import com.sun.net.httpserver.Filter;
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 com.sun.net.httpserver.SimpleFileServer;
import org.jetbrains.annotations.NotNull;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.function.Predicate;
/**
* <a href="https://www.baeldung.com/simple-web-server-java-18">simple-web-server-java-18</a>
* If you need socket level implementation <a href="https://dev.to/mateuszjarzyna/build-your-own-http-server-in-java-in-less-than-one-hour-only-get-method-2k02">Using socket</a>
*/
public class MyServer {
static class MyItemHandler implements HttpHandler {
/**
* Handle the http://localhost:8080/item?name=tv
* request and generate an appropriate response.
* See {@link HttpExchange} for a description of the steps
* involved in handling an exchange.
*
* @param exchange the exchange containing the request from the
* client and used to send the response
*/
@Override
public void handle(HttpExchange exchange) throws IOException {
final String requestMethod = exchange.getRequestMethod();
final String requestUri = exchange.getRequestURI().toString();
Map<String, String> queryMap = getQueryMap(requestUri);
String requestParamValue = queryMap.entrySet().iterator().next().getValue();
if (requestMethod.equals("GET")) {
final OutputStream responseBody = exchange.getResponseBody();
// you can send encoded html message as well
final String userMessage = "Hello World";
StringBuilder htmlBuilder = new StringBuilder();
htmlBuilder
.append("<html>")
.append("<body>")
.append("<h1>")
.append("Hello ")
.append(requestParamValue)
.append("</h1>")
.append("</body>")
.append("</html>");
byte[] userMessageBytes;
if (requestParamValue != null && !requestParamValue.isBlank()) {
userMessageBytes = htmlBuilder.toString().getBytes(StandardCharsets.UTF_8);
} else {
userMessageBytes = userMessage.getBytes(StandardCharsets.UTF_8);
}
//following code is must and order is important, i.e. set status code first before writing body
exchange.sendResponseHeaders(200, userMessageBytes.length);
responseBody.write(userMessageBytes);
responseBody.flush();
responseBody.close();
}
}
}
public static void main(String[] args) throws IOException, InterruptedException {
// Prepare thread pool
final ExecutorService executorService = Executors.newFixedThreadPool(10);
final int port = 8080;
// Filters
Filter filter = SimpleFileServer.createOutputFilter(System.out, SimpleFileServer.OutputLevel.INFO);
// Global handlers
HttpHandler allowedResponse = HttpHandlers.of(200, Headers.of("Allow", "GET"), "Welcome");
HttpHandler deniedResponse = HttpHandlers.of(401, Headers.of("Deny", "GET"), "Denied");
Predicate<Request> findAllowedPath = r -> r.getRequestURI()
.getPath().equals("/test/allowed");
HttpHandler handler = HttpHandlers.handleOrElse(findAllowedPath, allowedResponse, deniedResponse);
final HttpServer server = HttpServer.create(new InetSocketAddress(port), 0, "/", handler, filter);
server.setExecutor(executorService);
// Custom Handlers
server.createContext("/item", new MyItemHandler());
server.start();
System.out.println(" Server started on port " + port);
}
@NotNull
private static Map<String, String> getQueryMap(String requestUri) {
if (requestUri == null || requestUri.isBlank()) {
return Collections.emptyMap();
}
Map<String, String> queryMap = new HashMap<>();
final String[] requestParams = requestUri.split("\\?");
if (requestParams.length > 0) {
final String[] queryParam = requestParams[1].split("&");
for (String s : queryParam) {
final String[] requestValue = s.split("=");
if (requestValue.length > 0) {
queryMap.put(requestValue[0], requestValue[1]);
}
}
}
return queryMap;
}
}import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
/**
* <a href="https://www.baeldung.com/java-httpclient-post">java-httpclient-usage</a>
* <a href="https://www.vogella.com/tutorials/JavaHttpClient/article.html">httpclient-fluent-api</a>
*/
public class MyClient {
public static void main(String[] args) {
try (var httpClient = HttpClient.newHttpClient()) {
// use the client
final String url = "http://localhost:8080/item?item1=tv&item2=cd&item3=mouse";
syncApiCall(url, httpClient);
asyncApiCall(url, httpClient);
}
}
private static void asyncApiCall(String url, HttpClient httpClient) {
final HttpRequest httpRequest = HttpRequest.newBuilder(URI.create(url)).GET().header("User-Agent", "Mozilla/5.0").build();
try {
final CompletableFuture<HttpResponse<String>> httpResponse = httpClient.sendAsync(httpRequest, HttpResponse.BodyHandlers.ofString());
System.out.println(httpResponse.get().statusCode() + ":" + httpResponse.get().body());
} catch (InterruptedException | ExecutionException e) {
throw new RuntimeException(e);
}
}
private static void syncApiCall(String url, HttpClient httpClient) {
final HttpRequest httpRequest = HttpRequest.newBuilder(URI.create(url)).GET().header("User-Agent", "Mozilla/5.0").build();
try {
final HttpResponse<String> httpResponse = httpClient.send(httpRequest, HttpResponse.BodyHandlers.ofString());
System.out.println(httpResponse.statusCode() + ":" + httpResponse.body());
} catch (IOException | InterruptedException e) {
throw new RuntimeException(e);
}
}
}