Java HttpURLConnection Open openConnectionCheckRedirects(URLConnection c)

Description

open Connection Check Redirects

License

Apache License

Declaration

public static InputStream openConnectionCheckRedirects(URLConnection c) throws IOException 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;

public class Main {
    public static InputStream openConnectionCheckRedirects(URLConnection c) throws IOException {
        boolean redir;
        int redirects = 0;
        InputStream in = null;//from  w w w.j ava2s .  c om
        do {
            if (c instanceof HttpURLConnection) {
                ((HttpURLConnection) 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 HttpURLConnection) {
                HttpURLConnection http = (HttpURLConnection) c;
                int stat = http.getResponseCode();
                if (stat >= 300 && stat <= 307 && stat != 306 && 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();
                    // Redirection should be allowed only for HTTP and HTTPS
                    // and should be limited to 5 redirections at most.
                    if (target == null
                            || !(target.getProtocol().equals("http") || target.getProtocol().equals("https"))
                            || redirects >= 5) {
                        throw new SecurityException("illegal URL redirect");
                    }
                    redir = true;
                    c = target.openConnection();
                    redirects++;
                }
            }
        } while (redir);
        return in;
    }
}

Related

1. getConnectionStream(HttpURLConnection con)
2. openConnection(final String urlString)
3. openConnection(final URL url, final String requestMethod)
4. openConnection(String url, String method, String contentType, String ssic)
5. openConnection(URL url, Proxy proxy)