HTTP/1.1 400 Bad Request Received in Java program

[Ravish Srivastava]

Below is my java program, when i m running it it prints "echo: HTTP/1.1 400 Bad Request".

I am taking input from standard input i.e. from keyboard.

    package com.ericsson.examples;
    
    import java.io.DataInputStream;
    import java.io.DataOutputStream;
    import java.io.IOException;
    import java.net.Socket;
    import java.net.UnknownHostException;
    
    public class EchoTest {
    
        public static void main(String[] args) {
            Socket echoSocket = null;
            DataOutputStream os = null;
            DataInputStream is = null;
    	DataInputStream stdIn = new DataInputStream(System.in);
    
            try {
                echoSocket = new Socket("localhost",8081);
                os = new DataOutputStream(echoSocket.getOutputStream());
                is = new DataInputStream(echoSocket.getInputStream());
            } catch (UnknownHostException e) {
                System.err.println("Don't know about host: taranis");
            } catch (IOException e) {
                System.err.println("Couldn't get I/O for the connection to: taranis");
            }
    
            if (echoSocket != null && os != null && is != null) {
                try {
                    String userInput;
    
                    while ((userInput = stdIn.readLine()) != null) {
                    	
                        os.writeBytes(userInput);
                        os.writeByte('\r');
                        os.writeByte('\n');
                        System.out.println("echo: " + is.readLine());
                    }
                    os.close();
                    is.close();
                    echoSocket.close();
                } catch (IOException e) {
                    System.err.println("I/O failed on the connection to: taranis");
                }
            }
        }
    }

[Ulf Dittmer]

What doss the client actually send? What kind of server process is it communicating with?

[Jesper de Jong]

It looks like you are connecting to a HTTP server with your program. You're sending data to the HTTP server that doesn't look like a HTTP request, so the server complains about that with a "400 Bad Request" error message.

Why are you connecting to a HTTP server? A HTTP server does not work like an echo server, which seems to be what this program expects.