java.lang.ClassCastException：无法强制转换java.util.LinkedHashMap

JavaScript的

$.ajax({ headers : { 'Accept' : 'application/json' , 'Content-Type' : 'application/json' }, url : "/realgrid/product/addOd.do", type : "post", data : JSON.stringify(JsonOrderDetailValues), dataType : "json", success : function(data){ var json = eval(data); if (json.result == 1) { alert("insert."); }else if(json.result == 2){ alert("update.") }else { alert("error."); } }, error : function(request,status,error){ alert("code:"+request.status+"\n"+"error:"+error); } }); 

执行console.log（JsonOrderDetailValues）

 [Object, Object, Object, Object] 0: Object categoryCode: "AC-MV" categoryName: undefined costPrice: 168050 date: undefined modelCode: "YP-GB70" modelName: undefined no: 1 number: "201309120932" total: 88 totalPrice: 14788400 typeCode: "AV" typeName: undefined unitPrice: 294500 __proto__: Object 1: Object 2: Object 3: Object 

java spring Controller

  @RequestMapping (value="/addOd.do",method=RequestMethod.POST) public ModelAndView addOdMaster(@RequestBody List od){ //java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast System.out.println(od.get(0).getNumber()); Map result = new HashMap(); result.put("result", 0); return new ModelAndView("jsonView",result); } 

VO

 public class OrderDetails { private String number; private int no; private String typeCode; private String categoryCode; private String modelCode; private int total; private int costPrice; private int unitPrice; private int totalPrice; public int getTotalPrice() { return totalPrice; } public void setTotalPrice(int totalPrice) { this.totalPrice = totalPrice; } public String getNumber() { return number; } public void setNumber(String number) { this.number = number; } public int getNo() { return no; } public void setNo(int no) { this.no = no; } public String getTypeCode() { return typeCode; } public void setTypeCode(String typeCode) { this.typeCode = typeCode; } public String getCategoryCode() { return categoryCode; } public void setCategoryCode(String categoryCode) { this.categoryCode = categoryCode; } public String getModelCode() { return modelCode; } public void setModelCode(String modelCode) { this.modelCode = modelCode; } public int getTotal() { return total; } public void setTotal(int total) { this.total = total; } public int getCostPrice() { return costPrice; } public void setCostPrice(int costPrice) { this.costPrice = costPrice; } public int getUnitPrice() { return unitPrice; } public void setUnitPrice(int unitPrice) { this.unitPrice = unitPrice; } } 

错误信息

 FATAL: Servlet.service() for servlet [dispatcher] in context with path [/realgrid] threw exception [Request processing failed; nested exception is java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.realgrid.productControl.model.OrderDetails] with root cause java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.realgrid.productControl.model.OrderDetails at com.realgrid.productControl.controller.ProductControlController.addOdMaster(ProductControlController.java:181) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) at javax.servlet.http.HttpServlet.service(HttpServlet.java:641) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:395) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:250) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) 

为什么不？

Answer 1

在旧版本的Spring中，Spring无法（或者更确切地说不会）确定这一点

 @RequestBody List od 

有一个generics类型的OrderDetails ，因此Jackson（JSON反序列化器）将使用LinkedHashMap作为默认类型。 类型安全性将像您的情况一样中断，因为所有这整个请求处理调用（ @RequestMapping方法及其参数）都是通过reflection完成的。

这些版本的解决方案是创建自己的类型

 public class OrderDetailsList extends ArrayList {} 

并将其用作参数

 @RequestBody OrderDetailsList od 

（或升级到Spring 4.）