zoukankan      html  css  js  c++  java
  • MyBatis入参方式

    1.传递单参数的形式

      MyBatis会自动进行参数的赋值

      如:

    public  void  deletePerson(Integer id);  //接口
    <!-- mapper配置文件-->
      <delete id="deletePerson" parameterType="int">
    
          delete from person where id=#{parameter1} <!-- #{}里面写任何值都能取到值-->
        
      </delete>

    2.传递多个参数(mapper不会自动赋值)

      a.使用Map接口(不推荐)

    public Person getPersonByNameAndGender(Map<String,Object> param);//接口
      <select id="getPersonByNameAndGender" resultType="person">
    
        select * from person where username=#{username} and gender=#{gender}
        
        <!--#{}里面填写Map的key值-->
      </select>

      b.使用javaBean(封装pojo类)传递参数(传递的参数多于5)

    //将要传递的参数封装在一个对象中
    public Person getPersonByNameAndGender(Person person);
      <select id="getPersonByNameAndGender" resultType="person">
    
        select * from person where username=#{username} and gender=#{gender}
    
        <!--#{}里填写person对象里面的属性-->
      </select>

      c.使用注解@param传递参数(传递的参数少于5)

    public Person getPersonByNameAndGender(@Param("username") String username, @Param("gender") String gender);
      <select id="getPersonByNameAndGender" resultType="person">
    
        select * from person where username=#{username} and gender=#{gender}
    
      </select>

    3.传递的参数是个collection、list、array

      使用注解@param

     public Person getPersonByCollection(@Param("test") int[] ids);
    <select id="getPersonByCollection" resultType="person">
    
        select * from person where id=#{test[0]}
      </select>

      可使用foreach标签读取参数

    public List<Person> getPersonsByIds(@Param("test")int[] ids);
      <select id="getPersonsByIds" resultType="person">
    
        select * from person where id in
    
        <foreach collection="test" item="id" index="i" open="(" close=")" separator=",">
          #{id}
        </foreach>
    
    <!--collection表示选取的集合,item表示当前遍历的对象,index表示当前遍历的索引-->
    <!--若test这个数组里面为test[]{1,2,3},则上面的sql语句相当于select * from person id in (1,2,3,4)-->
      </select>
  • 相关阅读:
    Codeforces Round #719 (Div. 3) 题解
    Codeforces Global Round 14 A~F题解
    AtCoder Beginner Contest 199 题解
    Codeforces Round #716 (Div. 2) A~D 题解
    Codeforces Round #713 (Div. 3) 题解
    Codeforces Round #712 (Div. 2) A~E 题解
    CodeCraft-21 and Codeforces Round #711 (Div. 2) A~E 题解
    CF839 D 莫比乌斯反演
    java存大数和高精度浮点数(BigInteger与BigDecimal)
    java科学计算常用方法(Math)
  • 原文地址:https://www.cnblogs.com/shouyaya/p/12791309.html
Copyright © 2011-2022 走看看