kebaAgent/src/kebaagent/Webserver.java

/*
 */
package kebaagent;

import com.sun.net.httpserver.Headers;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpHandlers;
import com.sun.net.httpserver.HttpServer;
import com.sun.net.httpserver.Request;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.util.Optional;
import java.util.function.Predicate;


/**
 *
 * @author holz
 */
public class Webserver
{

	private final int port;

	private KebaAgent agent;
	
/**
 * call start()
 * @see #start() 
 * @param port 
 */	
	public Webserver(int port)
	{
		this.port = port;
	}

	
/**
 * Start Webserver
 * @param agent
 * @throws IOException 
 */	
	public void start(KebaAgent agent) throws IOException
	{
		this.agent = agent;
		
// Create an HttpServer instance on port 
		HttpServer server = HttpServer.create(new InetSocketAddress(port), 0);
		
		String defaultUri = "/keba";
		Optional<String> pv = agent.getPropValue("webserver", "defaultUri");
		if (pv.isPresent())
			defaultUri = pv.get();
		
// Define a context that serves files from the current directory
//        server.createContext("/", new com.sun.net.httpserver.HttpHandler() 
//		{
//            @Override
//            public void handle(com.sun.net.httpserver.HttpExchange exchange) throws IOException 
//			{
//                // Handle requests here (simple file serving)
//				System.out.println("recvd: " + exchange);
//// TODO: müsste jetzt die Response generieren. Wie genau, noch nicht nachvollzogen
		//// ein komplexeres Bsp unter https://dzone.com/articles/simple-http-server-in-java
		//// Daraus stammt die Klasse MyHttpHandler unten
//            }
//        });


// andere Variante für Handler am Bsp url http://localhost:8000/t/allowed oder http://localhost:8000/t<irgendwas anderes>
//		Headers headers = new Headers();
//		headers.set("Allow", "GET");
//		headers.set("Content-Type", "text/plain");
//		
//		HttpHandler allowedResponse = HttpHandlers.of(200, headers, getBody());		// Statuscode, Headers, body

// Trivialhandler für einfache Antwort
		HttpHandler deniedResponse = HttpHandlers.of(401, Headers.of("Deny", "GET"), "Denied");
		
		JsonHandler allowedResponse = new JsonHandler(agent);
		
		
// welche URL ist erlaubt?
		final String fDefUri = defaultUri;
		Predicate<Request> findAllowedPath = r -> 
//			r.getRequestURI().getPath().equals("/t/allowed");
			r.getRequestURI().getPath().equals(fDefUri);

		HttpHandler handler = HttpHandlers.handleOrElse(findAllowedPath, allowedResponse, deniedResponse);
// context ist weiter oben angebunden (ab /t)
//		server.createContext("/t", handler); 
		server.createContext(defaultUri, handler); 

// ggf. 2. Handler für / bauen (Infoseite)

		
// mit MyHttpHandler, ziemlich buggy und unvollständig von https://dzone.com/articles/simple-http-server-in-java 
//		MyHttpHandler myHandler = new MyHttpHandler(agent);
//		server.createContext("/m", myHandler);
		
		
        // Start the server
        server.start();
        System.out.printf("Server started on port %d\n", port);

		
	}

	
//	private String getBody()
//	{
//		return "{ 'info': 'hello'}";
//	}
//	
	
	
	
private static class MyHttpHandler implements HttpHandler 
{    

	private KebaAgent agent;
	
		private MyHttpHandler(KebaAgent a)
		{
			agent = a;
		}

/**
 * zu implementierende Methode
 * @param httpExchange
 * @throws IOException 
 */	
  @Override    
  public void handle(HttpExchange httpExchange) throws IOException 
  {
		String requestParamValue = null; 
		System.out.println("MyHttpHandler.handle() httpExchange " + httpExchange);
		String requestMethod = httpExchange.getRequestMethod();
		System.out.println("MyHttpHandler.handle().getRequestMethod(): " + requestMethod);
		if ("GET".equals(httpExchange.getRequestMethod())) 
		{ 
		   requestParamValue = handleGetRequest(httpExchange);
		   System.out.println("MyHttpHandler.handle() GET: requestParamValue = " + requestParamValue);
		}
// TODO: nicht im Bsp.
//	else if("POST".equals(httpExchange)) 
//	{ 
//       requestParamValue = handlePostRequest(httpExchange);        
//    }  
    handleResponse(httpExchange, requestParamValue); 
  }

  
  
/**
 * hier hat der Autor Schwachsinn produziert
 * @param httpExchange
 * @return 
 */  
  private String handleGetRequest(HttpExchange httpExchange) 
  {
		String path = httpExchange.getRequestURI().toString();

		try
		{
//			return path.split("\\?")[1]
			return path.split("/")[1]
//                    .split("=")[1];
			;
		} catch (Exception e)
		{
			e.printStackTrace();
			return e.getMessage();
		}
   }

  
  
   private void handleResponse(HttpExchange httpExchange, String requestParamValue) throws  IOException 
   {
		System.out.println("MyHttpHandler.handleResponse ");
		OutputStream outputStream = httpExchange.getResponseBody();
		StringBuilder htmlBuilder = new StringBuilder();
		htmlBuilder
				.append("<html>")
				.append("<body>")
				.append("<h1>")
				.append("Hello ")
				.append(requestParamValue)
				.append("</h1>")
				.append("</body>")
				.append("</html>");
            // encode HTML content 
// apache commons text + lang
			try
			{
// Schwachsinn: Anwendung auf den ganzen HTML-Code
//				String htmlResponse = StringEscapeUtils.escapeHtml4(htmlBuilder.toString());
// So OK
				String htmlResponse = htmlBuilder.toString();
				
// jaho: Header erweitern
				Headers responseHeaders = httpExchange.getResponseHeaders();
				responseHeaders.set("Content-Type", "text/plain");


// this line is a must (jaho: header senden)
				httpExchange.sendResponseHeaders(200, htmlResponse.length());
				
				
				outputStream.write(htmlResponse.getBytes());
				outputStream.flush();
				outputStream.close();
		   
			} catch (Throwable e)
			{
				e.printStackTrace();
			}


        }
   
} // MyHttpHandler
	
	
	
}