package com.ivanov_void.fileupload.client;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import com.extjs.gxt.ui.client.Style.HorizontalAlignment;
import com.extjs.gxt.ui.client.data.BaseModel;
import com.extjs.gxt.ui.client.event.ButtonEvent;
import com.extjs.gxt.ui.client.event.ComponentEvent;
import com.extjs.gxt.ui.client.event.SelectionListener;
import com.extjs.gxt.ui.client.store.ListStore;
import com.extjs.gxt.ui.client.widget.LayoutContainer;
import com.extjs.gxt.ui.client.widget.MessageBox;
import com.extjs.gxt.ui.client.widget.VerticalPanel;
import com.extjs.gxt.ui.client.widget.button.Button;
import com.extjs.gxt.ui.client.widget.form.ComboBox;
import com.extjs.gxt.ui.client.widget.form.FileUploadField;
import com.extjs.gxt.ui.client.widget.form.FormPanel;
import com.extjs.gxt.ui.client.widget.form.TextField;
import com.extjs.gxt.ui.client.widget.form.ComboBox.TriggerAction;
import com.extjs.gxt.ui.client.widget.form.FormPanel.Encoding;
import com.extjs.gxt.ui.client.widget.form.FormPanel.Method;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.user.client.Element;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.FileUpload;
import com.google.gwt.user.client.ui.FormHandler;
import com.google.gwt.user.client.ui.FormSubmitCompleteEvent;
import com.google.gwt.user.client.ui.FormSubmitEvent;
import com.google.gwt.user.client.ui.RootPanel;

public class FileUploadApplication implements EntryPoint {
  public void onModuleLoad() {
	  final FormPanel form = new FormPanel();
      form.setAction("fileupload");
      form.setEncoding(Encoding.MULTIPART);
      form.setMethod(Method.POST);
      
      // Create a FileUpload widget.
      FileUpload upload = new FileUpload();
      upload.setName("uploadFormElement");
      
      form.add(upload);
      
      Button btn = new Button("Submit");
      btn.addSelectionListener(new SelectionListener<ButtonEvent>() {
    
      @Override
      public void componentSelected(ButtonEvent ce) {
        if (!form.isValid()) {
          return;
        }
        
        form.submit();        
        MessageBox.info("Action", "You file was uploaded", null);
      }
    });
    form.addButton(btn);           
    RootPanel.get().add(form);
  }
}

package com.ivanov_void.fileupload.server;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;
 
import javax.servlet.ServletConfig;
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.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
 
/**
 *  
 * @author ivanov-void
 *
 */
public class MyFormHandler extends HttpServlet {
	//
	private static final String TEMP_DIR = "c:\\tmp";
	//
	private File tmpDir;
	//
	private static final String DESTINATION_DIR_PATH ="/files";
	//
	private File destinationDir;
	/**
	 * init servlet in lifecycle
	 * 
	 */
	public void init(ServletConfig config) 
			throws ServletException {
		super.init(config);
		
		tmpDir = new File(TEMP_DIR);
		if(!tmpDir.isDirectory()) throw new ServletException(
				TEMP_DIR + " is not a directory");
		
		String realPath = getServletContext().
			getRealPath(DESTINATION_DIR_PATH);
		
		destinationDir = new File(realPath);
		if(!destinationDir.isDirectory()) 
			throw new ServletException(
					DESTINATION_DIR_PATH+" is not a directory");		
	}
	/**
	 * file upload processing
	 * 
	 */
	protected void doPost(HttpServletRequest request, 
			HttpServletResponse response) 
				throws ServletException, IOException {
	    PrintWriter out = response.getWriter();
	    // conf
	    response.setContentType("text/plain");
 
		DiskFileItemFactory  fileItemFactory = new DiskFileItemFactory ();
		// Set the size threshold, above which content will be stored on disk.
		fileItemFactory.setSizeThreshold(1*1024*1024); //1 MB
		// Set the temporary directory to store the uploaded files of size above threshold.
		fileItemFactory.setRepository(tmpDir);
 
		ServletFileUpload uploadHandler = 
			new ServletFileUpload(fileItemFactory);
		try {
			// Parse the request
			List items = uploadHandler.parseRequest(request);
			Iterator itr = items.iterator();
			while(itr.hasNext()) {
				FileItem item = (FileItem) itr.next();

				// Handle Form Fields.
				if(item.isFormField()) {
					out.println("File Name = "+item.getFieldName()+", " +
							"Value = "+item.getString());
				} else {
					//Handle Uploaded files.
					out.println("Field Name = "+item.getFieldName()+
						", File Name = "+item.getName()+
						", Content type = "+item.getContentType()+
						", File Size = "+item.getSize());

					//Write file to the ultimate location.
					File file = new File(destinationDir,item.getName());
					item.write(file);
				}
				out.close();
			}
		}catch(FileUploadException ex) {
			log("Error encountered while parsing the request",ex);
		} catch(Exception ex) {
			log("Error encountered while uploading file",ex);
		}
	}
}

package com.ivanov_void.fileupload.shared;

/**
 * <p>
 * FieldVerifier validates that the name the user enters is valid.
 * </p>
 * <p>
 * This class is in the <code>shared</code> package because we use it in both
 * the client code and on the server. On the client, we verify that the name is
 * valid before sending an RPC request so the user doesn't have to wait for a
 * network round trip to get feedback. On the server, we verify that the name is
 * correct to ensure that the input is correct regardless of where the RPC
 * originates.
 * </p>
 * <p>
 * When creating a class that is used on both the client and the server, be sure
 * that all code is translatable and does not use native JavaScript. Code that
 * is not translatable (such as code that interacts with a database or the file
 * system) cannot be compiled into client side JavaScript. Code that uses native
 * JavaScript (such as Widgets) cannot be run on the server.
 * </p>
 */
public class FieldVerifier {

	/**
	 * Verifies that the specified name is valid for our service.
	 * 
	 * In this example, we only require that the name is at least four
	 * characters. In your application, you can use more complex checks to ensure
	 * that usernames, passwords, email addresses, URLs, and other fields have the
	 * proper syntax.
	 * 
	 * @param name the name to validate
	 * @return true if valid, false if invalid
	 */
	public static boolean isValidName(String name) {
		if (name == null) {
			return false;
		}
		return name.length() > 3;
	}
}

<?xml version="1.0" encoding="UTF-8"?>
<module rename-to='fileuploadapplication'>

  <inherits name='com.google.gwt.user.User'/>
  <inherits name='com.extjs.gxt.ui.GXT'/>  

  <inherits name='com.google.gwt.user.theme.clean.Clean'/>

  <!-- Specify the app entry point class.                         -->
  <entry-point class='com.ivanov_void.fileupload.client.FileUploadApplication'/>

  <!-- Specify the paths for translatable code                    -->
  <source path='client'/>
  <source path='shared'/>

  <!-- Specify handler class.                         -->
  <servlet class='com.ivanov_void.fileupload.server.MyFormHandler' path='/fileupload'/>

</module>

<?xml version="1.0" encoding="UTF-8" standalone="no"?><web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.5" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee                http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

  <!-- Servlets &mappings -->

  <servlet>
    <servlet-name>MyFormHandler</servlet-name>
    <servlet-class>com.ivanov_void.fileupload.server.MyFormHandler</servlet-class>
  </servlet>

  <servlet-mapping>
  	<servlet-name>MyFormHandler</servlet-name>
  	<url-pattern>/fileupload</url-pattern>
  </servlet-mapping>
  
  <!-- Default page to serve -->
  <welcome-file-list>
    <welcome-file>FileUploadApplication.html</welcome-file>
  </welcome-file-list>

  <servlet>
    <servlet-name>SystemServiceServlet</servlet-name>
    <servlet-class>com.google.api.server.spi.SystemServiceServlet</servlet-class>
    <init-param>
      <param-name>services</param-name>
      <param-value/>
    </init-param>
  </servlet>
  
  <servlet-mapping>
    <servlet-name>SystemServiceServlet</servlet-name>
    <url-pattern>/_ah/spi/*</url-pattern>
  </servlet-mapping>

</web-app>