Showing posts with label File Exists. Show all posts
Showing posts with label File Exists. Show all posts

Wednesday, December 5, 2012

Java check if file exists on remote server using its url

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

public class URLUtils {

  public static void main(String s[]) {
    System.out.println(URLUtils.exists("http://www.test.com/exists.html"));
    System.out.println(URLUtils.exists("http://www.test.com/no_exists.html"));
    /*
      output :
        true
        false
    */    
  }

  public static boolean exists(String URLName){
    try {
      HttpURLConnection.setFollowRedirects(false);
      // note : you may also need
      //        HttpURLConnection.setInstanceFollowRedirects(false)
      HttpURLConnection con =
         (HttpURLConnection) new URL(URLName).openConnection();
      con.setRequestMethod("HEAD");
      return (con.getResponseCode() == HttpURLConnection.HTTP_OK);
    }
    catch (Exception e) {
       e.printStackTrace();
       return false;
    }
  }
}
 
 
The following is doing the same thing but this time we identify ourself to a proxy.
See also this HowTo.
 
import java.net.*;
import java.io.*;
import java.util.Properties;

public class URLUtils {

  public static void main(String s[]) {
    System.out.println(exists("http://www.your_server.com"));
    System.out.println(exists("http://www.yahoo.com"));
  }


  public static boolean exists(String URLName){
    try {
      Properties systemSettings = System.getProperties();
      systemSettings.put("proxySet", "true");
      systemSettings.put("http.proxyHost","proxy.mycompany.local") ;
      systemSettings.put("http.proxyPort", "80") ;

      URL u = new URL(URLName);
      HttpURLConnection con = (HttpURLConnection) u.openConnection();
      //
      // it's not the greatest idea to use a sun.misc.* class
      // Sun strongly advises not to use them since they can 
      // change or go away in a future release so beware.
      //
      sun.misc.BASE64Encoder encoder = new sun.misc.BASE64Encoder();
      String encodedUserPwd =
         encoder.encode("domain\\username:password".getBytes());
      con.setRequestProperty
         ("Proxy-Authorization", "Basic " + encodedUserPwd);
      con.setRequestMethod("HEAD");
      System.out.println
         (con.getResponseCode() + " : " + con.getResponseMessage());
      return (con.getResponseCode() == HttpURLConnection.HTTP_OK);
    }
    catch (Exception e) {
      e.printStackTrace();
      return false;
    }
  }
}  

http://www.rgagnon.com/javadetails/java-0059.html