Question

尝试用Java编写一个非常简单，简单的线程HTTP代理服务器我取得了很好的进展：

客户端连接到服务器，输入和输出流向客户端的流程
目标网址是从GET请求中提取的
与目标Web服务器建立连接，并建立输入流

现在我明白我需要发送来自服务器输入流的数据并转发它到客户端输出流，但如何正确地做到这一点逃避了我。我的经验延伸输入和输出流一直在发送单个字符串，而且我还不太稳固了解这些流的确切运作方式。

我是否应该将输入流中的所有数据读入文件，然后写入输出流？有更优雅的解决方案吗？

这是我的代码：

import java.io.*;
import java.net.*;
import java.util.*;

public class Proxy {

/////////////////////////////////////
public static void go(){

int incomingport = 50000;
ServerSocket myproxysocket = null;

try{
myproxysocket = new ServerSocket(incomingport);
while(true){
System.out.println("HTTP Java Proxy Server");
System.out.println();
System.out.println("Listening on port 50000...Press CTRL+C to exit");
System.out.println();
Socket client = myproxysocket.accept();
Thread t = new Thread(new ClientHandler(client));
t.start();
}//end while
}//end try

catch(Exception E){
E.printStackTrace();    
}
}//end method go()

///////////////////////////////////
public static void main(String args[]) {

Proxy myserver =  new Proxy();
myserver.go();

}//end main
}//end class proxy


/////////////////////////////////////////////////////////////////////////////////////
class ClientHandler implements Runnable{

private final DataInputStream clientin;
private final DataOutputStream clientout;
private final Socket clientSocket;


//constructor----------------
public ClientHandler(Socket incomingSocket) throws IOException{

clientSocket = incomingSocket; 
clientin = new DataInputStream(incomingSocket.getInputStream());
clientout = new DataOutputStream(incomingSocket.getOutputStream());


}//--------------------------

////////////////////
public void run(){
try{

//Get URL from client
String getrequestline = clientin.readLine();
String targetURL = null;
String clientIP = null;
StringTokenizer st = new StringTokenizer(getrequestline);
st.nextToken();
targetURL = st.nextToken();
clientIP = clientSocket.getRemoteSocketAddress().toString();
System.out.println();
System.out.println("IP: " + clientIP);
System.out.println("Requested URL: " + targetURL);
System.out.println();

//connect to target URL
URL url = new URL(targetURL);
URLConnection targetconnection = url.openConnection();
targetconnection.setDoInput(true);
targetconnection.setDoOutput(false);


InputStream is = targetconnection.getInputStream();

//How do I read in from is and write out to clientout?

//clientout.write(???????)

}//try
catch(Exception E){
 E.printStackTrace();
}//catch
finally{
try{clientSocket.close();}
catch(Exception ee){}
}//finally
}//end run----------

}//end CLASS--------------------------------------------------------------------------

Answer 1

中有一个非常简洁的实用工具类

org.apache.commons.io.IOUtils

来自commons-io包的那些。如果可以，请使用它。否则，一个简单的方法（不使用任何NIO的东西）就是这样：

public static void copy(InputStream is, OutputStream os) throws IOException {
    byte[] buff = new byte[1024*1024];
    int a = 0;
    while((a = is.read(buff)) > -1) {

        // a is the number of bytes ACTUALLY read, so 
        // when we write, that's the number of bytes to write
        os.write(buff,0,a);
    }
    os.flush();
}

并且像往常一样，不要忘记冲洗。

与代理的输入/输出流混淆

1 个答案: