Java代理未将任何内容发送回浏览器

Question

我已经用Java创建了一个代理服务器（请参见下面的代码），问题是，我从Web服务器获取了响应，但是代理的客户端处理了客户端（浏览器）和Web之间的连接在使用代理的服务器端创建套接字后，使用-server。 服务器端创建一个客户端，并发送请求和套接字，然后在新线程中对其进行处理。 我有几个问题：

第一个代码属于代理的客户端，第二个代码部分属于代理的服务器端

• 在浏览器/代理/网络服务器之间发送数据时应使用哪种类型的流？

• 从流发送和接收时，使用String是否合适还是应该使用某种类型的字节数组？

• 为什么浏览器没有收到来自代理的任何信息？ 由于我可以从控制台中将其打印出来，但是当写入流时，浏览器中什么也没有发生。

• 另外，为什么我需要在浏览器中单击两次“输入”以使代理作出反应？

   public class Client implements Runnable { private String request; private String response; private Socket browserSocket; public Client(String request, Socket browserSocket) { this.request = request; this.response = ""; this.browserSocket = browserSocket; } @Override public void run() { /* Send request to web server and get the response. */ this.request = Client.modifyHttpHeader("Connection", "close", this.request); String hostName = Client.getHttpHeader("Host", this.request); if (!hostName.isEmpty()) { try { /* Send request to the web-server. */ Socket socket = new Socket(hostName, 80); OutputStreamWriter osw = new OutputStreamWriter(socket.getOutputStream()); PrintWriter pw = new PrintWriter(osw); pw.write(this.request); pw.flush(); System.out.println("---S:REQUEST---"); System.out.println(this.request); System.out.println("---S:REQUEST---"); /* Receive the response from the web-server. */ BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream())); String response = ""; int tmpData; while ((tmpData = br.read()) != -1) { response += (char)tmpData; } this.response = response; socket.close(); /* Close the socket between client-side and web-server. */ /* Send the response back to the browser. */ OutputStreamWriter oswbrowser = new OutputStreamWriter(this.browserSocket.getOutputStream()); PrintWriter pwBrowser = new PrintWriter(oswbrowser); pwBrowser.write(this.response); pwBrowser.flush(); pwBrowser.close(); this.browserSocket.close(); /* Close the socket between client-side and browser. */ System.out.println("---C:RESPONSE---"); System.out.println(this.response); System.out.println("---C:RESPONSE---"); } catch (Exception e) { System.err.println(e.getMessage()); e.printStackTrace(); } } } public String getHttpResponse() { return this.response; } /** * * @param header * The name of the HTTP header. Example: "GET". * Note: Header name is case sensitive. * @param request * The HTTP message. * @return * On success: The value following the HTTP header ": " (colon and whitespace). * On failure: Empty string. */ public static String getHttpHeader(String header, String request) { int startHeaderIndex = request.indexOf(header) + header.length(); int endHeaderIndex = request.indexOf('\\n', startHeaderIndex); /* Could not find the searched header. */ if (startHeaderIndex == -1 || endHeaderIndex == -1) return ""; /* Add 2 to remove ':' and ' '(white space). Decrement 1 to exclude '\\r' and '\\n' */ return request.substring(startHeaderIndex + 2, endHeaderIndex - 1); } /** * * @param header * The name of the HTTP header. Example: "Connection" * Note: The header is case sensitive. * @param value * The new value you want to put. Example: "Close" * @param request * The HTTP message. * @return * On success: A new HTTP request with the modified header value. * On failure: Empty string. * */ public static String modifyHttpHeader(String header, String value, String request) { int startHeaderIndex = request.indexOf(header) + header.length(); int endHeaderIndex = request.indexOf('\\n', startHeaderIndex); /* Could not find the searched header. */ if (startHeaderIndex == -1 || endHeaderIndex == -1) return ""; String newRequest = ""; /* Copy all characters including ':' and ' ' (whitespace) */ for (int i = 0; i < startHeaderIndex + 2; i++) { newRequest += request.charAt(i); } newRequest += value; newRequest += "\\r\\n"; /* Add the rest of the request. */ for (int i = endHeaderIndex + 1; i < request.length(); i++) { newRequest += request.charAt(i); } return newRequest; } } public class Server { public static void main(String[] args) throws Exception{ /* Receiving and parsing port number from command line arguments. */ int ssPort = 0; if (args.length > 1 || args.length == 0){ System.err.println("Only one argument allowed; port number (int)."); System.exit(1); } else { try { ssPort = Integer.parseInt(args[0]); } catch(NumberFormatException exception) { System.err.println("Argument \\"" + args[0] + "\\" must be a number."); System.exit(1); } } ServerSocket serverSocket = new ServerSocket(ssPort); /* Creating the server socket. */ System.out.println("Proxy running on port: " + ssPort); while(true) { System.out.println("Waiting for client..."); Socket clientSocket = serverSocket.accept(); /* Listening for connections. */ BufferedReader bReader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); String request = ""; int tmpData; while ((tmpData = bReader.read()) != -1) { request += (char)tmpData; } Client clientObject = new Client(request, clientSocket); Thread clientThread = new Thread(clientObject); clientThread.start(); /* Start the client thread. */ } } 

  }

Answer 1

扔了这一切。 代理不是这样写的。 HTTP代理应：

1. 阅读来自下游客户端一行 ，以确定谁连接到上游，没有缓冲。
2. 连接上游。
3. 如果（2）失败，则向下游发送适当的HTTP响应并关闭连接。
4. 否则，请同时开始双向复制字节 。

不应尝试组装整个请求，或甚至标头，和上面的字“字节”和“同时”是至关重要的。 请注意，您无需执行任何有关HTTP保持活动， Connection头，HTTPS等的操作。