Creating a Frameworkless HTTP Server in Java Packaged as a JAR for Docker Placeholder

2025-11-14

Java Code

import com.sun.net.httpserver.HttpServer;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpExchange;
import java.io.IOException;
import java.io.OutputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.net.InetSocketAddress;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Collectors;

public class SimpleHttpServer {
    public static void main(String[] args) throws IOException {
        HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0);
        server.createContext("/", new EchoHandler());
        server.setExecutor(null);
        server.start();
        System.out.println("Server started on port 8080");
    }

    static class EchoHandler implements HttpHandler {
        @Override
        public void handle(HttpExchange exchange) throws IOException {
            try {
                // Parse request components
                String requestUri = exchange.getRequestURI().toString();
                String queryParams = exchange.getRequestURI().getQuery();
                String requestBody = getRequestBody(exchange);

                // Build response
                String response = buildHtmlResponse(requestUri, queryParams, requestBody);
                String logMessage = buildLogMessage(requestUri, queryParams, requestBody);

                // Send response and log
                exchange.sendResponseHeaders(200, response.getBytes().length);
                try (OutputStream os = exchange.getResponseBody()) {
                    os.write(response.getBytes());
                }
                System.out.println(logMessage);
            } catch (Exception e) {
                e.printStackTrace();
                String errorResponse = "Error processing request: " + e.getMessage();
                exchange.sendResponseHeaders(500, errorResponse.getBytes().length);
                try (OutputStream os = exchange.getResponseBody()) {
                    os.write(errorResponse.getBytes());
                }
            }
        }

        private String getRequestBody(HttpExchange exchange) throws IOException {
            try (BufferedReader br = new BufferedReader(
                    new InputStreamReader(exchange.getRequestBody(), "UTF-8"))) {
                return br.lines().collect(Collectors.joining("\n"));
            }
        }

        private String buildHtmlResponse(String uri, String params, String body) {
            return "&lt;html&gt;&lt;body&gt;" +
                   "&lt;h1&gt;Request Details&lt;/h1&gt;" +
                   "&lt;p&gt;&lt;strong&gt;URI:&lt;/strong&gt; " + uri + "&lt;/p&gt;" +
                   "&lt;p&gt;&lt;strong&gt;Query Parameters:&lt;/strong&gt; " + (params != null ? params : "None") + "&lt;/p&gt;" +
                   "&lt;p&gt;&lt;strong&gt;Request Body:&lt;/strong&gt;&lt;br/&gt;&lt;pre&gt;" + body + "&lt;/pre&gt;&lt;/p&gt;" +
                   "&lt;/body&gt;&lt;/html&gt;";
        }

        private String buildLogMessage(String uri, String params, String body) {
            return String.format("Request Received:\nURI: %s\nParams: %s\nBody: %s\n", 
                uri, params != null ? params : "None", body);
        }
    }
}

Compilation and Packaging

# Clean previous artifacts
del *.class, SimpleHttpServer.jar

# Recompile source
javac SimpleHttpServer.java

# Create JAR with direct main class specification (no external manifest needed)
jar --create --file SimpleHttpServer.jar --main-class SimpleHttpServer -C . .

# Run the server
java -jar SimpleHttpServer.jar

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