CacheUtils.java

public static class CacheUtils {

        public static boolean exists(Context context, String filename) {
            return new File(context.getCacheDir(), filename).exists();
        }

        public static void write(Context context, String filename, final byte[] content, final boolean append) {
            final File cache = new File(context.getCacheDir(), filename);

            try {
                FileOutputStream out = new FileOutputStream(cache, append);
                out.write(content);
                out.close();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
        }

        public static String read(Context context, String filename) {
            File cache = new File(context.getCacheDir(), filename);
            if (cache.exists()) {
                StringBuilder content = new StringBuilder();
                try {
                    BufferedReader reader = new BufferedReader(new FileReader(cache));
                    String line;
                    while ((line = reader.readLine()) != null) {
                        content.append(line);
                        content.append('\n');
                    }
                    reader.close();
                } catch (IOException ioe) {
                    ioe.printStackTrace();
                } finally {
                    return String.valueOf(content);
                }
            } else {
                return null;
            }
        }
    }