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);
            }
        }