Question

我用Java创建了一个代理服务器，（参见下面的代码），问题是，我从Web服务器得到响应但是我的客户端代理处理客户端之间的连接（浏览器）和代理服务器端创建套接字后的Web服务器。服务器端创建客户端并发送请求和套接字，然后在新线程中处理。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服务器端

在浏览器/代理/网络服务器之间发送数据时，我应该使用哪种类型的流？
使用字符串是否可以，或者在从流中发送和接收时是否应该使用某种类型的字节数组？
为什么浏览器没有从代理接收任何内容？因为我可以从控制台打印出来，但是当写入流时，浏览器中没有任何反应。

另外，为什么我需要在浏览器中点击“输入”两次才能让代理做出反应？

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

扔掉它。这不是代理的编写方式。 HTTP代理应该：

从下游客户端读取一行行，以确定连接到上游的用户，而不进行缓冲。
连接上游。
如果（2）失败，请向下游发送适当的HTTP响应并关闭连接。
否则，开始双向同时复制字节

你应该不尝试组装整个请求，甚至是标题，并且上面的“字节”和“同时”这两个词是至关重要的。请注意，您不必对HTTP保持活动，for(i in seq_along(data)){ Hmisc::label(data[, i]) <- var.labels[i] } label(data) #> age sex #> "Age in Years" "Sex of the participant"标头，HTTPS等执行任何操作。

Java代理不向浏览器发送任何内容

1 个答案: