ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);

ComponentName cn = am.getRunningTasks(1).get(0).topActivity;

String currentPackageName = cn.getPackageName();

在4.4和5.0系統上沒有出現任何問題，但是在6.0上在跳轉的時候，一直報錯，讓activity 走onresume方法，解決辦法是直接去掉不使用這兩行程式碼，即可解決！

/***

*跳轉方法（來自網路，驗證可用）

*/

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 = mActivity.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 = mActivity.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;
// 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);
mActivity.startActivity(intent);
}
}