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【笔记】MyBatis参数处理方式

 2 years ago
source link: https://feiju12138.github.io/2022/09/28/MyBatis%E5%8F%82%E6%95%B0%E5%A4%84%E7%90%86%E6%96%B9%E5%BC%8F/
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MyBatis参数处理方式

多个参数的处理方式

  • 当Java向MyBatis传递了一组参数时，根据参数的传递顺序，MyBatis会自动创建一个Map集合来存储参数
  • 每个参数会向Map中创建2个键值对，第一个参数的键名分别是arg0和param1，值为参数值，以此类推

src/main/java/com/mapper/UserMapper.java

void test(int id, String name)

src/main/resources/com/mapper/UserMapper.xml

<select id="test">
    SELECT * FROM user
    WHERE id = #{arg0}
    AND name = #{arg1};
</select>

<select id="test">
    SELECT * FROM user
    WHERE id = #{param1}
    AND name = #{param2};
</select>
  • 可以通过@Param()注解修改Map中以arg开头的键名

src/main/java/com/mapper/UserMapper.java

void test(@Param("id") int id, @Param("name") String name)

src/main/resources/com/mapper/UserMapper.xml

<select id="test">
    SELECT * FROM user
    WHERE id = #{id}
    AND name = #{name};
</select>

<select id="test">
    SELECT * FROM user
    WHERE id = #{param1}
    AND name = #{param2};
</select>

单个数据的处理方式

  • 无论什么类型的数据传递到MyBatis事时，都会被MyBatis封装为Map集合
  • 如果是以下类型，默认会自动封装Map集合
    • POJO类型
    • Map集合

Collection的封装方式

  • 键为arg0，值为集合
  • 键为collection，值为集合

List的封装方式

  • 键为arg0，值为集合
  • 键为collection，值为集合
  • 键为list，值为集合

数组的封装方式

  • 键为arg0，值为数组
  • 键为array，值为数组

哔哩哔哩——黑马程序员


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