AvatarFetcher.java

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLConnection;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;


public class AvatarFetcher {
  protected CodeSwarmConfig cfg;
  public int size; 
  public AvatarFetcher(CodeSwarmConfig cfg) {
    this.cfg = cfg;
    size = cfg.getPositiveIntProperty("AvatarSize");
  }
  
  public String fetchUserImage(String username) {
    throw new RuntimeException("Override fetchUserImage in your Avatar Fetcher");
  }
  
  protected static String getFilename(String key){
    return "image_cache/" + key;
  }
  
  protected static boolean imageCached(String key) {
    return new File(getFilename(key)).exists();
  }
  
  protected static String getImage(String key, URL url) {
    String filename = getFilename(key);
    if (!imageCached(key)){
      boolean successful = fetchImage(filename, url); 
      if (!successful)
        return null;
    }
      
    return filename;
  }
  
  protected static boolean fetchImage(String filename, URL url) {
    try {
      new File("image_cache").mkdirs();
      URLConnection con = url.openConnection();
      InputStream input = con.getInputStream();
      FileOutputStream output = new FileOutputStream(filename);

      int length = con.getContentLength();
      if (length == -1){
        //read until exhausted
        while(true){
          int val = input.read();
          if (val == -1)
            break;
          output.write(input.read());
        }
      }
      else{
        //read length bytes
        for(int i = 0; i < length; i++)
          output.write(input.read());
      }

      output.close();
      input.close();
      return true;
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      return false;
    }
  }
  
  //these two methods taken from http://en.gravatar.com/site/implement/java
  private static String hex(byte[] array) {
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < array.length; ++i)
      sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(1,3));
    return sb.toString();
  }
  protected static String md5Hex (String message) {
    try {
      MessageDigest md = MessageDigest.getInstance("MD5");
      return hex (md.digest(message.getBytes("CP1252")));
    } catch (NoSuchAlgorithmException e) {
    } catch (UnsupportedEncodingException e) {
    }
    return null;
  }

}