java.lang.ClassCaption: java.lang.Long cannot be cast to java.lang.String
问题背景
service传参调用mapper，报错：
[09 17:56:54,707 DEBUG] [http-nio-8081-exec-9] handler.SimpleMappingExceptionResolver - Resolving to view 'WEB-INF/500' for exception of type [java.lang.ClassCastException], based on exception mapping [java.lang.Throwable]
[09 17:56:54,707 DEBUG] [http-nio-8081-exec-9] handler.SimpleMappingExceptionResolver - Exposing Exception as model attribute 'exception'
[09 17:56:54,707 DEBUG] [http-nio-8081-exec-9] servlet.DispatcherServlet - Handler execution resulted in exception - forwarding to resolved error view: ModelAndView: reference to view with name 'WEB-INF/500'; model is {exception=java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String}
java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String
//加判断，如果已经使用，无法删除Map<String, String> template = detectionTemplateMapper.queryTypeById(id);
//查询异常工单是否使用if(adminOrderMapper.findCountByDetection(template.get("id").toString(),template.get("detectionType"))>0){return 0;}
<select id="queryTypeById" resultType="java.util.HashMap">SELECT id,detectionType,ordernum,isSingle,isMainType,remark from work_detection_template where id=#{0}</select>
问题分析
因为查询的id数据库是int类型，返回结果为Long类型，所以想着toString即可，结果还是报错，改为String.valueOf()后不报错了。
问题总结
转换字符串，尽量使用valueOf()方法吧
/*** Returns the string representation of the {@code Object} argument.** @param obj an {@code Object}.* @return if the argument is {@code null}, then a string equal to*{@code "null"}; otherwise, the value of*{@code obj.toString()} is returned.* @seejava.lang.Object#toString()*/public static String valueOf(Object obj) {return (obj == null) ? "null" : obj.toString();}
