Question

When i use one jpeg image with this web-server its very slow to show the picture in the browser. But the same picture when i open using Apache web server its super fast.

What am i missing in my code which is so slow to render the jpeg file? Following is the code i am using:

server.java:

package www;
import java.io.*;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

public class server extends Thread 
{
  public server(int listen_port, webserver_starter to_send_message_to) 
  {
    message_to = to_send_message_to;
    port = listen_port;
    this.start();
  }

  private void s(String s2) 
  { 
    message_to.send_message_to_window(s2);
  }

  private webserver_starter message_to; 
  private int port; 

  public void run() 
  {
    ServerSocket serversocket = null; 
    s("The httpserver v. 0000000000\n\n");

    try {   
      s("Trying to bind to localhost on port " + Integer.toString(port) + "...");      
      serversocket = new ServerSocket(port);
    }catch (Exception e) {
      s("\nFatal Error:" + e.getMessage());

      System.exit(0);
      return;
    }
    s("OK!\n");

    while (true) 
    {
      s("\nReady, Waiting for requests...\n");
      try {
        Socket connectionsocket = serversocket.accept();
        InetAddress client = connectionsocket.getInetAddress();
        s(client.getHostName() + " connected to server.\n");
        BufferedReader input =
            new BufferedReader(new InputStreamReader(connectionsocket.
            getInputStream()));
        DataOutputStream output =
            new DataOutputStream(connectionsocket.getOutputStream());
        http_handler(input, output);
      } catch (Exception e) {         
        s("\nError:" + e.getMessage());
      }

    }
  }

  private void http_handler(BufferedReader input, DataOutputStream output) 
  {
    int method = 0;                   //1 get, 2 head, 0 not supported
    String http = new String();       //a bunch of strings to hold
    String path = new String();       //the various things, what http v, what path,
    String file = new String();       //what file
    String user_agent = new String(); //what user_agent
    try {

      String tmp = input.readLine();  //read from the stream
      String tmp2 = new String(tmp);
      tmp.toUpperCase();              //convert it to uppercase
      if (tmp.startsWith("GET")) {    //compare it is it GET
        method = 1;
      } //if we set it to method 1
      if (tmp.startsWith("HEAD")) {   //same here is it HEAD
        method = 2;
      } //set method to 2

      if (method == 0) { 
        try {
          output.writeBytes(construct_http_header(501, 0));
          output.close();
          return;
        }
        catch (Exception e3) { 
          s("error:" + e3.getMessage());
        }
      }


      int start = 0;
      int end = 0;
      for (int a = 0; a < tmp2.length(); a++) {
        if (tmp2.charAt(a) == ' ' && start != 0) {
          end = a;
          break;
        }
        if (tmp2.charAt(a) == ' ' && start == 0) {
          start = a;
        }
      }
      path = tmp2.substring(start + 2, end);
    }
    catch (Exception e) {
      s("errorr" + e.getMessage());
    } 

    s("\nClient requested:" + new File(path).getAbsolutePath() + "\n");
    FileInputStream requestedfile = null;

    try {
      requestedfile = new FileInputStream(path);
    }
    catch (Exception e) {
      try {
        output.writeBytes(construct_http_header(404, 0));
        output.close();
      }
      catch (Exception e2) {}
      ;
      s("error" + e.getMessage());
    } 


    try {
      int type_is = 0;

      if (path.endsWith(".zip")) 
      {
        type_is = 3;
      }

      if (path.endsWith(".jpg") || path.endsWith(".jpeg")) 
      {
        type_is = 1;
      }

      if (path.endsWith(".gif")) 
      {
        type_is = 2;       
      }

      output.writeBytes(construct_http_header(200, 5));

      if (method == 1) 
      { 
        while (true) 
        {
          int b = requestedfile.read();
          if (b == -1) {
            break; //end of file
          }
          output.write(b);
        }

      }
      output.close();
      requestedfile.close();
    }

    catch (Exception e) {}

  }

  private String construct_http_header(int return_code, int file_type) 
  {
    String s = "HTTP/1.0 ";

    switch (return_code) 
    {
      case 200:
        s = s + "200 OK";
        break;
      case 400:
        s = s + "400 Bad Request";
        break;
      case 403:
        s = s + "403 Forbidden";
        break;
      case 404:
        s = s + "404 Not Found";
        break;
      case 500:
        s = s + "500 Internal Server Error";
        break;
      case 501:
        s = s + "501 Not Implemented";
        break;
    }

    s = s + "\r\n"; 
    s = s + "Connection: close\r\n"; 
    s = s + "Server: SimpleHTTPtutorial v0\r\n";

    switch (file_type) {
      case 0:
        break;
      case 1:
        s = s + "Content-Type: image/jpeg\r\n";
        break;
      case 2:
        s = s + "Content-Type: image/gif\r\n";
      case 3:
        s = s + "Content-Type: application/x-zip-compressed\r\n";
      default:
        //s = s + "Content-Type: text/html\r\n";
        s = s + "Content-Type: image/jpeg\r\n";
        break;
    }
    s = s + "\r\n";
    return s;
  }
}

Answer 1

Well here’s the first thing I’d fix:

while (true) 
{
  int b = requestedfile.read();
  if (b == -1) {
    break; //end of file
  }
  output.write(b);
}

You’re reading and writing a single byte at a time. That will be painfully slow. Read and write a whole buffer at a time instead:

byte[] buffer = new byte[32 * 1024]; // 32K is a reasonable buffer size
int bytesRead;
while ((bytesRead = requestedfile.read(buffer)) > 0) {
    output.write(buffer, 0, bytesRead);
}

There may well be other performance problems in your code – there are certainly a lot of things I’d change about it, including following Java naming conventions everywhere and certainly fixing this:

// You should basically *never* have this code
catch (Exception e){}

… but as you asked about the performance, that’s the first bit I’ve checked for.