8/4/2018 11:03:14 PM

今天测试项目出现使用MyBatis select数据库查出有数据 但返回对象为null

mybatis配置文件:

 <!-- 根据主键ID查询订单信息-->
<select id="getPayOrderId" parameterType="java.lang.String" resultType="PayOrder">
    SELECT
    a.ID AS 'id',
    a.USER_ID AS 'user_id',
    a.MERCHANT_ID AS 'merchant_id',
    a.PAY_ORDER_ID AS 'pay_order_id',
    a.USER_NAME AS 'user_name',
    a.MERCHANT_NAME AS 'merchant_name',
    a.PAY_TYPE AS 'pay_type',
    a.PAY_MONEY AS 'pay_money',
    a.PAY_ZD_MONEY AS 'pay_zd_money',
    a.PAY_BALANCE_MONEY AS 'pay_balance_money',
    a.PAY_APPRECIATION_MONEY AS 'pay_appreciation_money',
    a.PAY_BANKCARD_MONEY AS 'pay_bankcard_money',
    a.STATUS AS 'status',
    a.FINISH_TIME AS 'finish_time',
    a.CREATE_TIME AS 'create_time'
    FROM
    pay_order a
    WHERE a.ID = #{_id,jdbcType=VARCHAR}
</select>

对应查询的java实体类:

public class PayOrder  {

private static final long serialVersionUID = 1L;
private String id;                       
private String user_id;                  
private String merchant_id;              
private String pay_order_id;             
private String pay_type;                 
private String pay_money;                
private String pay_zd_money;             
private String pay_balance_money;        
private String pay_appreciation_money;   
private String pay_bankcard_money;       
private String status;                  
private Date create_time;                
private Date finish_time;               
private String merchant_name;            
private String user_name;                
private String pay_pwd;                  

//自动生成set、get方法
｝

之后就出现通过ID进行查询返回对象一直为null,但是自己的sql语句在数据库中测试时显示有数据。

解决办法

1.修改Dao对应的xml配置

    <resultMap id="setPayOrder" type="order.PayOrder">
    <id column="ID" property="id" jdbcType="VARCHAR"/>
    <result column="USER_ID" property="user_id" jdbcType="VARCHAR"/>
    <result column="MERCHANT_ID" property="merchant_id" jdbcType="VARCHAR"/>
    <result column="PAY_ORDER_ID" property="pay_order_id" jdbcType="VARCHAR"/>
    <result column="USER_NAME" property="user_name" jdbcType="VARCHAR"/>
    <result column="MERCHANT_NAME" property="merchant_name" jdbcType="VARCHAR"/>
    <result column="PAY_TYPE" property="pay_type" jdbcType="VARCHAR"/>
    <result column="PAY_MONEY" property="pay_money" jdbcType="VARCHAR"/>
    <result column="PAY_ZD_MONEY" property="pay_zd_money" jdbcType="VARCHAR"/>
    <result column="PAY_BALANCE_MONEY" property="pay_balance_money" jdbcType="VARCHAR"/>
    <result column="PAY_APPRECIATION_MONEY" property="pay_appreciation_money" jdbcType="VARCHAR"/>
    <result column="PAY_BANKCARD_MONEY" property="pay_bankcard_money" jdbcType="VARCHAR"/>
    <result column="STATUS" property="status" jdbcType="VARCHAR"/>
    <result column="CREATE_TIME" property="create_time" jdbcType="TIMESTAMP"/>
    <result column="FINISH_TIME" property="finish_time" jdbcType="TIMESTAMP"/>
</resultMap>


<!-- 根据主键ID查询订单信息-->
<select id="getPayOrderId" parameterType="java.lang.String" resultMap="setPayOrder">
    SELECT
    a.ID AS 'id',
    a.USER_ID AS 'user_id',
    a.MERCHANT_ID AS 'merchant_id',
    a.PAY_ORDER_ID AS 'pay_order_id',
    a.USER_NAME AS 'user_name',
    a.MERCHANT_NAME AS 'merchant_name',
    a.PAY_TYPE AS 'pay_type',
    a.PAY_MONEY AS 'pay_money',
    a.PAY_ZD_MONEY AS 'pay_zd_money',
    a.PAY_BALANCE_MONEY AS 'pay_balance_money',
    a.PAY_APPRECIATION_MONEY AS 'pay_appreciation_money',
    a.PAY_BANKCARD_MONEY AS 'pay_bankcard_money',
    a.STATUS AS 'status',
    a.FINISH_TIME AS 'finish_time',
    a.CREATE_TIME AS 'create_time'
    FROM
    pay_order a
    WHERE a.ID = #{_id,jdbcType=VARCHAR}
</select>

问题原因：实体类中属性与表中字段不一致时，添加resultMap进行重新关联实体类。