mybatis中类属性和数据表字段不一致的解决方法

这几天一直在探究mybaits 简单的操作基本掌握了 但是如果数据库中的表名和实体类的类名中的字段 名称不一样 就会造成空指针异常

但是你打印集合中是否有元素 它会显示 有元素 但是如果继续输出属性就会报空指针异常

类的映射文件

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//ibatis.apache.org//DTD Mapper 3.0//EN" 
"http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd"> 
<mapper namespace="com.dragon.entity.User">
<!-- 配置orm映射 确保数据库中的列能和bean中的列相对应 -->
<resultMap type="User" id="user_orm">
<id property="userId" column="user_id"/>
<result property="userName" column="user_name"></result>
<result property="userPassword" column="user_password"></result>
</resultMap>
<!-- 查询语句 -->
<select id="selectAll_user" parameterType="User" resultMap="user_orm" >
SELECT user_id ,user_name ,user_password FROM UserInfo
</select>

</mapper> 

只要设置两个属性相关联 返回的resultMap相关连就可以了

类的属性

package com.dragon.entity;
import java.io.Serializable;
/**
* 用户实体类
* @author Administrator
*
*/
public class User implements Serializable {
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserPassword() {
return userPassword;
}
public void setUserPassword(String userPassword) {
this.userPassword = userPassword;
}
public static long getSerialversionuid() {
return serialVersionUID;
}
/**
 * 
 */
private static final long serialVersionUID = 1L;
private int userId;
private String userName;
private String userPassword;
public User() {
super();
}
} 

数据库中的表的字段

---------创建表
CREATE TABLE UserInfo (
 user_id number(5) primary key not null,
 user_name nvarchar2(50) not null,
 user_password nvarchar2(50) 
 );
commit;
insert into UserInfo values(1,'1001','111111');
insert into UserInfo values(2,'1002','111111');
insert into UserInfo values(3,'1003','111111');
insert into UserInfo values(4,'1004','111111');
insert into UserInfo values(5,'1005','111111');
commit;
SELECT * FROM UserInfo;

<wbr></wbr>