httpurlconnectiontimeout.java

这是一个matlab的java实现。里面有许多内容。请大家慢慢捉摸。

package edu.umass.cs.mallet.projects.dex.web;
import java.net.*;
import java.io.*;
import sun.net.www.http.HttpClient;

public class HttpURLConnectionTimeout extends sun.net.www.protocol.http.HttpURLConnection
{
    int fiTimeoutVal;
    HttpTimeoutHandler fHandler;
    HttpClientTimeout fClient;
    public HttpURLConnectionTimeout(URL u, HttpTimeoutHandler handler, int iTimeout) throws IOException
    {   
    	super(u, handler);
	fiTimeoutVal = iTimeout;
    }
    
    public HttpURLConnectionTimeout(URL u,  String host, int port) throws IOException
    {  
    	super(u, host, port);
    }
    
    public void connect() throws IOException {
	if (connected) {
	    return;
	}
	try {
	    if ("http".equals(url.getProtocol()) /* && !failedOnce <- PRIVATE */ ) {
		// for safety's sake, as reported by KLGroup
		synchronized (url)
		    {
			http = HttpClientTimeout.GetNew(url);
		    }
		fClient = (HttpClientTimeout)http;
   		((HttpClientTimeout)http).SetTimeout(fiTimeoutVal);
	    } else {
		// make sure to construct new connection if first
		// attempt failed
		http = new HttpClientTimeout(url, fHandler.GetProxy(), fHandler.GetProxyPort());
	    }
	    ps = (PrintStream)http.getOutputStream();
	} catch (IOException e) {
	    throw e;  }
	// this was missing from the original version
	connected = true;
    }
    
    /**
     * Create a new HttpClient object, bypassing the cache of
     * HTTP client objects/connections.
     *
     * @param url	the URL being accessed
     */
    protected HttpClient getNewClient (URL url)
	throws IOException {
	HttpClientTimeout client = new HttpClientTimeout (url, (String)null, -1);
	try {
	    client.SetTimeout(fiTimeoutVal);
	} catch (Exception e) 
	    { System.out.println("Unable to set timeout value"); }
	return (HttpClient)client; 
    }
    
    /**
     * opens a stream allowing redirects only to the same host.
     */
    public static InputStream openConnectionCheckRedirects(URLConnection c)
	throws IOException
    {
        boolean redir;
        int redirects = 0;
        InputStream in = null;
	
        do {
            if (c instanceof HttpURLConnectionTimeout) {
                ((HttpURLConnectionTimeout) c).setInstanceFollowRedirects(false);
            }
	    
            // We want to open the input stream before
            // getting headers, because getHeaderField()
            // et al swallow IOExceptions.
            in = c.getInputStream();
            redir = false;
	    
            if (c instanceof HttpURLConnectionTimeout) {
                HttpURLConnectionTimeout http = (HttpURLConnectionTimeout) c;
                int stat = http.getResponseCode();
                if (stat >= 300 && stat <= 305 &&
		    stat != HttpURLConnection.HTTP_NOT_MODIFIED) {
                    URL base = http.getURL();
                    String loc = http.getHeaderField("Location");
                    URL target = null;
                    if (loc != null) {
                        target = new URL(base, loc);
                    }
                    http.disconnect();
                    if (target == null
                        || !base.getProtocol().equals(target.getProtocol())
                        || base.getPort() != target.getPort()
                        || !HostsEquals(base, target)
                        || redirects >= 5)
			{
			    throw new SecurityException("illegal URL redirect");
			}
                    redir = true;
                    c = target.openConnection();
                    redirects++;
                }
            }
        } while (redir);
        return in;
    }
    
    // Same as java.net.URL.hostsEqual
    
    
    static boolean HostsEquals(URL u1, URL u2) 
    { 
        final String h1 = u1.getHost();
        final String h2 = u2.getHost();
	
        if (h1 == null) {
            return h2 == null;
        } else if (h2 == null) {
            return false;
        } else if (h1.equalsIgnoreCase(h2)) {
            return true;
        }
	// Have to resolve addresses before comparing, otherwise
	// names like tachyon and tachyon.eng would compare different
        final boolean result[] = {false};
	
        java.security.AccessController.doPrivileged
	    (
	     new java.security.PrivilegedAction() {
		 public Object run() {
		     try {
			 InetAddress a1 = InetAddress.getByName(h1);
			 InetAddress a2 = InetAddress.getByName(h2);
			 result[0] = a1.equals(a2);
		     } catch(UnknownHostException e) {
		     } catch(SecurityException e) {
		     }
		     return null;
		 }
	     });
	
        return result[0];
    }
    
    void Close() throws Exception
    {
	fClient.Close();
    }
    
    Socket GetSocket()
    {
	return fClient.GetSocket();
    }
}