Java HttpServer Example

In this example we are going to learn hpw to run HttpServer on local machine

com.sun.net.httpserver provides Http Server API which can be used to build HTTP Server
Before going to start check below classes

HttpServer
This is a class which implements HTTP Server. This calss as method create() to create instance of the class.
We need to bind the server to an IP Address and a Port number while initializing.

HttpContext
Class which represents a mapping between root URI path to a httpHandler.

HttpHandler
Interface which needs to be implemented by the application to handle the Http request

HttpExchange
The Instance of this class is passed to HttpHandler class method handle(). This method will handle the input request and prepare and send output response.Let's check the code

public class BasicHttpServerExample {

public static void main(String[] args) throws IOException {
HttpServer server = HttpServer.create(new InetSocketAddress(8001), 0);
HttpContext context = server.createContext("/");
context.setHandler(BasicHttpServerExample::handleRequest);
server.start();
}

private static void handleRequest(HttpExchange exchange) throws IOException {
String response = "Welcome from Server!";
exchange.sendResponseHeaders(200, response.getBytes().length);//response code and length
OutputStream os = exchange.getResponseBody();
os.write(response.getBytes());
os.close();
}
}

Output

Java HttpServer

Accessing Request Information

public class HttpServerApp {

/**
* @param args the command line arguments
*/
public static void main(String[] args) {
try {
HttpServer server = HttpServer.create(new InetSocketAddress("localhost", 8001), 0);
server.createContext("/test", new MyHttpHandler());
ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor)Executors.newFixedThreadPool(10);
server.setExecutor(threadPoolExecutor);

server.start();

Logger.getLogger(" Server started on port 8001");
} catch (IOException ex) {
Logger.getLogger(HttpServerApp.class.getName()).log(Level.SEVERE, null, ex);
}
}

static private class MyHttpHandler implements HttpHandler {

@Override

public void handle(HttpExchange httpExchange) throws IOException {

String requestParamValue=null;

if("GET".equals(httpExchange.getRequestMethod())) {

requestParamValue = handleGetRequest(httpExchange);

}else if("POST".equals(httpExchange)) {

//requestParamValue = handlePostRequest(httpExchange);

}

handleResponse(httpExchange,requestParamValue);

}

private String handleGetRequest(HttpExchange httpExchange) {

return httpExchange.

getRequestURI()

.toString()

.split("\\?")[1]

.split("=")[1];

}

private void handleResponse(HttpExchange httpExchange, String requestParamValue) throws IOException {

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

String htmlResponse = StringEscapeUtils.escapeHtml4(htmlBuilder.toString());

// this line is a must

httpExchange.sendResponseHeaders(200, htmlResponse.length());

outputStream.write(htmlResponse.getBytes());

outputStream.flush();

outputStream.close();

}

}
}

output
open in broser
http://localhost:8001/test?name=chandu

Java HttpServer Example

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