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POhow to let Java HttpServer handle Post Request for File Upload
 

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  1. POhow to let Java HttpServer handle Post Request for File Upload
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    <p>First of all, my question is about HttpServer in Java to handle the POST request from a client, <strong>not</strong> about a Java client who can upload file to a web server.</p> <p>OK. I am using a lightweight HttpServer in Java to handle "GET" || "POST" requests. The source code of the HttpServer is copied from <a href="http://www.prasannatech.net/2008/11/http-web-server-java-post-file-upload.html" rel="nofollow">http://www.prasannatech.net/2008/11/http-web-server-java-post-file-upload.html</a>.</p> <pre><code>/* * HTTPPOSTServer.java * Author: S.Prasanna * @version 1.00 */ import java.io.*; import java.net.*; import java.util.*; public class HTTPPOSTServer extends Thread { static final String HTML_START = "&lt;html&gt;" + "&lt;title&gt;HTTP POST Server in java&lt;/title&gt;" + "&lt;body&gt;"; static final String HTML_END = "&lt;/body&gt;" + "&lt;/html&gt;"; Socket connectedClient = null; BufferedReader inFromClient = null; DataOutputStream outToClient = null; public HTTPPOSTServer(Socket client) { connectedClient = client; } public void run() { String currentLine = null, postBoundary = null, contentength = null, filename = null, contentLength = null; PrintWriter fout = null; try { System.out.println( "The Client "+ connectedClient.getInetAddress() + ":" + connectedClient.getPort() + " is connected"); inFromClient = new BufferedReader(new InputStreamReader (connectedClient.getInputStream())); outToClient = new DataOutputStream(connectedClient.getOutputStream()); currentLine = inFromClient.readLine(); String headerLine = currentLine; StringTokenizer tokenizer = new StringTokenizer(headerLine); String httpMethod = tokenizer.nextToken(); String httpQueryString = tokenizer.nextToken(); System.out.println(currentLine); if (httpMethod.equals("GET")) { System.out.println("GET request"); if (httpQueryString.equals("/")) { // The default home page String responseString = HTTPPOSTServer.HTML_START + "&lt;form action=\"http://127.0.0.1:5000\" enctype=\"multipart/form-data\"" + "method=\"post\"&gt;" + "Enter the name of the File &lt;input name=\"file\" type=\"file\"&gt;&lt;br&gt;" + "&lt;input value=\"Upload\" type=\"submit\"&gt;&lt;/form&gt;" + "Upload only text files." + HTTPPOSTServer.HTML_END; sendResponse(200, responseString , false); } else { sendResponse(404, "&lt;b&gt;The Requested resource not found ...." + "Usage: http://127.0.0.1:5000&lt;/b&gt;", false); } } else { //POST request System.out.println("POST request"); do { currentLine = inFromClient.readLine(); if (currentLine.indexOf("Content-Type: multipart/form-data") != -1) { String boundary = currentLine.split("boundary=")[1]; // The POST boundary while (true) { currentLine = inFromClient.readLine(); if (currentLine.indexOf("Content-Length:") != -1) { contentLength = currentLine.split(" ")[1]; System.out.println("Content Length = " + contentLength); break; } } //Content length should be &lt; 2MB if (Long.valueOf(contentLength) &gt; 2000000L) { sendResponse(200, "File size should be &lt; 2MB", false); } while (true) { currentLine = inFromClient.readLine(); if (currentLine.indexOf("--" + boundary) != -1) { filename = inFromClient.readLine().split("filename=")[1].replaceAll("\"", ""); String [] filelist = filename.split("\\" + System.getProperty("file.separator")); filename = filelist[filelist.length - 1]; System.out.println("File to be uploaded = " + filename); break; } } String fileContentType = inFromClient.readLine().split(" ")[1]; System.out.println("File content type = " + fileContentType); inFromClient.readLine(); //assert(inFromClient.readLine().equals("")) : "Expected line in POST request is "" "; fout = new PrintWriter(filename); String prevLine = inFromClient.readLine(); currentLine = inFromClient.readLine(); //Here we upload the actual file contents while (true) { if (currentLine.equals("--" + boundary + "--")) { fout.print(prevLine); break; } else { fout.println(prevLine); } prevLine = currentLine; currentLine = inFromClient.readLine(); } sendResponse(200, "File " + filename + " Uploaded..", false); fout.close(); } //if }while (inFromClient.ready()); //End of do-while }//else } catch (Exception e) { e.printStackTrace(); } } public void sendResponse (int statusCode, String responseString, boolean isFile) throws Exception { String statusLine = null; String serverdetails = "Server: Java HTTPServer"; String contentLengthLine = null; String fileName = null; String contentTypeLine = "Content-Type: text/html" + "\r\n"; FileInputStream fin = null; if (statusCode == 200) statusLine = "HTTP/1.1 200 OK" + "\r\n"; else statusLine = "HTTP/1.1 404 Not Found" + "\r\n"; if (isFile) { fileName = responseString; fin = new FileInputStream(fileName); contentLengthLine = "Content-Length: " + Integer.toString(fin.available()) + "\r\n"; if (!fileName.endsWith(".htm") &amp;&amp; !fileName.endsWith(".html")) contentTypeLine = "Content-Type: \r\n"; } else { responseString = HTTPPOSTServer.HTML_START + responseString + HTTPPOSTServer.HTML_END; contentLengthLine = "Content-Length: " + responseString.length() + "\r\n"; } outToClient.writeBytes(statusLine); outToClient.writeBytes(serverdetails); outToClient.writeBytes(contentTypeLine); outToClient.writeBytes(contentLengthLine); outToClient.writeBytes("Connection: close\r\n"); outToClient.writeBytes("\r\n"); if (isFile) sendFile(fin, outToClient); else outToClient.writeBytes(responseString); outToClient.close(); } public void sendFile (FileInputStream fin, DataOutputStream out) throws Exception { byte[] buffer = new byte[1024] ; int bytesRead; while ((bytesRead = fin.read(buffer)) != -1 ) { out.write(buffer, 0, bytesRead); } fin.close(); } public static void main (String args[]) throws Exception { ServerSocket Server = new ServerSocket (5000); System.out.println ("HTTP Server Waiting for client on port 5000"); while(true) { Socket connected = Server.accept(); (new HTTPPOSTServer(connected)).start(); } } } </code></pre> <p>I read through the code, I think the code should be all right. </p> <p>But when I try to upload a file, it will print out POST request, and then hang there and never receive any bytes.</p> <p>If you are willing to, you can run the above source code directly. After launch it, you can type 127.0.0.1:5000 in a browser, and it will show a file upload, then if I try upload a file, it will hang there after printing PoST request.</p> <p>If you are bored to read the code, may I ask the following simpler question?</p> <p>So, what exactly Chrome or any other web browser do about form -> input type='file'?</p> <p>If I am using a ServerSocket to handle the HTTP request, I just get the InputStream of the request, and then all the content (including HTTP headers &amp; the uploading file's content) will go through that InputStream, right?</p> <p>The above code can analyse the headers, but then it seems nothing is sent from the browser any more.</p> <p>Can anyone pls help?</p> <p>Thanks</p>
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