public File getFile(int index) throws IOException {
            synchronized (DiskLruCache.this) {
                if (entry.currentEditor != this) {
                    throw new IllegalStateException();
                }
                if (!entry.readable) {
                    written[index] = true;
                }
                File dirtyFile = entry.getDirtyFile(index);
                if (!directory.exists()) {
                    directory.mkdirs();
                }
                return dirtyFile;
            }
        }
A {@link ThreadFactory} that builds a thread with a specific thread name
and with minimum priority.
VideoSqlLite/src/main/java/com/yc/videosqllite/disk/DiskLruCache.java