使用servlet上传文件GWT

我正在开发一个应用程序与GWT，我试图上传文件到服务器（或目录）。我正在使用表单将所选文件与FileUpload小部件一起提交。我有我使用上传文件的servlet的一个问题：使用servlet上传文件GWT

package com.asso.server; 

import java.io.File; 
import java.io.IOException; 
import java.util.List; 

import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

import org.apache.commons.fileupload.FileItem; 
import org.apache.commons.fileupload.FileItemFactory; 
import org.apache.commons.fileupload.disk.DiskFileItemFactory; 
import org.apache.commons.fileupload.servlet.ServletFileUpload; 
import org.apache.commons.io.FilenameUtils; 

/** 
* servlet to handle file upload requests 
* 
* @author hturksoy 
* 
*/ 
public class FileUploadServlet extends HttpServlet { 

     private static final String UPLOAD_DIRECTORY = "c:\\uploaded\\"; 
     private static final String DEFAULT_TEMP_DIR = "."; 

     @Override 
     protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
         throws ServletException, IOException { 
       // TODO Auto-generated method stub 
       super.doGet(req, resp); 
     } 

     @Override 
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) 
         throws ServletException, IOException { 

       // process only multipart requests 
       if (ServletFileUpload.isMultipartContent(req)) { 

         File tempDir = getTempDir(); 
         if (!tempDir.exists()) { 
           tempDir.mkdirs(); 
         } 

         // Create a factory for disk-based file items 
         FileItemFactory factory = new DiskFileItemFactory(); 

         // Create a new file upload handler 
         ServletFileUpload upload = new ServletFileUpload(factory); 

         // Parse the request 
         try { 
           List<FileItem> items = upload.parseRequest(req); 
           for (FileItem fileItem : items) { 
             // process only file upload 
             if (fileItem.isFormField()) continue; 

             String fileName = fileItem.getName(); 
             // get only the file name not whole path 
             if (fileName != null) { 
             fileName = FilenameUtils. getName(fileName); 
            } 

             File uploadedFile = new File(UPLOAD_DIRECTORY, fileName); 
             if (uploadedFile.createNewFile()) { 
               fileItem.write(uploadedFile); 
               resp.setStatus(HttpServletResponse.SC_CREATED); 
               resp.getWriter().print("The file was created successfully."); 
               resp.flushBuffer(); 
             } else 
               throw new IOException("The file already exists in repository."); 
           } 
         } catch (Exception e) { 
           resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, 
               "An error occurred while creating the file : " + e.getMessage()); 
         } 

       } else { 
         resp.sendError(HttpServletResponse.SC_UNSUPPORTED_MEDIA_TYPE, 
                 "Request contents type is not supported by the servlet."); 
       } 
     } 

     private File getTempDir() { 
       return new File(DEFAULT_TEMP_DIR); 
     } 

}

我得到这个错误：

java.lang.NoClassDefFoundError: org/apache/commons/fileupload/FileItemFactory 
    at java.lang.Class.getDeclaredConstructors0(Native Method) 
    at java.lang.Class.privateGetDeclaredConstructors(Unknown Source) 
    at java.lang.Class.getConstructor0(Unknown Source) 
    at java.lang.Class.newInstance0(Unknown Source) 
    at java.lang.Class.newInstance(Unknown Source) 
    at org.mortbay.jetty.servlet.Holder.newInstance(Holder.java:153) 
    at org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:428) 
    at org.mortbay.jetty.servlet.ServletHolder.getServlet(ServletHolder.java:339) 
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) 
    at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:123) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:61) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.DevAppServerServersFilter.doFilter(DevAppServerServersFilter.java:106) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) 
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) 
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) 
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) 
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) 
    at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:94) 
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:421) 
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
    at org.mortbay.jetty.Server.handle(Server.java:326) 
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) 
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938) 
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755) 
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218) 
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) 
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409) 
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582) 
Caused by: java.lang.ClassNotFoundException: org.apache.commons.fileupload.FileItemFactory 
    at java.net.URLClassLoader$1.run(Unknown Source) 
    at java.net.URLClassLoader$1.run(Unknown Source) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.net.URLClassLoader.findClass(Unknown Source) 
    at java.lang.ClassLoader.loadClass(Unknown Source) 
    at com.google.appengine.tools.development.IsolatedAppClassLoader.loadClass(IsolatedAppClassLoader.java:214) 
    at java.lang.ClassLoader.loadClass(Unknown Source) 
    ... 41 more

我看到了这个问题，它说，我要补充的commons-fileupload-1.3.jar和commons-io-2.4.jar我已经完成了。 How to solve this java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream? 任何解决方案？编辑：直接添加JAR文件到我的WEB-INF/lib目录后，我得到这个错误

java.lang.NoClassDefFoundError: `java.io.FileOutputStream is a restricted class. Please see the Google App Engine developer's guide for more details. 
    at com.google.appengine.tools.development.agent.runtime.Runtime.reject(Runtime.java:51) 
    at org.apache.commons.io.output.DeferredFileOutputStream.thresholdReached(DeferredFileOutputStream.java:178) 
    at org.apache.commons.io.output.ThresholdingOutputStream.checkThreshold(ThresholdingOutputStream.java:224) 
    at org.apache.commons.io.output.ThresholdingOutputStream.write(ThresholdingOutputStream.java:128) 
    at org.apache.commons.fileupload.util.Streams.copy(Streams.java:108) 
    at org.apache.commons.fileupload.util.Streams.copy(Streams.java:70) 
    at org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:347) 
    at org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:115) 
    at com.asso.server.FileUploadServlet.doPost(FileUploadServlet.java:56) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) 
    at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:123) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:61) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.DevAppServerServersFilter.doFilter(DevAppServerServersFilter.java:106) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) 
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) 
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) 
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) 
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) 
    at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:94) 
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:421) 
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
    at org.mortbay.jetty.Server.handle(Server.java:326) 
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) 
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938) 
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755) 
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218) 
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) 
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409) 
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)`

来源

2013-04-17 Hassen Ch.

你重新启动服务器？（关闭开发模式，并重新启动不重启按钮） – David

是的，我做了很多次！ –

您是使用maven还是将apache jar复制到WEB-INF/lib中？是Dev模式还是Prod模式下的错误？ – SSR

确保你没有错过复制文件的commons-文件上传-1.3.jar和commons-IO-2.4.jar到您的WEB-INF/lib中。你也应该检查你的启动类路径的devmode。

示例 - 我已经添加了一个样本jar到我的lib中，并可以通过我的启动配置看到相同的结果。

更新 - 如果你正在使用GAE请通读

enter image description here

来源

2013-04-18 03:36:37 SSR

我没有将它们复制到WEB-INF/lib，我将它们添加为外部JAR。但我有他们在我的建立路径和类路径 –

看看编辑和新的错误 –

避免张贴更新作为答案！由于您试图使用谷歌应用程序引擎您的查询可能会通过http://stackoverflow.com/questions/1513603/how-to-upload-and-store-an-image-with-google-app-engine-java – SSR

Google App Engine应用程序cannot write to the filesystem。

您使用试图写入文件系统，因此你会得到以下异常的DiskFileItemFactory对象：

java.lang.NoClassDefFoundError: `java.io.FileOutputStream is a restricted class. Please see the Google App Engine developer's guide for more details.

下面是DiskFileItemFactory documentation的解释：

此实现创建其保持的FileItem情况下，它们无论是在内存中，对于较小的项目，还是在磁盘上的临时文件中，对于较大的项目。大小阈值（高于该阈值的内容将被存储在磁盘上）是可配置的，因为将创建临时文件的目录。如果没有另外配置，则的默认配置值如下所示：大小阈值为10KB。

解决方案：您应该增加文件大小阈值。覆盖默认值。将其设置为您想要上传到您的servlet的最大文件大小。

DiskFileItemFactory factory= new DiskFileItemFactory(5000000,null);

或

DiskFileItemFactory factory= new DiskFileItemFactory(); 
factory.setSizeThreshold(5000000);

来源

2013-08-10 15:36:35

使用servlet上传文件GWT

回答

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