Java中的代理-客户端不显示响应?
我的编程任务要求我在客户端和服务器之间创建一个代理。 我的客户机通过代理向服务器发出请求,然后代理将其转发,并将服务器的响应返回给客户机 以下是我采取的步骤: 1) 从客户端获取请求并将请求数据存储到字节数组中 2) 使用缓冲读取器从字节数组中读取 3) 从host:header字段获取主机名,并使用它创建一个serverSocket 4) 将请求数据转发到serverSocket outputstream 5) 将响应数据从serverSocket inputstream检索到另一个字节数组中 6) 将字节数组中的内容写入clientSocket输出流 但是,在步骤6之后,浏览器无法显示响应数据。有什么帮助吗Java中的代理-客户端不显示响应?,java,sockets,http,proxy,Java,Sockets,Http,Proxy,我的编程任务要求我在客户端和服务器之间创建一个代理。 我的客户机通过代理向服务器发出请求,然后代理将其转发,并将服务器的响应返回给客户机 以下是我采取的步骤: 1) 从客户端获取请求并将请求数据存储到字节数组中 2) 使用缓冲读取器从字节数组中读取 3) 从host:header字段获取主机名,并使用它创建一个serverSocket 4) 将请求数据转发到serverSocket outputstream 5) 将响应数据从serverSocket inputstream检索到另一个字节数组中
import java.io.*;
import java.net.*;
import java.util.*;
public class proxy2 {
public static void main(String args[]) throws Exception
{
int port = Integer.parseInt(args[0]);
File fileSub= new File(args[1]); //fileSub
File fileRediect = new File(args[2]); //fileRedirect
ServerSocket listener = new ServerSocket(port);
while (true) {
proxy_func(listener.accept());
}
}
public static void proxy_func(Socket clientSocket) throws Exception{
OutputStream outputToClient = clientSocket.getOutputStream();
//store clientSocket's inputstream into a buffer
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int nRead; //start offset in the data
byte[] data = new byte[16384]; //create byte array
//read each byte from InputStream and write it to a ByteArrayOutputStream
while((nRead = clientSocket.getInputStream().read(data, 0, data.length)) != -1) {
buffer.write(data, 0, nRead);
}
buffer.flush(); //forces any buffered bytes to be written out
data = buffer.toByteArray(); //retrieve the underlying byte array
System.out.println(new String(data));
//create buffer reader for clientSocket's inputstream
InputStream inputStream = new ByteArrayInputStream(data);
BufferedReader readFromClient = new BufferedReader(new InputStreamReader(inputStream));
String[] strArr;
String line;
String hostname = null;
//get hostname
while( (line=readFromClient.readLine()) != null)
{
strArr = line.split(" ");
if(strArr[0].equals("Host:"))
hostname = strArr[1];
}
System.out.println("Host: " + hostname);
//create server socket
Socket serverSocket = new Socket(hostname, 80);
OutputStream outputToServer = serverSocket.getOutputStream();
InputStream inputFromServer = serverSocket.getInputStream();
//forward request to server
System.out.println("forward request to server...");
outputToServer.write(data);
//receive data from server and write response back to client
byte[] receivedData = new byte[16384];
int size;
while((size = inputFromServer.read(receivedData)) != -1)
{
System.out.println("write response back to client...");
System.out.println("size: " + size);
System.out.println(new String(receivedData));
outputToClient.write(receivedData, 0, size);
}
System.out.println("flushing...");
outputToClient.flush();
outputToClient.close();
}
}
因此,我基本上遵循以下I/O布局:
{
OutputStream outputToClient = clientSocket.getOutputStream();
BufferedReader readFromClient = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
//step 1
//get the HTTP request header from your firefox
String line = readFromClient.readLine();
//if the Content_Length within the HTTP header exists and not equals to 0
char [] buffer = new char [#];
readFromClient.read(buffer, 0, Content_Length); //get the body message
OutputStream outputToServer = serverSocket.getOutputStream();
InputStream inputFromServer = serverSocket.getInputStream();
//step 2
outputToServer.write(Bytes[]) //forword the HTTP requests to server host.
//step 3
byte[] data = new byte[#];
while ((size = inputFromServer.read(data)) != -1) //get the response data from server
{
//step 4
outputToClient.write(data, 0, size); //forward the data to your firefox
}
}
最后一部分有一个问题:
byte[] receivedData = new byte[16384];
int size;
while((size = inputFromServer.read(receivedData)) != -1)
{
System.out.println("write response back to client...");
System.out.println("size: " + size);
System.out.println(new String(receivedData));
}
outputToClient.write(receivedData);
那么,假设服务器发回100万字节。循环按16384字节的块读取它们,一旦它读取了所有的块,它会在上次读取之后将receivedData
缓冲区中剩余的内容发回。因此,浏览器将只接收服务器发送的1000000字节中的16384字节
您必须将从服务器读取的所有内容发送到浏览器:
byte[] receivedData = new byte[16384];
int size;
while((size = inputFromServer.read(receivedData)) != -1)
{
System.out.println("write response back to client...");
System.out.println("size: " + size);
System.out.println(new String(receivedData));
outputToClient.write(receivedData, 0, size);
}
好的,我找到了问题的原因。我的while循环被阻止,因为我没有检测到HTTP请求的结束。这个答案简明扼要地解决了我的问题: 这里只是为那些偶然发现这个问题并迷路的人发的帖子 下面是我的更新代码,可以使用(注意,我添加了一个方法来检测HTTP请求的结束):
你做错了。HTTP代理只需读取CONNECT命令并对其执行操作。之后,您只需尽可能快地同时在两个方向上复制字节。您越是试图理解代理中的HTTP协议,就会引入越多的错误。嘿,谢谢您的回复。事实上,我以前实施过你的方法,但没有成功。我用你编辑的代码更新了我的答案。你知道还有什么其他的方法可以让它起作用吗?定义“没有起作用”。发生了什么。你的日志怎么说?您在Firebug网络控制台上看到了什么?我可以在控制台上看到打印的响应数据(我使用cmd运行),但我的浏览器无法显示响应数据,即它仍在等待响应。
import java.io.*;
import java.net.*;
import java.util.*;
public class proxy2 {
public static void main(String args[]) throws Exception
{
int port = Integer.parseInt(args[0]);
File fileSub= new File(args[1]); //fileSub
File fileRediect = new File(args[2]); //fileRedirect
//create listener socket to listen for requests from browser
ServerSocket listener = new ServerSocket(port);
while (true) {
proxy_func(listener.accept());
}
}
public static void proxy_func(Socket clientSocket) throws Exception{
OutputStream outputToClient = clientSocket.getOutputStream();
InputStream inputFromClient = clientSocket.getInputStream();
//store clientSocket's inputstream into a buffer
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int nRead; //start offset in the data
byte[] data = new byte[16384];
//read each byte from InputStream and write it to a ByteArrayOutputStream
while((nRead = inputFromClient.read(data, 0, data.length)) != -1) {
System.out.println("reading from client...");
buffer.write(data, 0, nRead);
//if reached end of HTTP request, break out of this loop
if(endOfRequest(data) == true)
break;
}
buffer.flush(); //forces any buffered bytes to be written out
data = buffer.toByteArray(); //retrieve the underlying byte array
System.out.println(new String(data));
//create buffered reader for byte array input stream (request data)
InputStream inputStream = new ByteArrayInputStream(data);
BufferedReader readFromClient = new BufferedReader(new InputStreamReader(inputStream));
String[] strArr;
String line;
String hostname = null;
//get hostname
while( (line=readFromClient.readLine()) != null)
{
strArr = line.split(" ");
if(strArr[0].equals("Host:"))
hostname = strArr[1];
}
System.out.println("Host: " + hostname);
//create server socket
Socket serverSocket = new Socket(hostname, 80);
OutputStream outputToServer = serverSocket.getOutputStream();
//InputStream inputFromServer = serverSocket.getInputStream();
//forward request to server
System.out.println("forward request to server...");
outputToServer.write(data);
//receive data from server and write response back to client
DataInputStream inputFromServer = new DataInputStream(serverSocket.getInputStream());
byte[] receivedData = new byte[1024];
int size;
while((size = inputFromServer.read(receivedData, 0, receivedData.length)) != -1)
{
System.out.println("write response back to client...");
System.out.println(new String(receivedData));
outputToClient.write(receivedData, 0, size);
outputToClient.flush();
}
System.out.println("done sending");
outputToClient.close();
}
//method to detect end of HTTP request
//return true if detected, otherwise false
public static boolean endOfRequest(byte[] data) throws Exception
{
System.out.println("parsing request..");
BufferedReader br = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(data)));
String line;
while( (line=br.readLine()) != null) {
if (line.equals(""))
return true;
}
return false;
}
}