MyBatis的配置和简单使用

pom.xml

        
        
            org.mybatis
            mybatis
            3.5.7
        
        
        
            junit
            junit
            4.12
            test
        
        
        
            mysql
            mysql-connector-java
            5.1.3
        
        
        
            log4j
            log4j
            1.2.17
        
    

mybatis-config.xml

jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/MyBatis
jdbc.username=root
jdbc.password=root

log4j.xml 配置打印sql

UserMapper.xml

    
    
      insert into t_user values(null,'admin','123',23,'女','11222@qq.com')
    

    
    
        select * from t_user
    

UserMapper

public interface UserMapper {
   int insertUser();

   List getAllUser();
}

SqlSessionUtils

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class SqlSessionUtils {
    public static SqlSession getSqlSession() {
        SqlSession sqlSession = null;
        try {
            InputStream is = Resources.getResourceAsStream("mybatis-config.xml"); //创建SqlSessionFactoryBuilder对象
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
            // 创建SqlSession对象，此时通过SqlSession对象所操作的sql都会自动提交
            sqlSession = sqlSessionFactory.openSession(true);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return sqlSession;
    }
}

测试代码

 @Test
    public void testMyBatis() throws IOException {
        SqlSession sqlSession = SqlSessionUtils.getSqlSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        // 调用UserMapper接口中的方法，就可以根据UserMapper的全类名匹配元素文件，通过调用的方法名匹配 映射文件中的SQL标签，并执行标签中的SQL语句
        List result = userMapper.getAllUser();
        System.out.println(result);
        // sqlSession.commit(); 手动提交
    }

运行结果

若mapper接口中的方法参数为实体类对象时
${} ：拼接字符串，需要加单引号
#{} ：占位符

  
    
      insert into t_user values(null,#{username},#{password},#{age},#{sex},#{email})
    

调用

	@Test
    public void testMyBatis() throws IOException {
        SqlSession sqlSession = SqlSessionUtils.getSqlSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        // 调用UserMapper接口中的方法，就可以根据UserMapper的全类名匹配元素文件，通过调用的方法名匹配 映射文件中的SQL标签，并执行标签中的SQL语句
        int result = userMapper.insertUser(new User(-1, "admin", "123456", 18, "女", "111@qq.com"));
        System.out.println(result);
    }

使用@Param标识参数

可以通过@Param注解标识mapper接口中的方法参数

 

   
   select * from t_user where username = '${param1}' and password = #{param2}

测试

    @Test
    public void testMyBatis() throws IOException {
        SqlSession sqlSession = SqlSessionUtils.getSqlSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        User user = userMapper.getUserByLogin("admin","123456");
        System.out.println(user);
    }

注：传入一个指定key的map集合也可以，在xxxxMapper.xml通过用map集合的key也可以获取到参数。