Mybatis获取参数的几种方式

朱雀 2024-04-08 11:27 84阅读 0赞

#### Mybatis获取参数的几种方式 ####

这里以UserDao实现User类的方法为例，以代码及注释的方式展现

package com.qcw.mybatis.mapper;
    
    import com.qcw.mybatis.pojo.User;
    import org.apache.ibatis.annotations.Param;
    
    import java.util.Map;
    
    /**
     *mybatis获取参数的几种方式：#{}和${}
     * -对于一下几种获取参数的方法可直接归结为两种：实体类类型的参数 和 参数上设置@param注解
     * 前三种方法都可以用第五种方法实现更为简便
     *
     * 1.若mapper接口方法的参数为单个的字面量类型，此时可以通过#{},${}以任意内容获取参数值
     *
     * 2.若mapper接口方法的参数为多个字面量类型
     *   -此时mybatis会将参数放在map集合，以两种方式存储数据，
     *   -以arg0,arg1...为键，以参数为值;或者以param1，param2...为键，以参数为值
     *   -因此，只需要通过#{}，${}访问map集合的键,来获取相应的值
     *
     * 3.若mapper接口方法的参数为map集合类型的参数，
     *   -只需要通过#{}，${}访问map集合的键,就可以获取相应的值
     *
     * 4.若mapper接口方法的参数为实体类类型的参数
     *   -只需要通过#{}，${}访问实体类中的属性名，就可以获取相应的值
     *
     * 5.可以在mapper接口方法的参数上设置@param注解，此时mybatis会将这些参数放在map中
     * 以两种方式进行存储 (相比2，3两种方法更为简便,所以更建议使用代替前三种方法)
     *   -以@param注解的value值为键，以参数为值，或者以param1，param2..为键，以参数为值
     */
    public interface UserMapper {
        
    
        //根据用户名查询用户信息
        User getUserByUsername(String username);
    
        //验证登录
        User checkLogin(String username, String password);
    
        //验证登录(以map集合来作为参数)
        User checkLoginByMap(Map<String,Object> map);
    
        //添加用户信息
        void insertUser(User user);
    
        //验证登录，使用@Param注解
        User checkLoginByParam(@Param("username") String username, @Param("password") String password);
    }

<?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.qcw.mybatis.mapper.UserMapper">
    
        <select id="getUserByUsername" resultType="User">
            select * from t_user where username = #{
        username}
        </select>
    
    
        <select id="checkLogin" resultType="User">
            select * from t_user where username = #{
        param1} and password = #{
        param2}
        </select>
    
        <select id="checkLoginByMap" resultType="User">
            select * from t_user where username = #{
        username} and password = #{
        password}
        </select>
    
    
        <insert id="insertUser">
            insert into t_user values(null ,#{
        username},#{
        password},#{
        age},#{
        gender},#{
        email})
        </insert>
    
    
        <select id="checkLoginByParam" resultType="User">
            select * from t_user where username = #{
        username} and password = #{
        password}
        </select>
    </mapper>

package com.qcw.mybatis.test;
    
    import com.qcw.mybatis.mapper.UserMapper;
    import com.qcw.mybatis.pojo.User;
    import com.qcw.mybatis.utils.SqlSessionUtil;
    import org.apache.ibatis.session.SqlSession;
    import org.junit.Test;
    
    import java.util.HashMap;
    import java.util.Map;
    
    
    public class ParameterTest {
        
    
        @Test
        public void getUserByUsernameTest(){
        
            SqlSession sqlSession = SqlSessionUtil.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    
            User user = mapper.getUserByUsername("wqc");
            System.out.println("user = " + user);
        }
    
        @Test
        public void checkLoginTest(){
        
            SqlSession sqlSession = SqlSessionUtil.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    
            User user = mapper.checkLogin("wqc", "12345");
            System.out.println("user = " + user);
        }
    
        @Test
        public void checkLoginByMapTest(){
        
            SqlSession sqlSession = SqlSessionUtil.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    
            Map<String,Object> map = new HashMap<>();
            map.put("username","wqc");
            map.put("password","12345");
    
            User user = mapper.checkLoginByMap(map);
            System.out.println("user = " + user);
    
        }
    
        @Test
        public void insertUserTest(){
        
            SqlSession sqlSession = SqlSessionUtil.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    
            User user = new User(null,"root","12357",26,"女","377@qq.com");
            mapper.insertUser(user);
            System.out.println("user = " + user);
        }
    
        @Test
        public void checkLoginByParamTest(){
        
            SqlSession sqlSession = SqlSessionUtil.getSqlSession();
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    
            User user = mapper.checkLoginByParam("wqc", "12345");
            System.out.println("user = " + user);
        }
    }

注：代码为本人学习记录，仅供参考