android 将Assets资源文件的图片等复制到sd卡中

这是   FileUtils   工具类的方法

private static String SD_DIR = Environment.getExternalStorageDirectory().getPath() + File.separator;

public static void copyAll(Context cxt) {
    File dir = new File(SD_DIR);
    copySelf(cxt,"alivc_resource");
    dir.mkdirs();
}

public static void copySelf(Context cxt, String root) {
    try {
        String[] files = cxt.getAssets().list(root);
        if(files != null && files.length > 0) {
            File subdir = new File(SD_DIR + root);
            if (!subdir.exists()) {
                subdir.mkdirs();
            }
            for (String fileName : files) {
                File file = new File(SD_DIR + root + File.separator + fileName);
                if (file.exists()&&!file.isDirectory()){
                    continue;
                }
                copySelf(cxt,root + "/" + fileName);
            }
        }else{
            OutputStream myOutput = new FileOutputStream(SD_DIR+root);
            InputStream myInput = cxt.getAssets().open(root);
            byte[] buffer = new byte[1024 * 8];
            int length = myInput.read(buffer);
            while(length > 0)
            {
                myOutput.write(buffer, 0, length);
                length = myInput.read(buffer);
            }

            myOutput.flush();
            myInput.close();
            myOutput.close();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

使用：可以放在application中执行

private AsyncTask copyTask=new AsyncTask() {
    @Override
    protected Object doInBackground(Object[] objects) {
        FileUtils.copyAll(getApplicationContext());
        return null;
    }
};

//复制asset中的资源到内存卡
copyTask.execute();