Android Open Source - android-sdk Rest Cache

• Back to Development/sdk  ↑

From Project

Back to project page android-sdk.

License

The source code is released under:

MIT License

Java Source Code

package io.doorbell.android.manavo.rest;
/* w  ww.j a v  a  2s .  c  o m*/
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.List;

import org.apache.http.NameValuePair;

import android.content.Context;

public class RestCache {
  
  public static boolean exists(RestApi api) {
    String hash = RestCache.getRequestHash(api);
    if (hash == null) {
      return false;
    } else {
      File file = RestCache.getFile(api.activity, hash);
      return file.exists();
    }
  }
  
  public static String get(RestApi api) {
    String hash = RestCache.getRequestHash(api);
    if (hash == null) {
      return null;
    } else {
      File file = RestCache.getFile(api.activity, hash);
      
      BufferedReader r;
      try {
        r = new BufferedReader(new FileReader(file));
        StringBuilder total = new StringBuilder();
        String line;
        while ((line = r.readLine()) != null) {
            total.append(line);
        }
        r.close();

        return total.toString();
      } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
      
      return null;
    }
  }
  
  public static void save(RestApi api, String data) {
    String hash = RestCache.getRequestHash(api);
    
    if (hash != null) {
      File file = RestCache.getFile(api.activity, hash);
      BufferedWriter out;
      try {
        out = new BufferedWriter(new FileWriter(file), 1024);
        out.write(data);
        out.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  }
  
  public static void clear(Context c) {
        // clear all the cache files
        File cacheDir = c.getCacheDir();
        for (File cacheFile : cacheDir.listFiles()) {
          if (".".equals(cacheFile.getName()) || "..".equals(cacheFile.getName())) {
            continue;  // Ignore the self and parent aliases.
          }
          cacheFile.delete();
        }
  }
  
  private static File getFile(Context c, String hash) {
    String filename = RestCache.getFilename(c, hash);
    if (filename != null) {
      return new File(filename);
    } else {
      return null;
    }
  }
  
  private static String getFilename(Context c, String hash) {
    File dir = c.getCacheDir();
    
    if (dir.canWrite() == false) {
      return null;
    }
    
    String cachePath = dir.getAbsolutePath();
    
    return cachePath+"/"+hash;
  }
  
  private static String getRequestHash(RestApi api) {
    List<NameValuePair> params = api.getParameters();
    
    String query = api.endpoint;
    
    if (query == null) {
      return null;
    }
    
    NameValuePair p;
    
    for (int i=0; i<params.size(); i++) {
      p = params.get(i);
      
      query += URLEncoder.encode(p.getName())+"="+URLEncoder.encode(p.getValue())+"&";
    }
    
    // get rid of the last ampersand
    if (query.length() > 0) {
      query.substring(0, query.length()-1);
    }

    try {
      String hash = RestCache.SHA1(query);
      return hash;
    } catch (NoSuchAlgorithmException e) {
      e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    }
    
    return null;
  }
  
  private static String convertToHex(byte[] data) { 
        StringBuffer buf = new StringBuffer();
        for (int i = 0; i < data.length; i++) { 
            int halfbyte = (data[i] >>> 4) & 0x0F;
            int two_halfs = 0;
            do {
                if ((0 <= halfbyte) && (halfbyte <= 9)) 
                    buf.append((char) ('0' + halfbyte));
                else
                    buf.append((char) ('a' + (halfbyte - 10)));
                halfbyte = data[i] & 0x0F;
            } while(two_halfs++ < 1);
        }
        return buf.toString();
    } 

    public static String SHA1(String text) throws NoSuchAlgorithmException, UnsupportedEncodingException  { 
      MessageDigest md;
      md = MessageDigest.getInstance("SHA-1");
      byte[] sha1hash = new byte[40];
      md.update(text.getBytes("iso-8859-1"), 0, text.length());
      sha1hash = md.digest();
      return convertToHex(sha1hash);
    }
  
    public class CachePolicy {
      public static final int IGNORE_CACHE = 0;
      public static final int CACHE_THEN_NETWORK = 1;
      public static final int NETWORK_ONLY = 2;
      public static final int CACHE_ELSE_NETWORK = 3;
      public static final int UPDATE_CACHE = 4;
    }
}

Java Source Code List

• Back to Development/sdk  ↑