一个非常基本的HTTP服务器在TCP套接字级别的例子:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

public class NaiveHttpServer {

  public static void main(String[] args) throws IOException {
    String hostname = InetAddress.getLocalHost().getHostName();
    ServerSocket serverSocket = new ServerSocket(8089);
    while (true) {
      Socket clientSocket = serverSocket.accept();
      PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
      BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
      String s = in.readLine();
      System.out.println(s);
      while ("\r\n".equals(in.readLine())); 
      if ("GET /hostname HTTP/1.1".equals(s)) {
        out.println("HTTP/1.1 200 OK");
        out.println("Connection: close");
        out.println("Content-Type: text/plain");
        out.println("Content-Length:" + hostname.length());
        out.println();
        out.println(hostname);
      } else {
        out.println("HTTP/1.1 404 Not Found");
        out.println("Connection: close");
        out.println();    
      }
      out.flush();
    }
  }
}

该示例提供计算机的主机名。

我喜欢这个问题，因为这是一个不断创新的领域，总是需要有一个轻型服务器，特别是当谈到小型设备中的嵌入式服务器时。我认为答案可以分为两大类。

瘦服务器:使用最少处理、上下文或会话处理的服务器式静态内容。 小型服务器:从表面上看，a具有许多类似httpd的服务器特性，并且占用的空间尽可能小。

虽然我可能会认为HTTP库，如:Jetty, Apache HTTP Components, Netty和其他更像一个原始的HTTP处理工具。标签是非常主观的，取决于你被要求为小网站提供的东西的种类。我是根据问题的精神，特别是关于……

＂...无需编写代码手动解析HTTP请求和手动格式化HTTP响应……”

These raw tools let you do that (as described in other answers). They don't really lend themselves to a ready-set-go style of making a light, embedded or mini-server. A mini-server is something that can give you similar functionality to a full-function web server (like say, Tomcat) without bells and whistles, low volume, good performance 99% of the time. A thin-server seems closer to the original phrasing just a bit more than raw perhaps with a limited subset functionality, enough to make you look good 90% of the time. My idea of raw would be makes me look good 75% - 89% of the time without extra design and coding. I think if/when you reach the level of WAR files, we've left the "small" for bonsi servers that looks like everything a big server does smaller.

瘦服务器选项

灰熊 UniRest(多语言) NanoHTTPD(只有一个文件)

Mini-server选项:

Spark Java…有了很多帮助器结构，比如过滤器、模板等，就有可能做得很好。 MadVoc……目标是成为盆景，而且很可能是这样;-)

Among the other things to consider, I'd include authentication, validation, internationalisation, using something like FreeMaker or other template tool to render page output. Otherwise managing HTML editing and parameterisation is likely to make working with HTTP look like noughts-n-crosses. Naturally it all depends on how flexible you need to be. If it's a menu-driven FAX machine it can be very simple. The more interactions, the 'thicker' your framework needs to be. Good question, good luck!

我强烈建议考虑Simple，特别是如果您不需要Servlet功能，而只是访问请求/响应对象。如果你需要REST，你可以把Jersey放在上面，如果你需要输出HTML或类似的东西，有Freemarker。我真的很喜欢使用这个组合可以做的事情，而且需要学习的API相对较少。

这是我简单的web服务器，在JMeter中用于测试webhook(这就是为什么它会在收到请求后关闭并结束自己)。

import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class HttpServer {

    private static int extractContentLength(StringBuilder sb) {
        int length = 0;
        String[] lines = sb.toString().split("\\n");
        for (int i = 0; i < lines.length; i++) {
            String s = lines[i];
            if (s.toLowerCase().startsWith("Content-Length:".toLowerCase()) && i <= lines.length - 2) {
                String slength = s.substring(s.indexOf(":") + 1, s.length()).trim();
                length = Integer.parseInt(slength);
                System.out.println("Length = " + length);
                return length;
            }
        }
        return 0;
    }

    public static void main(String[] args) throws IOException {
        
        
        int port = Integer.parseInt(args[0]);
        System.out.println("starting HTTP Server on port " + port);

        StringBuilder outputString = new StringBuilder(1000);

        ServerSocket serverSocket = new ServerSocket(port);
        serverSocket.setSoTimeout(3 * 60 * 1000); // 3 minutes timeout
        while (true) {

            outputString.setLength(0); // reset buff

            Socket clientSocket = serverSocket.accept(); // blocking
            PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);

            try {

                boolean isBodyRead = false;
                int dataBuffer;
                while ((dataBuffer = clientSocket.getInputStream().read()) != -1) {

                    if (dataBuffer == 13) { // CR
                        if (clientSocket.getInputStream().read() == 10) { // LF
                            outputString.append("\n");
                        }
                    } else {
                        outputString.append((char) dataBuffer);
                    }
                    
                    // do we have Content length
                    int len = extractContentLength(outputString);
                    if (len > 0) {
                        int actualLength = len - 1; // we need to substract \r\n
                        for (int i = 0; i < actualLength; i++) {
                            int body = clientSocket.getInputStream().read();
                            outputString.append((char) body);
                        }
                        isBodyRead = true;
                        break;
                    }

                } // end of reading while

                if (isBodyRead) {
                    // response headers
                    out.println("HTTP/1.1 200 OK");
                    out.println("Connection: close");
                    out.println(); // must have empty line for HTTP
                    
                    out.flush(); 
                    out.close(); // close clients connection
                }

            } catch (IOException ioEx) {
                System.out.println(ioEx.getMessage());
            }

            System.out.println(outputString.toString());
            break; // stop server - break while true
            
        } // end of outer while true
        
        serverSocket.close();

    } // end of method

}

你可以这样测试:

curl -X POST -H "Content-Type: application/json" -H "Connection: close" -d '{"name": "gustinmi", "email": "gustinmi at google dot com "}' -v http://localhost:8081/

从Java 11开始，旧的com.sun.net.httpserver再次成为一个公开且被接受的API。你可以把它作为HttpServer类，作为jdk的一部分。httpserver模块。参见https://docs.oracle.com/en/java/javase/11/docs/api/jdk.httpserver/com/sun/net/httpserver/HttpServer.html

这个类实现了一个简单的HTTP服务器。HttpServer绑定到一个IP地址和端口号，并侦听来自该地址上客户端的传入TCP连接。子类httpserver实现了一个处理HTTPS请求的服务器。

因此，除了它的局限性之外，没有理由再避免使用它了。

我使用它在服务器应用程序中发布控件接口。从客户端请求读取User-agent头，我甚至以文本/纯方式响应CLI工具，如curl或以更优雅的HTML方式响应任何其他浏览器。

很酷很简单。

检查拍摄。查看https://github.com/yegor256/takes获取快速信息