如何在Java中使用Google App Engine創建代理服務器？

Question

我想哈瓦用Java編寫的谷歌應用程序引擎的簡單代理服務器

servlet的是：

import java.io.*; 
import java.util.Enumeration; 
import java.util.Iterator; 
import java.util.Map; 
import java.util.List; 
import java.util.logging.*; 

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

import java.net.URL; 
import java.net.HttpURLConnection; 

public class ProxyServlet extends HttpServlet { 

    private ServletContext servletContext; 
    private Logger log; 

    public void init(ServletConfig servletConfig) throws ServletException { 
     servletContext = servletConfig.getServletContext(); 
     log = Logger.getLogger(ProxyServlet.class.getName()); 
    } 

    public void doGet(HttpServletRequest request, HttpServletResponse response){ 
     doPost(request, response); 
    } 

    public void doPost(HttpServletRequest request, HttpServletResponse response){ 
     System.out.println("doPost" ); 


     BufferedInputStream webToProxyBuf = null; 
     BufferedOutputStream proxyToClientBuf = null; 
     HttpURLConnection con; 

     try{ 
      int statusCode; 
      int oneByte; 
      String methodName; 
      String headerText; 

      String urlString = request.getRequestURL().toString(); 
      String queryString = request.getQueryString(); 

      urlString += queryString==null?"":"?"+queryString; 
      URL url = new URL(urlString); 

      log.info("Fetching >"+url.toString()); 

      con =(HttpURLConnection) url.openConnection(); 

      methodName = request.getMethod(); 
      con.setRequestMethod(methodName); 
      con.setDoOutput(true); 
      con.setDoInput(true); 
//   HttpURLConnection.setFollowRedirects(false); 
      con.setUseCaches(true); 

      for(Enumeration e = request.getHeaderNames() ; e.hasMoreElements();){ 
       String headerName = e.nextElement().toString(); 
       con.setRequestProperty(headerName, request.getHeader(headerName)); 
      } 

      con.connect(); 

      if(methodName.equals("POST")){ 
       BufferedInputStream clientToProxyBuf = new BufferedInputStream(request.getInputStream()); 
       BufferedOutputStream proxyToWebBuf  = new BufferedOutputStream(con.getOutputStream()); 

       while ((oneByte = clientToProxyBuf.read()) != -1) 
        proxyToWebBuf.write(oneByte); 

       proxyToWebBuf.flush(); 
       proxyToWebBuf.close(); 
       clientToProxyBuf.close(); 
      } 

      statusCode = con.getResponseCode(); 
      response.setStatus(statusCode); 

      for(Iterator i = con.getHeaderFields().entrySet().iterator() ; i.hasNext() ;){ 
       Map.Entry mapEntry = (Map.Entry)i.next(); 
       if(mapEntry.getKey()!=null) 
        response.setHeader(mapEntry.getKey().toString(), ((List)mapEntry.getValue()).get(0).toString()); 
      } 

      webToProxyBuf = new BufferedInputStream(con.getInputStream()); 
      proxyToClientBuf = new BufferedOutputStream(response.getOutputStream()); 

      StringBuffer sb = new StringBuffer(); 

      while ((oneByte = webToProxyBuf.read()) != -1) { 
       proxyToClientBuf.write(oneByte); 
       sb.append(oneByte); 
      } 

      System.out.println(sb); 

      proxyToClientBuf.flush(); 
      proxyToClientBuf.close(); 

      webToProxyBuf.close(); 
      con.disconnect(); 

     }catch(Exception e){ 
      System.out.println(e.getMessage()); 
      e.printStackTrace(); 
     } 
     finally{ 
     } 
    } 
} 

部署後，我設置Firefox的代理CONFIGS與代理HTTP = myproxyappname.appspot.com和端口= 80 ，但火狐瀏覽器只能在谷歌頁面衝浪

Answer 1

據我所知，你正在尋找一個託管在谷歌App Engine上的Web代理服務器。

這個問題已經在這個線程中討論過了。 Proxy for Google App Engine

你只需要移植python項目來實現java中的相同。

嘗試託管在GAE http://mirrorrr.appspot.com/

Answer 2

這裏本演示中的代理服務器是一個wprking代碼：

import java.io.File; 
import java.io.FileNotFoundException; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.OutputStream; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.util.HashMap; 
import java.util.Map; 
import java.util.Scanner; 

import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 



public class ProxyServlet extends HttpServlet { 



    @Override 
    protected void doGet(HttpServletRequest req, HttpServletResponse rsp) 
      throws ServletException, IOException { 
     try { 

      String fwdurlstring=req.getParameter("fwdurl"); 
      if(fwdurlstring==null) 
      { 
       fwdurlstring="http://www.mcbjam.com"; 
      } 


      URL fwdURL = new URL(fwdurlstring); 
      HttpURLConnection fwdConnection = 
       (HttpURLConnection) fwdURL.openConnection(); 

      for (String key : fwdConnection.getHeaderFields().keySet()) { 
       rsp.setHeader(key, fwdConnection.getHeaderField(key)); 
      } 

      copy(fwdConnection.getInputStream(), rsp.getOutputStream()); 

     } catch (Exception e) { 
      e.printStackTrace(rsp.getWriter()); 

     } 
    } 


    private void copy(InputStream in, OutputStream out) throws IOException { 
     int len = 0; 
     byte[] buf = new byte[1024]; 

     while ((len = in.read(buf)) > 0) { 
      out.write(buf, 0, len); 
     } 

     in.close(); 
    } 

} 

看到它在這裏的行動： http://paint.mcbjam.com/proxy?fwdurl=https://stackoverflow.com/questions/13194501/how-create-your-proxy-server-using-google-app-engine-in-java/16658914#16658914