MyBatisPlus--简单使用

创建Maven工程，引入依赖

	<dependencies>
        <!-- mybatis-plus插件 -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus</artifactId>
            <version>3.1.1</version>
        </dependency>
        <!-- MySQL -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <!-- 连接池 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.11</version>
        </dependency>

        <!-- 简化bean代码的工具包 -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
            <version>1.18.4</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.6.4</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

配置

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

mybatis-config.xml

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/mbplus?useUnicode=true&amp;characterEncoding=utf8&amp;autoReconnect=true&amp;allowMultiQueries=true&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        <mapper resource="UserMapper.xml"/>
    </mappers>
</configuration>

User实体类

@Data
@NoArgsConstructor
@AllArgsConstructor
@TableName("tb_user") //指定数据库的表名
public class User {

    private Long id;
    private String userName;
    private String password;
    private String name;
    private Integer age;
    private String email;
}

UserMapper和UserMapper.xml

//继承BasseMapper并指定泛型
public interface UserMapper extends BaseMapper<User> {

    List<User> findAll();
}

<?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="pers.zhang.mapper.UserMapper">

    <select id="findAll" resultType="pers.zhang.pojo.User">
        SELECT *
        FROM tb_user
    </select>

</mapper>

测试

首先测试自己写的SQL：

@Test
    public void testFindAll() throws IOException {
        String config = "mybatis-config.xml";
        InputStream i = Resources.getResourceAsStream(config);

        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(i);

        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        //测试
        List<User> all = userMapper.findAll();
        for (User u : all)
            System.out.println(u);
    }

控制台输出：

[main] [pers.zhang.mapper.UserMapper.findAll]-[DEBUG] ==>  Preparing: SELECT * FROM tb_user 
[main] [pers.zhang.mapper.UserMapper.findAll]-[DEBUG] ==> Parameters: 
[main] [pers.zhang.mapper.UserMapper.findAll]-[DEBUG] <==      Total: 5
User(id=1, userName=null, password=123456, name=张三, age=18, email=test1@qq.com)
User(id=2, userName=null, password=123456, name=李四, age=28, email=test2@qq.com)
User(id=3, userName=null, password=123456, name=王五, age=38, email=test3@qq.com)
User(id=4, userName=null, password=123456, name=赵六, age=48, email=test4@qq.com)
User(id=5, userName=null, password=123456, name=小强, age=58, email=test5@qq.com)

测试MyBatis-Plus提供的方法：

@Test
    public void testMP() throws IOException {
        String config = "mybatis-config.xml";
        InputStream i = Resources.getResourceAsStream(config);

        //使用MP中的MybatisSqlSessionFactoryBuilder进行构建
        SqlSessionFactory sqlSessionFactory = new MybatisSqlSessionFactoryBuilder().build(i);

        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        //测试mybatis-plus提供的selectList()方法
        List<User> all = userMapper.selectList(null);
        for (User u : all)
            System.out.println(u);
    }

控制台打印：

[main] [pers.zhang.mapper.UserMapper.selectList]-[DEBUG] ==>  Preparing: SELECT id,user_name,password,name,age,email FROM tb_user 
[main] [pers.zhang.mapper.UserMapper.selectList]-[DEBUG] ==> Parameters: 
[main] [pers.zhang.mapper.UserMapper.selectList]-[DEBUG] <==      Total: 5
User(id=1, userName=zhangsan, password=123456, name=张三, age=18, email=test1@qq.com)
User(id=2, userName=lisi, password=123456, name=李四, age=28, email=test2@qq.com)
User(id=3, userName=wangwu, password=123456, name=王五, age=38, email=test3@qq.com)
User(id=4, userName=zhaoliu, password=123456, name=赵六, age=48, email=test4@qq.com)
User(id=5, userName=xiaoqiang, password=123456, name=小强, age=58, email=test5@qq.com)

结果一致，但SQL不同，SQL是继承BaseMapper得来的，由MyBatis-Plus提供的。