private void go2App(String packageName) {

        if (!isAppInstalled(this, packageName)) {

            ToastUtil.showToast(this, "您没有安装此应用", Toast.LENGTH_LONG);

            return;

        }

        String mainAct = null;

        Intent intent = new Intent(Intent.ACTION_MAIN);

        intent.addCategory(Intent.CATEGORY_LAUNCHER);

        PackageManager manager = this.getPackageManager();

        List<ResolveInfo> list = manager.queryIntentActivities(intent, PackageManager.GET_ACTIVITIES);

        for (int i = 0; i < list.size(); i++) {

            ResolveInfo info = list.get(i);

            if (info.activityInfo.packageName.equals(packageName)) {

                mainAct = info.activityInfo.name;

                break;

            }

        }

        if (TextUtils.isEmpty(mainAct)) {

            ToastUtil.showToast(this, "打开失败", Toast.LENGTH_LONG);

        }

//        intent.setComponent(new ComponentName(packageName, mainAct));//也可以使用这种方式

        intent.setClassName(packageName, mainAct);

        startActivity(intent);

    }

    /*

     * check the app is installed

     */

    private boolean isAppInstalled(Context context, String packagename) {

        PackageInfo packageInfo;

        try {

            packageInfo = context.getPackageManager().getPackageInfo(packagename, 0);

        } catch (NameNotFoundException e) {

            packageInfo = null;

            e.printStackTrace();

        }

        if (packageInfo == null) {

            // System.out.println("没有安装");

            return false;

        } else {

            // System.out.println("已经安装");

            return true;

        }

    }

    private void go2Browser(String url) {

        if (!isAppInstalled(this, "com.tencent.mtt")) {

            ToastUtil.showToast(this, "您没有安装QQ浏览器", Toast.LENGTH_LONG);

            return;

        }

        Uri uri = Uri.parse(url);

        Intent intent = new Intent();

        intent.setAction("android.intent.action.VIEW");

        intent.setClassName("com.tencent.mtt", "com.tencent.mtt.MainActivity");

        intent.setData(uri);

        startActivity(intent);

    }