java - 在 Spring Web Flow 中上传文件 - 错误处理？

Question

我正在使用 Spring Webflow 和 org.springframework.web.multipart.commons.CommonsMultipartFile从网页上传文件。当输入表单通过验证时，上传工作正常。当表单验证失败并且 Web Flow 尝试重新显示页面时，就会出现问题。它似乎尝试重新加载文件上传控件，它会查找上传使用的临时文件，但它不在那里。看实际MultipartFile.java来源我看到这个评论:

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

因此，应用程序不会重新显示 Web 表单，而是会抛出以下错误。在 Web Flow 内部处理此问题的最佳方法是什么(请记住，Web Flow 不会为您提供与“常规”MVC 相同级别的控制)。我可以扔掉 MultipartFile 对象中的所有内容，但我不知道将其初始化为什么。

这是我现在得到的:

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

这个问题的答案简单得令人尴尬，甚至令人恼火。如果验证失败，请在验证返回之前将表单对象的 MultipartFile 成员设置为 null。

myObject.setFileUpload(null);

当响应发送回客户端时，表单上传控件将由 Spring 重新创建。