I'm trying to write a servlet, that can upload a file from client to server and download a file from server to client from specific location to specific location. But two problems stopped me: 1. When uploading a file from client to server, how to tell to the server where to store the file? 2. (and more important) How to do the downloading from server to client part?
Here is the code so far:
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class Server extends Thread {
public static final int PORT = 3333;
public static final int BUFFER_SIZE = 100;
@Override
public void run() {
try {
ServerSocket serverSocket = new ServerSocket(PORT);
while (true) {
Socket s = serverSocket.accept();
saveFile(s);
}
} catch (Exception e) {
e.printStackTrace();
}
}
private void saveFile(Socket socket) throws Exception {
ObjectOutputStream oos = new ObjectOutputStream(socket.getOutputStream());
ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
FileOutputStream fos = null;
byte [] buffer = new byte[BUFFER_SIZE];
Object o = ois.readObject();
if (o instanceof String) {
fos = new FileOutputStream(o.toString());
} else {
throwException(null);
}
Integer bytesRead = 0;
do {
o = ois.readObject();
if (!(o instanceof Integer)) {
throwException(null);
}
bytesRead = (Integer)o;
o = ois.readObject();
if (!(o instanceof byte[])) {
throwException(null);
}
buffer = (byte[]) o;
fos.write(buffer, 0, bytesRead);
} while (bytesRead == BUFFER_SIZE);
fos.close();
ois.close();
oos.close();
}
public static void throwException(String message) throws Exception {
throw new Exception(message);
}
public static void main(String[] args) {
new Server().start();
}
}
package com.filetransfer.web;
import java.io.*;
import java.net.Socket;
import java.util.Arrays;
import javax.servlet.*;
import javax.servlet.http.*;
public class FileTransfer extends HttpServlet {
private static final long serialVersionUID = 1L;
public static final int PORT = 3333;
public static final int BUFFER_SIZE = 100;
public static final String HOST = "localhost";
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String action = request.getParameter("option");
System.out.println(action);
if ("upload".equals(action)) {
uploadFile(request);
} else if ("download".equals(action)) {
downloadFile(request, response);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
public void reportError(HttpServletResponse response, String message) throws IOException {
response.sendError(HttpServletResponse.SC_NOT_FOUND, message);
}
public void uploadFile(HttpServletRequest request) {
String fileLocation = request.getParameter("localfile");
File file = new File(fileLocation);
Socket socket;
try {
socket = new Socket(HOST, PORT);
ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
ObjectOutputStream oos = new ObjectOutputStream(socket.getOutputStream());
oos.writeObject(file.getName());
FileInputStream fis = new FileInputStream(file);
byte [] buffer = new byte[BUFFER_SIZE];
Integer bytesRead = 0;
while ((bytesRead = fis.read(buffer)) > 0) {
oos.writeObject(bytesRead);
oos.writeObject(Arrays.copyOf(buffer, buffer.length));
}
oos.close();
ois.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public void downloadFile(HttpServletRequest request, HttpServletResponse response) {
File file = new File(request.getParameter("remotefile"));
Socket socket;
InputStream inputStream = null;
OutputStream outputStream = null;
try {
socket = new Socket(HOST, PORT);
response.setContentLength((int)file.length());
outputStream = response.getOutputStream();
inputStream = new BufferedInputStream(new FileInputStream(file));
int nextByte;
while ((nextByte = inputStream.read()) != -1) {
outputStream.write(nextByte);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}