只需几行代码就可以创建一个仅使用JDK和servlet api提供J2EE servlet基本支持的httpserver。

我发现这对于单元测试servlet非常有用，因为它启动速度比其他轻量级容器快得多(我们在生产中使用jetty)。

大多数非常轻量级的httpserver都不支持servlet，但是我们需要它们，所以我想分享一下。

下面的示例提供了基本的servlet支持，或者为尚未实现的内容抛出和UnsupportedOperationException异常。它使用com.sun.net.httpserver.HttpServer来提供基本的http支持。

import java.io.*;
import java.lang.reflect.*;
import java.net.InetSocketAddress;
import java.util.*;

import javax.servlet.*;
import javax.servlet.http.*;

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

@SuppressWarnings("deprecation")
public class VerySimpleServletHttpServer {
    HttpServer server;
    private String contextPath;
    private HttpHandler httpHandler;

    public VerySimpleServletHttpServer(String contextPath, HttpServlet servlet) {
        this.contextPath = contextPath;
        httpHandler = new HttpHandlerWithServletSupport(servlet);
    }

    public void start(int port) throws IOException {
        InetSocketAddress inetSocketAddress = new InetSocketAddress(port);
        server = HttpServer.create(inetSocketAddress, 0);
        server.createContext(contextPath, httpHandler);
        server.setExecutor(null);
        server.start();
    }

    public void stop(int secondsDelay) {
        server.stop(secondsDelay);
    }

    public int getServerPort() {
        return server.getAddress().getPort();
    }

}

final class HttpHandlerWithServletSupport implements HttpHandler {

    private HttpServlet servlet;

    private final class RequestWrapper extends HttpServletRequestWrapper {
        private final HttpExchange ex;
        private final Map<String, String[]> postData;
        private final ServletInputStream is;
        private final Map<String, Object> attributes = new HashMap<>();

        private RequestWrapper(HttpServletRequest request, HttpExchange ex, Map<String, String[]> postData, ServletInputStream is) {
            super(request);
            this.ex = ex;
            this.postData = postData;
            this.is = is;
        }

        @Override
        public String getHeader(String name) {
            return ex.getRequestHeaders().getFirst(name);
        }

        @Override
        public Enumeration<String> getHeaders(String name) {
            return new Vector<String>(ex.getRequestHeaders().get(name)).elements();
        }

        @Override
        public Enumeration<String> getHeaderNames() {
            return new Vector<String>(ex.getRequestHeaders().keySet()).elements();
        }

        @Override
        public Object getAttribute(String name) {
            return attributes.get(name);
        }

        @Override
        public void setAttribute(String name, Object o) {
            this.attributes.put(name, o);
        }

        @Override
        public Enumeration<String> getAttributeNames() {
            return new Vector<String>(attributes.keySet()).elements();
        }

        @Override
        public String getMethod() {
            return ex.getRequestMethod();
        }

        @Override
        public ServletInputStream getInputStream() throws IOException {
            return is;
        }

        @Override
        public BufferedReader getReader() throws IOException {
            return new BufferedReader(new InputStreamReader(getInputStream()));
        }

        @Override
        public String getPathInfo() {
            return ex.getRequestURI().getPath();
        }

        @Override
        public String getParameter(String name) {
            String[] arr = postData.get(name);
            return arr != null ? (arr.length > 1 ? Arrays.toString(arr) : arr[0]) : null;
        }

        @Override
        public Map<String, String[]> getParameterMap() {
            return postData;
        }

        @Override
        public Enumeration<String> getParameterNames() {
            return new Vector<String>(postData.keySet()).elements();
        }
    }

    private final class ResponseWrapper extends HttpServletResponseWrapper {
        final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        final ServletOutputStream servletOutputStream = new ServletOutputStream() {

            @Override
            public void write(int b) throws IOException {
                outputStream.write(b);
            }
        };

        private final HttpExchange ex;
        private final PrintWriter printWriter;
        private int status = HttpServletResponse.SC_OK;

        private ResponseWrapper(HttpServletResponse response, HttpExchange ex) {
            super(response);
            this.ex = ex;
            printWriter = new PrintWriter(servletOutputStream);
        }

        @Override
        public void setContentType(String type) {
            ex.getResponseHeaders().add("Content-Type", type);
        }

        @Override
        public void setHeader(String name, String value) {
            ex.getResponseHeaders().add(name, value);
        }

        @Override
        public javax.servlet.ServletOutputStream getOutputStream() throws IOException {
            return servletOutputStream;
        }

        @Override
        public void setContentLength(int len) {
            ex.getResponseHeaders().add("Content-Length", len + "");
        }

        @Override
        public void setStatus(int status) {
            this.status = status;
        }

        @Override
        public void sendError(int sc, String msg) throws IOException {
            this.status = sc;
            if (msg != null) {
                printWriter.write(msg);
            }
        }

        @Override
        public void sendError(int sc) throws IOException {
            sendError(sc, null);
        }

        @Override
        public PrintWriter getWriter() throws IOException {
            return printWriter;
        }

        public void complete() throws IOException {
            try {
                printWriter.flush();
                ex.sendResponseHeaders(status, outputStream.size());
                if (outputStream.size() > 0) {
                    ex.getResponseBody().write(outputStream.toByteArray());
                }
                ex.getResponseBody().flush();
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                ex.close();
            }
        }
    }

    public HttpHandlerWithServletSupport(HttpServlet servlet) {
        this.servlet = servlet;
    }

    @SuppressWarnings("deprecation")
    @Override
    public void handle(final HttpExchange ex) throws IOException {
        byte[] inBytes = getBytes(ex.getRequestBody());
        ex.getRequestBody().close();
        final ByteArrayInputStream newInput = new ByteArrayInputStream(inBytes);
        final ServletInputStream is = new ServletInputStream() {

            @Override
            public int read() throws IOException {
                return newInput.read();
            }
        };

        Map<String, String[]> parsePostData = new HashMap<>();

        try {
            parsePostData.putAll(HttpUtils.parseQueryString(ex.getRequestURI().getQuery()));

            // check if any postdata to parse
            parsePostData.putAll(HttpUtils.parsePostData(inBytes.length, is));
        } catch (IllegalArgumentException e) {
            // no postData - just reset inputstream
            newInput.reset();
        }
        final Map<String, String[]> postData = parsePostData;

        RequestWrapper req = new RequestWrapper(createUnimplementAdapter(HttpServletRequest.class), ex, postData, is);

        ResponseWrapper resp = new ResponseWrapper(createUnimplementAdapter(HttpServletResponse.class), ex);

        try {
            servlet.service(req, resp);
            resp.complete();
        } catch (ServletException e) {
            throw new IOException(e);
        }
    }

    private static byte[] getBytes(InputStream in) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        while (true) {
            int r = in.read(buffer);
            if (r == -1)
                break;
            out.write(buffer, 0, r);
        }
        return out.toByteArray();
    }

    @SuppressWarnings("unchecked")
    private static <T> T createUnimplementAdapter(Class<T> httpServletApi) {
        class UnimplementedHandler implements InvocationHandler {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                throw new UnsupportedOperationException("Not implemented: " + method + ", args=" + Arrays.toString(args));
            }
        }

        return (T) Proxy.newProxyInstance(UnimplementedHandler.class.getClassLoader(),
                new Class<?>[] { httpServletApi },
                new UnimplementedHandler());
    }
}

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/

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。

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。

曾经有一段时间，我正在寻找类似的东西——一个轻量级但功能齐全的HTTP服务器，我可以轻松地嵌入和定制。我发现了两种可能的解决方案:

不是那么轻量级或简单的完整服务器(对于轻量级的极端定义)。 真正的轻量级服务器不是HTTP服务器，而是华丽的ServerSocket示例，甚至不远程兼容rfc，不支持通常需要的基本功能。

所以…我开始编写JLHTTP——Java轻量级HTTP服务器。

您可以将它作为单个(如果相当长)源文件嵌入到任何项目中，或者作为一个~50K的jar (~35K剥离)，没有依赖关系。它努力与rfc兼容，包括大量的文档和许多有用的特性，同时将膨胀保持在最低限度。

Features include: virtual hosts, file serving from disk, mime type mappings via standard mime.types file, directory index generation, welcome files, support for all HTTP methods, conditional ETags and If-* header support, chunked transfer encoding, gzip/deflate compression, basic HTTPS (as provided by the JVM), partial content (download continuation), multipart/form-data handling for file uploads, multiple context handlers via API or annotations, parameter parsing (query string or x-www-form-urlencoded body), etc.

我希望其他人会觉得有用:-)

查看NanoHttpd

NanoHTTPD是一个轻量级的HTTP服务器，设计用于嵌入其他应用程序，在Modified BSD许可下发布。

它正在Github开发，并使用Apache Maven进行构建和单元测试。”