Questions about MyBatis There is no getter for property named ' User_name ' in ' Class Com.bky.model. Instance class '

Now the popular SSM (Spring + struts2 + myBatis) Persistence layer MyBatis is the need to configure the mapper, found a demo connection database is MySQL then modified to become a connection to Oracle

When everything's ready to run, it's time to do the insert operation. My table is b field is ID, user_name, password instance class field is ID, Username,password,

Here is a user_name and username had a headache for the afternoon, and later found the fishy,

There is no getter for property named ' User_name ' in ' Class com.bky.model.b '

Code:

Entity class B

Package Com.bky.model;public class B {    private Long ID;    Private String userName;        private String password;    Public Long GetId () {return ID;} public void SetId (Long id) {this.id = id = = null? Null:id;} Public String GetUserName () {return userName;} public void Setusername (String userName) {this.username = UserName;} Public String GetPassword () {return password;} public void SetPassword (String password) {this.password = password = = null? Null:password.trim ();}}

Mapper. xml

<?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.bky.dao.BMapper" >  <resultmap id= "Baseresultmap" type= "com.bky.model.b" >    <id column= "id" property= "id" jdbctype= "INTEGER"/>    <result column= "user_name" property= "UserName" jdbctype= "varchar"/>    <result column= "PASSWORD" property= "PASSWORD" jdbctype= "varchar"/>  </ resultmap>  <sql id= "Base_column_list" >    ID, user_name, PASSWORD  </sql>

<span style= "White-space:pre" ></span><!--Let's focus on this.

<span style= "White-space:pre" ></span>user_name is a table field and behind <span style= "font-family:arial, Helvetica, Sans-serif; " >#{user_name,jdbctype=varchar} Here is wrong should be written </span><span style= "Font-family:arial, Helvetica, Sans-serif;" >#{username,jdbctype=varchar} should be a property value ah look for a good bitter ah, this is a waste of the afternoon, but still solved, a lot of people at the beginning of Baidu is the property name is wrong, there is no set/get  summary to share this There is a general error in this case. Hope can help beginners </span>

<span style= "White-space:pre" ></span>-->

  <insert id= "insertselective" parametertype= "com.bky.model.b" >    insert INTO B (User_name,password) VALUES (#{ User_name,jdbctype=varchar},#{password,jdbctype=varchar})  </insert>    <update id= " Updatebyprimarykey "parametertype=" com.bky.model.b ">    update B    set user_name = #{user_name,jdbctype= VARCHAR},      PASSWORD = #{password,jdbctype=varchar}    where id = #{id,jdbctype=integer}  </update>    <select id= "GetAll" resultmap= "Baseresultmap" >  SELECT * from B  </select></mapper>

Questions about MyBatis There is no getter for property named ' User_name ' in ' Class Com.bky.model. Instance class '