Download the image from server side at client side using button in gwt

 


Server Side Code 
package com.server;

import java.io.*;

import java.sql.*;
import java.util.*;
import java.text.*;
import java.util.regex.*;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.*;
import org.mortbay.jetty.Response;

import javax.servlet.*;
import javax.servlet.http.*;

import java.io.*; 
import java.sql.*; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import javax.servlet.ServletInputStream.*; 
import java.io.PrintWriter; 

public class XmlServlet extends HttpServlet { 

public void doPost(HttpServletRequest req,HttpServletResponse res) 
{
    File uploadedFile;

  
    System.out.print("on server");
try{
   
 // String filename =

    File uploadedFile1=new File("./img/"+"happybir.jpg" );

   


  String kk=uploadedFile1.getAbsolutePath();

  System.out.print(kk);

    File f=new File(kk);
 
    //System.out.println("foder is " + folder);
    res.setContentType("application/octet-stream");
    res.setHeader("Content-disposition", "attachment;filename=\"" +"happybir.jpg" + "\"");
    //res.setHeader("Content-Disposition","attachment; filename=;");
    ServletOutputStream stream = res.getOutputStream();
    BufferedInputStream fif = new BufferedInputStream(new FileInputStream(f));
    int data;
    while((data = fif.read()) != -1) {
    stream.write(data);
    }
    fif.close();
    stream.close();
 
}catch(Exception e) 
{ 
System.out.println("Exception Due to"+e); 
e.printStackTrace(); 
} 
} 
}  


Client side

package com.client;

import com.google.gwt.core.client.EntryPoint;

import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.RootPanel;
import com.gwtext.client.widgets.Window;

public class FileDownload  implements EntryPoint {

    public void onModuleLoad() {
    RootPanel rootPanel = RootPanel.get();
    Button clickMeButton = new Button();
    rootPanel.add(clickMeButton);
    clickMeButton.setText("Click me!");
    clickMeButton.addClickHandler(new ClickHandler(){
    public void onClick(ClickEvent event) {
       
        FileUploadWindow window = new FileUploadWindow();
        window.setVisible(true);
    }
    });
   
    }
    }

FileUploadWindow.java

package com.client;


import com.google.gwt.core.client.GWT;

public class FileUploadWindow {

    FormPanel formPanel = new FormPanel();





    public FileUploadWindow() {
       
       
    RootPanel r=RootPanel.get();


    formPanel.setFileUpload(true);
    //setup error reader to process from submit response from server
    RecordDef errorRecordDef = new RecordDef(new FieldDef[]{
    new StringFieldDef("id"),
    new StringFieldDef("msg")
    });
    XmlReader errorReader = new XmlReader("field", errorRecordDef);
    errorReader.setSuccess("@success");
    formPanel.setErrorReader(errorReader);

    //final TextField textField = new TextField("Photo", "file");
    //textField.setInputType("file");
    //textField.setSize("334px", "28px");
    //formPanel.add(textField);


    formPanel.add(new Button("Submit",new ButtonListenerAdapter() {
    public void onClick(Button button, EventObject e) {
    MessageBox.confirm("Confirm", "Do you want to submit?",
    new MessageBox.ConfirmCallback() {
    public void execute(String btnID) {
    if (btnID.equals("yes")) {
    formPanel.getForm().submit(GWT.getModuleBaseURL()+"XmlServlet", null, Connection.GET, "Saving Data...", false);
    }
    }
    });
    }
    }));
    formPanel.addFormListener(new FormListenerAdapter(){
    public boolean doBeforeAction(Form form) {return true;}
    public void onActionComplete(Form form, int httpStatus, java.lang.String responseText){
       
        System.out.println(responseText);
    Image image = new Image("./img/"+"monica.txt");
    image.setSize("300px", "300px");




    }
    public void onActionFailed(Form form, int httpStatus, java.lang.String responseText){
    com.google.gwt.user.client.Window.alert("File upload is failed.");
    }
    });
    r.add(formPanel);
    formPanel.setSize("100px","100px");

    }

    }