Mybatis-Plus 快速入门

MP是对Mybatis的开发简化，目前我们可以简单将其理解为MP封装了各种SQL语句。

这样一来我们在开发时便可以利用MP提供的BaseMapper接口完成对数据库的各种操作，而不是亲自编写Mapper接口，同时mapper.xml也变得不必要。

Spring+MP开发示例：

1、添加依赖：

<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>4.0.0modelVersion>
 
    <groupId>org.examplegroupId>
    <artifactId>MybatisPlusartifactId>
    <packaging>pompackaging>
    <version>1.0-SNAPSHOTversion>
    <modules>
        <module>增强原生Mybatismodule>
    modules>
 
    <properties>
        <maven.compiler.source>8maven.compiler.source>
        <maven.compiler.target>8maven.compiler.target>
    properties>
 
    <dependencies>
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-contextartifactId>
            <version>5.0.5.RELEASEversion>
        dependency>
 
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-testartifactId>
            <version>5.0.5.RELEASEversion>
        dependency>
 
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-webartifactId>
            <version>5.0.5.RELEASEversion>
        dependency>
 
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-webmvcartifactId>
            <version>5.0.5.RELEASEversion>
        dependency>
 
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-jdbcartifactId>
            <version>5.0.5.RELEASEversion>
        dependency>
 
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-txartifactId>
            <version>5.0.5.RELEASEversion>
        dependency>
 
        
        <dependency>
            <groupId>com.baomidougroupId>
            <artifactId>mybatis-plusartifactId>
            <version>3.5.1version>
        dependency>
 
        
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>8.0.26version>
        dependency>
 
        
        <dependency>
            <groupId>com.alibabagroupId>
            <artifactId>druidartifactId>
            <version>1.2.8version>
        dependency>
 
        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <version>1.18.22version>
        dependency>
 
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.13.1version>
        dependency>
 
        <dependency>
            <groupId>log4jgroupId>
            <artifactId>log4jartifactId>
            <version>1.2.17version>
        dependency>
 
    dependencies>
 
    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <artifactId>maven-compiler-pluginartifactId>
                    <version>3.8.0version>
                plugin>
            plugins>
        pluginManagement>
    build>
 
project>

 

2、建立数据库及表：

 

3、配置applicationContext.xml：

<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
                           http://www.springframework.org/schema/context/spring-context.xsd">
 
    
    <context:property-placeholder location="classpath:jdbc.properties"/>
 
    
    <bean name="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${driverClass}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${user}"/>
        <property name="password" value="${password}"/>
    bean>
 
    
    <bean id="sqlSessionFactory" class="com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean">
        
        <property name="dataSource" ref="dataSource">property>
        
        <property name="typeAliasesPackage" value="pojo"/>
    bean>
 
    
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="mapper"/>
    bean>
 
beans>

配置SessionFactory时使用MP提供的MybatisSqlSessionFactoryBean：

"com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean"

4、编写User对象与Mapper接口

User:

package pojo;
 
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
 
@Data
@NoArgsConstructor
@AllArgsConstructor
@TableName("tb_user")
public class User {
    //lombok注解自动为对象创建各种方法
    private Long id;
    private String userName;
    private String password;
    private String name;
    private Integer age;
    private String email;
 
}

其中 @Date 、@NoargsConstructor 、 @AllArgsConstructor 为lombok提供的注解，自动为User对象编写set、get、构造体等方法：

Mapper接口：

package mapper;
 
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import pojo.User;
 
public interface UserMapper extends BaseMapper {//继承BaseMapper后便可使用其封装的诸多方法
}

BaseMapper中封装了诸多方法，继承后直接引用即可：

 

5、其他配置文件：

jdbc.properties；

log4j.properties。

6、测试：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath*:applicationContext.xml"})
public class test {
    @Autowired
    private UserMapper mapper;
 
    @Test
    public void test() {
 
        List list = mapper.selectList(null);
        for(User user: list ) {
            System.out.println(user);
        }
 
    }
}

运行成功：