MyBatis 4种参数绑定方式（默认参数绑定，@Param注解参数绑定，parameterType参数绑定，自定义类参数绑定）

        默认Mapper映射文件中的变量名只能是 #{arg0}，#{arg1} ...或者是#{param1}，#{param2} ...。其中arg变量名从0开始，param变量名从1开始。

    
    List getUserList(String username,String password);

        第一种变量命名方式：

    
        SELECT *
        from users
        where username  = #{arg0} and password=#{arg1}
    

        第二种变量命名方式：

    
        SELECT *
        from users
        where username  = #{param1} and password=#{param2}
     
2 @Param注解参数绑定 
2.1 UserMapper.java 
    
    List getUserList(@Param("username") String username, @Param("password") String password);
 
2.2 UserMapper.xml 
    
        SELECT *
        from users
        where username  = #{username} and password=#{password}
    

    
    List getUserList(String username,String password);

    
        SELECT *
        from users
        where username  = #{username} and password=#{password}
     
4 自定义类参数绑定 
4.1 UserEntity 
package com.entity;

import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;


@Data
@TableName("users")
public class UserEntity {
    
    @TableField("username")
    @TableId
    private String username;
    
    @TableField("password")
    private String password;
}
 
4.2 UserMapper.java 
    
    List getUserList(UserEntity userEntity);
 
4.3 UserMapper.xml 
    
        SELECT *
        from users
        where username  = #{username} and password=#{password}