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Asked: 2026-05-30T04:34:03+00:00

I wrote this HttpRequest method, but for some reason it always goes to 404

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I wrote this HttpRequest method, but for some reason it always goes to 404 Not Found, even though the file location exists when the java process isn’t running.

import java.io.*;
import java.net.*;
import java.util.*;

final class HttpRequest implements Runnable {
    final static String CRLF = "\r\n";
    Socket socket;

    // Constructor
    public HttpRequest(Socket socket) throws Exception {
        this.socket = socket;
    }

    // Implement the run() method of the Runnable interface.
    public void run() {
        try {
            processRequest();
        } catch (Exception e) {
            System.out.println(e);
        }
    }

    private static void sendBytes(FileInputStream fis, OutputStream os) 
    throws Exception {
    // Construct a 1K buffer to hold bytes on their way to the socket.
    byte[] buffer = new byte[1024];
    int bytes = 0;

    // Copy requested file into the socket's output stream.
    while((bytes = fis.read(buffer)) != -1 ) {
        os.write(buffer, 0, bytes);
        }
    }

    private static String contentType(String fileName) {
    if(fileName.endsWith(".htm") || fileName.endsWith(".html")) {
        return "text/html";
    }
    if(fileName.endsWith(".jpeg") || fileName.endsWith(".jpg")) {
    return "image/jpeg";
    }
    if(fileName.endsWith(".gif")) {
    return "image/gif";
    }
    return "application/octet-stream";
    }

    private void processRequest() throws Exception {
        // Get a reference to the socket's input and output streams.
        InputStream is = socket.getInputStream();
        DataOutputStream os = new DataOutputStream(socket.getOutputStream());

        // Set up input stream filters.
        BufferedReader br = new BufferedReader(new InputStreamReader(is));

        // Get the request line of the HTTP request message.
        String requestLine = new String(br.readLine());

        // Display the request line.
        System.out.println();
        System.out.println(requestLine);

        // Get and display the header lines.
        String headerLine = null;
        while ((headerLine = br.readLine()).length() != 0) {
            System.out.println(headerLine);
        }

    // Extract the filename from the request line.
    StringTokenizer tokens = new StringTokenizer(requestLine);
    tokens.nextToken(); // skip over the method, which should be "GET"
    String fileName = tokens.nextToken();
    // Prepend a "." so that file request is within the current directory.
    fileName = "." + fileName;

    // Open the requested file.
    FileInputStream fis = null;
    boolean fileExists = true;
    try {
    fis = new FileInputStream(fileName);
    } catch (FileNotFoundException e) {
    fileExists = false;
    }

    // Construct the response message.
    String statusLine = null;
    String contentTypeLine = null;
    String entityBody = null;
    if (fileExists) {
    statusLine = "200 OK" + CRLF;
    contentTypeLine = "Content-type: " + 
        contentType( fileName ) + CRLF;
    } else {
    statusLine = "404 NOT FOUND" + CRLF;
    contentTypeLine = "Content Not Found!" + CRLF;
    entityBody = "<HTML>" + 
        "<HEAD><TITLE>Not Found</TITLE></HEAD>" +
        "<BODY>Not Found</BODY></HTML>";
    }

    // Send the status line.
    os.writeBytes(statusLine);

    // Send the content type line.
    os.writeBytes(contentTypeLine);

    // Send a blank line to indicate the end of the header lines.
    os.writeBytes(CRLF);

    // Send the entity body.
    if (fileExists) {
    sendBytes(fis, os);
    fis.close();
    } else {
    os.writeBytes("File DNE: Content Not Found!");
    }

        // Close streams and socket.
        os.close();
        br.close();
        socket.close();
    }
}

Any help would be greatly appreciated…I feel like it’s something simple I’m missing.

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1 Answer

  1. Editorial Team

    I ran your code; it works fine (except for some minor issues with not printing the headers correctly, which every browser I’ve tried is willing to completely ignore).

    Are you sure your working directory is where you expect? Try changing the 404 message to something like:

    contentTypeLine = "Content Not Found: " + new File(fileName).getAbsolutePath() + CRLF;

    For reference, I ran it with a test harness of:

    public static void main(String[] args) throws Exception {
        final ServerSocket ss = new ServerSocket(8080);
        while (true)
            new HttpRequest(ss.accept()).run();
    }
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