import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.File;
import java.net.InetSocketAddress;
import java.net.FileNameMap;
import java.net.URLConnection;
import java.util.concurrent.Executors;

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

public class FileHandler implements HttpHandler {
  FileNameMap fileNameMap = URLConnection.getFileNameMap();
  
  public static void main(String[] args) throws IOException {
      int serverPort = 8080;
      InetSocketAddress addr = new InetSocketAddress(serverPort);
      HttpServer server = HttpServer.create(addr, 0);

      server.createContext("/", new FileHandler());
      server.setExecutor(Executors.newCachedThreadPool());
      server.start();
      System.out.println("Server is listening on port " + serverPort);
  }

  public void handle(HttpExchange exchange) throws IOException {
      String requestMethod = exchange.getRequestMethod();
      String targetPath = exchange.getRequestURI().getPath();
      if (requestMethod.equalsIgnoreCase("GET")) {
          
          // Here it's a good place to include custom path handling,
          // like calls to Java functions
          
          // Handle paths trying to open index.html
          // Instead of this, we could show a list of the files in the folder
          if (targetPath.endsWith("/")) {
              targetPath += "index.html";
          }
          
          // Check if file exists
          File fileFolder = new File(".", "htdocs");
          File targetFile = new File(fileFolder, targetPath.replace('/', File.separatorChar));
          
          if (targetFile.exists() && targetFile.isFile()) {
              // If it exists and it's a file, serve it
              int bufLen = 10000*1024;
              byte[] buf = new byte[bufLen];
              int len    = 0;
              Headers responseHeaders = exchange.getResponseHeaders();
              
              // Get mime type from the ones defined in [jre_home]/lib/content-types.properties 
              String mimeType = fileNameMap.getContentTypeFor(targetFile.toURI().toURL().toString());
              
              if (mimeType == null) {
                  mimeType = "application/octet-stream";
              }
              
              responseHeaders.set("Content-Type", mimeType);
              
              exchange.sendResponseHeaders(200, targetFile.length());
              
              FileInputStream fileIn = new FileInputStream(targetFile);
              OutputStream out = exchange.getResponseBody();
              
              while ((len = fileIn.read(buf,0,bufLen)) != -1) {
                  out.write(buf, 0, len);
              }
              
              out.close();
              fileIn.close();
          } else {
              // If it doesn't exist, send error
              String message = "404 Not Found " + exchange.getRequestURI();
              exchange.sendResponseHeaders(404, 0);
              OutputStream out = exchange.getResponseBody();
              out.write(message.getBytes());
              out.close();
          }
      }
  }
}