
但是，在以上的依赖列表中，并没有MyBatis以及Spring整合MyBatis的依赖，因为当我们引入了MyBatis-Plus的依赖时，就可以间接的引入这些依赖
Spring整合MyBatis
1.创建实体类
User.java
package com.tinstu.pojo;
public class User {
private Long id;
private String name;
private int age;
private String email;
public User(Long id, String name, int age, String email) {
this.id = id;
this.name = name;
this.age = age;
this.email = email;
}
public User() {
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", email='" + email + '\'' +
'}';
}
}
2.创建mybatis的核心配置文件
<?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>
</configuration>3.创建mapper文件和映射文件
package com.tinstu.mapper;
import com.tinstu.pojo.User;
import java.util.List;
public interface UserMapper {
//查询所有用户的信息
List<User> getAll();
}
映射文件
<?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.tinstu.mapper.UserMapper">
<sql id="Base">id,name,age,email</sql>
<!--List<User> getAll();-->
<select id="getAll" resultType="User">
select
<include refid="Base"></include>
from user
</select>
</mapper>4.创建db.properties
jdbc.jdbcUrl=jdbc:mysql://localhost:3306/mybatis_plus?characterEncoding=UTF-8&useUnicode=true&useSSL=false&serverTimezone = GMT
jdbc.dirverClass=com.mysql.cj.jdbc.Driver
jdbc.user=root
jdbc.password=root5.创建spring的配置文件 applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd">
<!-- 引入jdbc.properties -->
<context:property-placeholder location="classpath:dbconfig.properties"></context:property-placeholder>
<!-- 配置Druid数据源 -->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
<property name="driverClassName" value="${jdbc.dirverClass}"></property>
<property name="url" value="${jdbc.jdbcUrl}"></property>
<property name="username" value="${jdbc.user}"></property>
<property name="password" value="${jdbc.password}"></property>
</bean>
<!-- 配置用于创建SqlSessionFactory的工厂bean -->
<bean class="org.mybatis.spring.SqlSessionFactoryBean">
<!-- 设置MyBatis配置文件的路径（可以不设置） -->
<property name="configLocation" value="classpath:mybatis-config.xml">
</property>
<!-- 设置数据源 -->
<property name="dataSource" ref="dataSource"></property>
<!-- 设置类型别名所对应的包 -->
<property name="typeAliasesPackage" value="com.tinstu.pojo">
</property>
<!--
设置映射文件的路径
若映射文件所在路径和mapper接口所在路径一致，则不需要设置
-->
<!--
<property name="mapperLocations" value="classpath:mapper/*.xml">
</property>
-->
</bean>
<!--
配置mapper接口的扫描配置
由mybatis-spring提供，可以将指定包下所有的mapper接口创建动态代理
并将这些动态代理作为IOC容器的bean管理
-->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.tinstu.mapper"></property>
</bean>
</beans>6.添加日志配置文件 logback.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration debug="false">
<!--定义日志文件的存储地址 logs为当前项目的logs目录 还可以设置为../logs -->
<property name="LOG_HOME" value="logs" />
<!--控制台日志， 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>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50}
- %msg%n</pattern>
</encoder>
</appender>
<!--myibatis 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 -->
<root level="DEBUG">
<appender-ref ref="STDOUT" />
</root>
</configuration>测试:
package com.tinstu.test;
import com.tinstu.mapper.UserMapper;
import com.tinstu.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
import java.util.List;
@SpringJUnitConfig(locations = "classpath:applicationContext.xml")
public class MapperTest {
@Autowired
private UserMapper userMapper;
@Test
public void test1(){
List<User> list = userMapper.getAll();
for(User user: list){
System.out.println(user);
}
}
}
加入MyBatisPlus
1.修改applicationContext.xml
<!-- 配置用于创建SqlSessionFactory的工厂bean --> <bean class="org.mybatis.spring.SqlSessionFactoryBean">
修改为:
<!-- 此处使用的是MybatisSqlSessionFactoryBean --> <bean class="com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean">
此处使用的是MybatisSqlSessionFactoryBean
经观察，目前bean中配置的属性和SqlSessionFactoryBean一致
MybatisSqlSessionFactoryBean是在SqlSessionFactoryBean的基础上进行了增强
即具有SqlSessionFactoryBean的基础功能，又具有MyBatis-Plus的扩展配置
具体配置信息地址：https://baomidou.com/pages/56bac0/#%E5%9F%BA%E6%9C%AC%E9%85%8D%E7%BD%AE
2.创建mapper接口
public interface UsermapperP extends BaseMapper<User> {
}
BaseMapper是MyBatis-Plus提供的基础mapper接口，泛型为所操作的实体类型，其中包含
CRUD的各个方法，我们的mapper继承了BaseMapper之后，就可以直接使用BaseMapper所提
供的各种方法，而不需要编写映射文件以及SQL语句，大大的提高了开发效率
测试:
@SpringJUnitConfig(locations = "classpath:applicationContext.xml")
public class MapperTest {
@Autowired
private UsermapperP usermapperP;
@Test
public void test2(){
User a = usermapperP.selectById(1);
System.out.println(a);
}
总结
在Spring整合MyBatis中加入了MyBatis-Plus后，我们就可以使用MyBatis-Plus所提供的BaseMapper实现CRUD，并不需要编写映射文件以及SQL语句
但是若要自定义SQL语句，仍然可以编写映射文件而不造成任何影响因为MyBatis-Plus只做增强，而不做改变
阅读剩余
版权声明：
作者：Tin
链接：http://www.tinstu.com/1456.html
文章版权归作者所有，未经允许请勿转载。
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