使用Servlet上传文件GWT

Question

I am developing an application with GWT and I'm trying to upload files to the server (or to a directory). I am using a form to submit the chosen file with the FileUpload widget. I have a problem with the servlet that I'm using to upload the files:

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);
        }

}

I get this error :

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

I saw this subject and it says that I should add the commons-fileupload-1.3.jar and commons-io-2.4.jar and I have already done it. How to solve this java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream? Any solution? EDIT: After adding the JARs Directly to my WEB-INF/lib I got this error

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)`

Answer 1

Ensure you have not missed copying the files commons-fileupload-1.3.jar and commons-io-2.4.jar into your WEB-INF/lib. You also should check your launch classpath for devmode.

Example - I have added a sample jar into my lib and can see the same via my launch configuration.

Update - If you are using GAE please read through

1. GWT - image upload and GAE
2. How to upload and store an image with google app engine (java)

Answer 2

A Google App Engine application cannot write to the filesystem .

The DiskFileItemFactory object you use tries to write to the filesystem and therefore you get the following exception:

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

Here's the explanation from DiskFileItemFactory documentation :

This implementation creates FileItem instances which keep their content either in memory, for smaller items, or in a temporary file on disk, for larger items. The size threshold, above which content will be stored on disk, is configurable, as is the directory in which temporary files will be created. If not otherwise configured, the default configuration values are as follows: Size threshold is 10KB.

The solution: You should increase the file size threshold. Override the default. Set it to the largest file size you would like to upload to your servlet.

DiskFileItemFactory factory= new DiskFileItemFactory(5000000,null);

or

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