報錯信息：

### Error querying database. ?Cause: org.apache.ibatis.reflection.ReflectionException: Could not set property 'username' of 'class com.wfion.entity.User' with value 'demo' Cause: org.apache.ibatis.reflection.ReflectionException: There is no setter for property named 'username' in 'class com.wfion.entity.User'

### The error may exist in com/wfion/config/sqlxml/User.xml

### The error may involve User.loginquery

### The error occurred while handling results

### SQL: select ID,USERNAME,PASSWORD from USER where USERNAME=?

config配置文件;

<?xml?version="1.0"?encoding="UTF-8"??>
<!--

???????Copyright?2009-2016?the?original?author?or?authors.

???????Licensed?under?the?Apache?License,?Version?2.0?(the?"License");
???????you?may?not?use?this?file?except?in?compliance?with?the?License.
???????You?may?obtain?a?copy?of?the?License?at

??????????http://www.apache.org/licenses/LICENSE-2.0

???????Unless?required?by?applicable?law?or?agreed?to?in?writing,?software
???????distributed?under?the?License?is?distributed?on?an?"AS?IS"?BASIS,
???????WITHOUT?WARRANTIES?OR?CONDITIONS?OF?ANY?KIND,?either?express?or?implied.
???????See?the?License?for?the?specific?language?governing?permissions?and
???????limitations?under?the?License.

-->
<!DOCTYPE?configuration
????PUBLIC?"-//mybatis.org//DTD?Config?3.0//EN"
????"http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>
	<!--?
??<settings>
????<setting?name="useGeneratedKeys"?value="false"/>
????<setting?name="useColumnLabel"?value="true"/>
??</settings>

??<typeAliases>
????<typeAlias?alias="UserAlias"?type="com.wfion.entity.User"/>
??</typeAliases>
-->
??<environments?default="development">
????<environment?id="development">
??????<transactionManager?type="JDBC">
????????<property?name=""?value=""/>
??????</transactionManager>
??????<dataSource?type="UNPOOLED">
????????<property?name="driver"?value="com.mysql.jdbc.Driver"/>
????????<property?name="url"?value="jdbc:mysql://localhost:3306/autodistribute"/>
????????<property?name="username"?value="demo"/>
????????<property?name="password"?value="demo"/>
??????</dataSource>
????</environment>
??</environments>
?
??<mappers>
????<mapper?resource="com/wfion/config/sqlxml/User.xml"/>
??</mappers>

</configuration>

User.xml;

<?xml?version="1.0"?encoding="UTF-8"?>
<!--

???????Copyright?2009-2016?the?original?author?or?authors.

???????Licensed?under?the?Apache?License,?Version?2.0?(the?"License");
???????you?may?not?use?this?file?except?in?compliance?with?the?License.
???????You?may?obtain?a?copy?of?the?License?at

??????????http://www.apache.org/licenses/LICENSE-2.0

???????Unless?required?by?applicable?law?or?agreed?to?in?writing,?software
???????distributed?under?the?License?is?distributed?on?an?"AS?IS"?BASIS,
???????WITHOUT?WARRANTIES?OR?CONDITIONS?OF?ANY?KIND,?either?express?or?implied.
???????See?the?License?for?the?specific?language?governing?permissions?and
???????limitations?under?the?License.

-->
<!DOCTYPE?mapper
????PUBLIC?"-//mybatis.org//DTD?Mapper?3.0//EN"
????"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper?namespace="User">
??<!--?type是配置的類，id是自定義的resultMap名稱?-->
??<resultMap?type="com.wfion.entity.User"?id="UserResult">
????<id?column="ID"?jdbcType="INTEGER"?property="id"/>
????<result?column="USERNAME"?jdbcType="VARCHAR"?property="username"/>
????<result?column="PASSWORD"?jdbcType="VARCHAR"?property="password"/>
??</resultMap>
??<!--?resultMap相同才會匹配到然后執行SQL語句?parameterType為注入對象類型??-->
??<select?id="loginquery"?parameterType="com.wfion.entity.User"?resultMap="UserResult">
????select?ID,USERNAME,PASSWORD?from?USER?where?USERNAME=#{username}
??</select>

</mapper>

User.java

package?com.wfion.entity;

public?class?User?{
	private?int?ID;
	private?String?USERNAME;
	private?String?PASSWORD;
	public?int?getID()?{
		return?ID;
	}
	public?void?setID(int?iD)?{
		ID?=?iD;
	}
	public?String?getUSERNAME()?{
		return?USERNAME;
	}
	public?void?setUSERNAME(String?uSERNAME)?{
		USERNAME?=?uSERNAME;
	}
	public?String?getPASSWORD()?{
		return?PASSWORD;
	}
	public?void?setPASSWORD(String?pASSWORD)?{
		PASSWORD?=?pASSWORD;
	}
	
}

UserDao.java

package?com.wfion.dao;

import?java.io.IOException;
import?java.sql.Connection;
import?java.sql.DriverManager;
import?java.sql.PreparedStatement;
import?java.sql.ResultSet;
import?java.sql.SQLException;

import?org.apache.ibatis.session.SqlSession;

import?com.wfion.db.DbAccess;
import?com.wfion.entity.User;

/**
?*?和User相關的數據庫操作
?*
?*/
public?class?UserDao?{
	/**
	?*?處理用戶登錄判斷
	?*/
	public?User?loginQuery(String?username){
		DbAccess?dbAccess=new?DbAccess();
		SqlSession?sqlSession=null;
		User?user=new?User();
		user.setUSERNAME(username);
		try?{
			sqlSession=dbAccess.getSqlSession();
			user=sqlSession.selectOne("User.loginquery",username);
			//通過sqlSession執行sql語句
		}?catch?(IOException?e)?{
			//?TODO?Auto-generated?catch?block
			e.printStackTrace();
		}?finally{
			if(sqlSession!=null){
				sqlSession.close();
			}
		}
		return?user;
	}
	
	
	
	/**
	?*?處理用戶登錄判斷
	?*/
//	public?User?loginQuery(String?username){
//		User?user=null;
//		try?{
//			Class.forName("com.mysql.jdbc.Driver");
//			Connection?conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/autodistribute","demo","demo");
//			String?sql="select?ID,USERNAME,PASSWORD?from?USER?where?USERNAME=?";
//			PreparedStatement?statement=conn.prepareStatement(sql);
//			statement.setString(1,?username);
//			ResultSet?rs=statement.executeQuery();
//			while(rs.next()){
//				user=new?User();
//				user.setID(rs.getInt("ID"));
//				user.setUSERNAME(rs.getString("USERNAME"));
//				user.setPASSWORD(rs.getString("PASSWORD"));
//			}
//		}?catch?(ClassNotFoundException?e)?{
//			//?TODO?Auto-generated?catch?block
//			e.printStackTrace();
//		}?catch?(SQLException?e)?{
//			//?TODO?Auto-generated?catch?block
//			e.printStackTrace();
//		}
//		return?user;
//		
//	}
}

DbAccess.java

package?com.wfion.db;

import?java.io.IOException;
import?java.io.Reader;

import?org.apache.ibatis.io.Resources;
import?org.apache.ibatis.session.SqlSession;
import?org.apache.ibatis.session.SqlSessionFactory;
import?org.apache.ibatis.session.SqlSessionFactoryBuilder;



public?class?DbAccess?{
	public?SqlSession?getSqlSession()?throws?IOException{
		//通過配置文件獲取數據庫信息
		Reader?reader=Resources.getResourceAsReader("com/wfion/config/Configuration.xml");
		//通過配置文件構建一個SqlSessionFactory
		SqlSessionFactory?sqlSessionFactory=new?SqlSessionFactoryBuilder().build(reader);
		//通過SqlSessionFactory打開一個數據庫會話
		SqlSession?sqlSession=sqlSessionFactory.openSession();
		return?sqlSession;
	}
}

求科普啊，實例化也不行