前提是第三方apk的AndroidManifest的某個activity中的export = "true"   

/**
     *
     * 開啟另一個app
     * @param packageName
     * @param className
     */
    public void goToAnotherApp(String packageName,String className){
        Intent intent = new Intent();
        if(isAvilible(Main2Activity.this,packageName)){
            intent.setAction(Intent.ACTION_MAIN);
            //前提：知道要跳轉應用的包名、類名
            ComponentName componentName = new ComponentName(packageName, className);
            intent.setComponent(componentName);
            startActivity(intent);
        }else{
            Toast.makeText(Main2Activity.this, "沒有該應用", Toast.LENGTH_SHORT).show();
        }

    }

    /**
     * 判斷相對應的APP是否存在
     *
     * @param context
     * @param packageName(包名)(若想判斷QQ，則改為com.tencent.mobileqq，若想判斷微信，則改為com.tencent.mm)
     * @return
     */
    public boolean isAvilible(Context context, String packageName) {
        PackageManager packageManager = context.getPackageManager();

        //獲取手機系統的所有APP包名，然後進行一一比較
        List<PackageInfo> pinfo = packageManager.getInstalledPackages(0);
        for (int i = 0; i < pinfo.size(); i++) {
            if (((PackageInfo) pinfo.get(i)).packageName
                    .equalsIgnoreCase(packageName))
                return true;
        }
        return false;
    }

    /**
     * 通過已知apk獲取到該app的包名
     */
    private void getPackageNameByApk() {
        String FilePath = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "xinga.apk";//輸入APK地址
        PackageManager pm = getPackageManager();
        PackageInfo info = pm.getPackageArchiveInfo(FilePath, PackageManager.GET_ACTIVITIES);
        if (info != null) {
            ApplicationInfo appInfo = info.applicationInfo;
            String appName = pm.getApplicationLabel(appInfo).toString();
            String packageName = appInfo.packageName;  //獲取安裝包名稱
//            com.travelsky.mrt.oneetrip
//            com.travelsky.mrt.oneetrip.common.WelcomeActivity
            Log.i("Abel_Test", "包名是：" + packageName);
            String version = info.versionName; //獲取版本資訊
            Log.i("Abel_Tes", "版本資訊：" + version);
        }
    }


    /**
     * 通過包名獲取app詳細資訊
     * @param packagename
     */
    private void doStartApplicationWithPackageName(String packagename) {
        // 通過包名獲取此APP詳細資訊，包括Activities、services、versioncode、name等等
        PackageInfo packageinfo = null;
        try {
            packageinfo = getPackageManager().getPackageInfo(packagename, 0);
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }
        if (packageinfo == null) {
            return;
        }

        // 建立一個類別為CATEGORY_LAUNCHER的該包名的Intent
        Intent resolveIntent = new Intent(Intent.ACTION_MAIN, null);
        resolveIntent.addCategory(Intent.CATEGORY_LAUNCHER);
        resolveIntent.setPackage(packageinfo.packageName);

        // 通過getPackageManager()的queryIntentActivities方法遍歷
        List<ResolveInfo> resolveinfoList = getPackageManager()
                .queryIntentActivities(resolveIntent, 0);

        ResolveInfo resolveinfo = resolveinfoList.iterator().next();
        if (resolveinfo != null) {
            // packagename = 引數packname
            String packageName = resolveinfo.activityInfo.packageName;
            // 這個就是我們要找的該APP的LAUNCHER的Activity[組織形式：packagename.mainActivityname]
            String className = resolveinfo.activityInfo.name;
            Log.i("Abel_Tes", "版本資訊：" + className);
            // LAUNCHER Intent
            Intent intent = new Intent(Intent.ACTION_MAIN);
            intent.addCategory(Intent.CATEGORY_LAUNCHER);

            // 設定ComponentName引數1:packagename引數2:MainActivity路徑
            ComponentName cn = new ComponentName(packageName, className);

            intent.setComponent(cn);
            startActivity(intent);
        }
    }