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Have a simple HTTP serverTag(s): Networking


Since Java 1.6, there's a built-in HTTP server included with the JDK.

The HttpServer provides a simple high-level Http server API, which can be used to build embedded HTTP servers. 

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

/*
 * a simple static http server
*/
public class SimpleHttpServer {

  public static void main(String[] args) throws Exception {
    HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
    server.createContext("/test", new MyHandler());
    server.setExecutor(null); // creates a default executor
    server.start();
  }

  static class MyHandler implements HttpHandler {
    public void handle(HttpExchange t) throws IOException {
      byte [] response = "Welcome Real's HowTo test page".getBytes();
      t.sendResponseHeaders(200, response.length);
      OutputStream os = t.getResponseBody();
      os.write(response);
      os.close();
    }
  }
}
Compile and execute. To access the local server, open a browser at http://localhost:8000/test.

The next HttpServer provides 2 contexts :

  • http://localhost:8000/info to display an informative message.
  • http://localhost:8000/get to download a specific PDF to the browser. 
    import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;
import com.sun.net.httpserver.Headers;

public class SimpleHttpServer {

  public static void main(String[] args) throws Exception {
    HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
    server.createContext("/info", new InfoHandler());
    server.createContext("/get", new GetHandler());
    server.setExecutor(null); // creates a default executor
    server.start();
  }

  static class InfoHandler implements HttpHandler {
    public void handle(HttpExchange t) throws IOException {
      String response = "Use /get to download a PDF";
      t.sendResponseHeaders(200, response.length());
      OutputStream os = t.getResponseBody();
      os.write(response.getBytes());
      os.close();
    }
  }

  static class GetHandler implements HttpHandler {
    public void handle(HttpExchange t) throws IOException {

      // add the required response header for a PDF file
      Headers h = t.getResponseHeaders();
      h.add("Content-Type", "application/pdf");

      // a PDF (you provide your own!)
      File file = new File ("c:/temp/doc.pdf");
      byte [] bytearray  = new byte [(int)file.length()];
      FileInputStream fis = new FileInputStream(file);
      BufferedInputStream bis = new BufferedInputStream(fis);
      bis.read(bytearray, 0, bytearray.length);

      // ok, we are ready to send the response.
      t.sendResponseHeaders(200, file.length());
      OutputStream os = t.getResponseBody();
      os.write(bytearray,0,bytearray.length);
      os.close();
    }
  }
}

    NOTE:
    The packages com.sun.* are not part of the supported, public interface and may even disappear in upcoming Java releases.

    See these related HowTo :

  • Handle URL parameters using the JDK HTTP server
  • Do Basic authentication using the JDK HTTP server
    See also SimpleWeb, an open source http server.