一般情况下安装APK

    private void installNormal() {
        LogUtils.log(TAG, LogUtils.getThreadName());
        setStatus(State.INSTALLING);
        String rootpath = Environment.getExternalStorageDirectory().getPath()
                + File.separator + Environment.DIRECTORY_DOWNLOADS + File.separator;
        Uri uri = Uri.fromFile(new File(rootpath + downloadFileName));
        LogUtils.log(TAG, LogUtils.getThreadName() + "uri = " + uri);
        Intent intent = new Intent();
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent.setAction(Intent.ACTION_VIEW);
        intent.setDataAndType(uri, "application/vnd.android.package-archive");
        mContext.startActivity(intent);

    }