String DB_PATH = "/data/data/com.example.loldate/databases/";
        String DB_NAME = "loldata.db";     //数据库路径及名称

        if ((new File(DB_PATH + DB_NAME).exists() == false)) {
            File f = new File(DB_PATH);
            if (!f.exists()) {
                f.mkdir();
            }

        };// 检查数据库路径文件夹是否存在，不存在的话就建立
        try {
            InputStream is = getBaseContext().getAssets().open(DB_NAME);
            OutputStream os = new FileOutputStream(DB_PATH + DB_NAME);
            byte[] buffer = new byte[1024 * 10];
            int length;
            while ((length = is.read(buffer)) > 0) {
                os.write(buffer, 0, length);
            }
            os.flush();
            os.close();
            is.close();

        } catch (Exception e) {
            e.printStackTrace();
        }  //  将assets中的数据库文件复制到手机中