在Spring Web Flow中上傳文件-錯誤處理？

Question

我正在使用Spring Webflow和org.springframework.web.multipart.commons.CommonsMultipartFile從網頁上載文件。 輸入表單通過驗證后，上傳工作正常。 當表單驗證失敗且Web Flow嘗試重新顯示頁面時，就會出現問題。 似乎它嘗試重新加載文件上載控件，它查找上載使用的臨時文件，但該文件不存在。 查看實際的MultipartFile.java源代碼，我看到以下注釋：

The temporary storages will be cleared at the end of request processing.

因此，與其重新顯示網絡表單，該應用程序還會在下面引發此錯誤。 在Web Flow內部處理此問題的最佳方法是什么（請記住，Web Flow無法為您提供與“常規” MVC相同的控制級別）。 我可以丟棄MultipartFile對象中的所有內容，但我不知道該將其初始化為什么。

這就是我現在得到的：

org.springframework.webflow.execution.repository.FlowExecutionRestorationFailureException: A problem occurred restoring the flow execution with key 'e1s5'
    at org.springframework.webflow.execution.repository.snapshot.SerializedFlowExecutionSnapshotFactory.restoreExecution(SerializedFlowExecutionSnapshotFactory.java:82)
    at org.springframework.webflow.execution.repository.snapshot.AbstractSnapshottingFlowExecutionRepository.restoreFlowExecution(AbstractSnapshottingFlowExecutionRepository.java:89)
    at org.springframework.webflow.execution.repository.impl.DefaultFlowExecutionRepository.getFlowExecution(DefaultFlowExecutionRepository.java:115)
    at org.springframework.webflow.executor.FlowExecutorImpl.resumeExecution(FlowExecutorImpl.java:168)
    at org.springframework.webflow.mvc.servlet.FlowHandlerAdapter.handle(FlowHandlerAdapter.java:183)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:920)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:816)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:801)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:165)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:203)
    at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:181)
    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:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:662)
Caused by: org.springframework.webflow.execution.repository.snapshot.SnapshotUnmarshalException: IOException thrown deserializing the flow execution stored in this snapshot -- this should not happen!
    at org.springframework.webflow.execution.repository.snapshot.SerializedFlowExecutionSnapshot.unmarshal(SerializedFlowExecutionSnapshot.java:101)
    at org.springframework.webflow.execution.repository.snapshot.SerializedFlowExecutionSnapshotFactory.restoreExecution(SerializedFlowExecutionSnapshotFactory.java:80)
    ... 34 more
Caused by: java.io.FileNotFoundException: C:\Users\wombat\.IntelliJIdea12\system\tomcat\Unnamed_workspace_credapp_3\work\Catalina\localhost\Application\upload_57256533_a72f_42e6_97a6_7722c4872b68_00000044.tmp (The system cannot find the file specified)
    at java.io.FileInputStream.open(Native Method)
    at java.io.FileInputStream.<init>(FileInputStream.java:120)
    at org.apache.commons.fileupload.disk.DiskFileItem.readObject(DiskFileItem.java:663)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:969)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1848)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
    at java.util.HashMap.readObject(HashMap.java:1030)
    at sun.reflect.GeneratedMethodAccessor44.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:969)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1848)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
    at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
    at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:479)
    at org.springframework.webflow.core.collection.LocalAttributeMap.readObject(LocalAttributeMap.java:331)
    at sun.reflect.GeneratedMethodAccessor97.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:969)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1848)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
    at org.springframework.webflow.engine.impl.FlowSessionImpl.readExternal(FlowSessionImpl.java:153)
    at java.io.ObjectInputStream.readExternalData(ObjectInputStream.java:1791)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1750)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
    at java.util.LinkedList.readObject(LinkedList.java:964)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:969)
    at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1848)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
    at org.springframework.webflow.engine.impl.FlowExecutionImpl.readExternal(FlowExecutionImpl.java:304)
    at java.io.ObjectInputStream.readExternalData(ObjectInputStream.java:1791)
    at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1750)
    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
    at org.springframework.webflow.execution.repository.snapshot.SerializedFlowExecutionSnapshot.deserialize(SerializedFlowExecutionSnapshot.java:194)
    at org.springframework.webflow.execution.repository.snapshot.SerializedFlowExecutionSnapshot.unmarshal(SerializedFlowExecutionSnapshot.java:99)
    ... 35 more

Answer 1

答案很尷尬，甚至很煩人，很簡單。 如果驗證失敗，則在從驗證返回之前，將表單對象的MultipartFile成員設置為null。

myObject.setFileUpload(null);

當響應發送回客戶端時，Spring將重新創建表單上載控件。

Answer 2

而不是將MultipartFile設置為null：

myObject.setFileUpload(null); （ https://stackoverflow.com/a/22874667/7678594 ）

您可以在類中將屬性聲明為“瞬態”：

private transient CommonsMultipartFile fileUpload;

Answer 3

這些異常在數據綁定時和調用驗證器之前拋出。 可能發生這種情況1）當您上傳的文件超過了配置中multipartresolver bean定義中設置的maxUploadSize並返回到驗證器並訪問了multipartfile時。 2）由於網絡延遲，請求（通過網絡上載）超時。

擴展CommonsMultipartResolver並覆蓋其中的resolveMultipart方法。

    public MultipartHttpServletRequest resolveMultipart(HttpServletRequest request) throws MultipartException {
        String encoding = determineEncoding(request);
        FileUpload fileUpload = prepareFileUpload(encoding);
        try {
        List fileItems = ((ServletFileUpload) fileUpload).parseRequest(request);
        MultipartParsingResult parsingResult = parseFileItems(fileItems, encoding);
        return new DefaultMultipartHttpServletRequest(
                request, parsingResult.getMultipartFiles(), parsingResult.getMultipartParameters(), parsingResult.getMultipartParameterContentTypes());
        } catch (FileUploadBase.SizeLimitExceededException ex) {
            throw new MaxUploadSizeExceededException(fileUpload.getSizeMax(), ex);
        }
        catch (FileUploadException ex) {
            throw new MultipartException("Could not parse multipart servlet request", ex);
        }
    }

如果上傳僅在一個視圖上進行，或者您可以直接定向到錯誤頁面，則使用異常解析器作為：public class YourExceptionResolverextends SimpleMappingExceptionResolver {@Override public ModelAndView resolveException（HttpServletRequest request，HttpServletResponse response，Object handler，Exception exception）{

        if(exception instanceof MaxUploadSizeExceededException) {
        //If (exception instanceof FileUploadBase.SizeLimitExceededException)
            String errorMessage = "ERROR: Filesize exceeded.");
            HashMap<String, Object> model = new HashMap<String, Object>();
            model.put("errorMessage", errorMessage);
            return new ModelAndView("jsp/uploadView", model);
        } else {
            return super.resolveException(request, response, handler, exception); 
        }
    }