启动APK的默认Activity

public static void startApkActivity(final Context ctx, String packageName) {
    PackageManager pm = ctx.getPackageManager();
    PackageInfo pi;
    try {
        pi = pm.getPackageInfo(packageName, 0);
        Intent intent = new Intent(Intent.ACTION_MAIN, null);
        intent.addCategory(Intent.CATEGORY_LAUNCHER);
        intent.setPackage(pi.packageName);

        List<ResolveInfo> apps = pm.queryIntentActivities(intent, 0);

        ResolveInfo ri = apps.iterator().next();
        if (ri != null) {
            String className = ri.activityInfo.name;
            intent.setComponent(new ComponentName(packageName, className));
            ctx.startActivity(intent);
        }
    } catch (NameNotFoundException e) {
        Log.e("startActivity", e);
    }
}