android通过包名跳转到系统闹钟

主要是通过包名来跳转系统的闹钟

这个在部分手机不可以跳转，

  //跳转系统闹钟
//                Intent alarmas = new Intent(AlarmClock.ACTION_SET_ALARM);
//                startActivity(alarmas);

所以要使用通过包名来调用系统闹钟

public class SystemClockDemoActivity extends Activity {
	Map<String, Object> item;
	private ArrayList<String> pagList;
	private Button button;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		button = (Button) findViewById(R.id.button);

		pagList = new ArrayList<String>();

		button.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View v) {
				listPackages();
				Log.d("mxt", "paglist的大小：" + pagList.size());
				for (int i = 0; i < pagList.size(); i++) {
					Log.d("mxt", pagList.get(i));
				}

				PackageManager pm = getPackageManager();

				Intent i = pm.getLaunchIntentForPackage(pagList.get(0));
				// 如果该程序不可启动（像系统自带的包，有很多是没有入口的）会返回NULL
				if (i != null) {
					SystemClockDemoActivity.this.startActivity(i);
				} else {
					Intent i2 = new Intent(Settings.ACTION_DATE_SETTINGS);
					SystemClockDemoActivity.this.startActivity(i);
				}

			}
		});

	}

	class PInfo {
		private String appname = "";
		private String pname = "";
		private String versionName = "";
		private int versionCode = 0;
		private Drawable icon;

		private void prettyPrint() {
			Log.i("taskmanger", appname + "\t" + pname + "\t" + versionName
					+ "\t" + versionCode + "\t");
		}
	}

	private void listPackages() {
		ArrayList<PInfo> apps = getInstalledApps(false); /*
														 * false = no system
														 * packages
														 */
		final int max = apps.size();
		for (int i = 0; i < max; i++) {
			apps.get(i).prettyPrint();
			item = new HashMap<String, Object>();

			int aa = apps.get(i).pname.length();
			if (aa > 11) {
				if (apps.get(i).pname.indexOf("clock") != -1) {
					if (!(apps.get(i).pname.indexOf("widget") != -1)) {
						try {
							PackageInfo pInfo = getPackageManager()
									.getPackageInfo(apps.get(i).pname, 0);
							if (isSystemApp(pInfo) || isSystemUpdateApp(pInfo)) {
								Log.d("mxt", "是系统自带的");
								Log.d("mxt",
										"找到了"
												+ apps.get(i).pname
														.substring(apps.get(i).pname
																.length() - 5)
												+ "  全名：" + apps.get(i).pname
												+ " " + apps.get(i).appname);
								item.put("pname", apps.get(i).pname);
								item.put("appname", apps.get(i).appname);
								pagList.add(apps.get(i).pname);
							}
						} catch (Exception e) {
							// TODO: handle exception
						}

					}
				}
			}

		}
	}

	private ArrayList<PInfo> getInstalledApps(boolean getSysPackages) {
		ArrayList<PInfo> res = new ArrayList<PInfo>();
		List<PackageInfo> packs = getPackageManager().getInstalledPackages(0);
		for (int i = 0; i < packs.size(); i++) {
			PackageInfo p = packs.get(i);
			if ((!getSysPackages) && (p.versionName == null)) {
				continue;
			}
			PInfo newInfo = new PInfo();
			newInfo.appname = p.applicationInfo.loadLabel(getPackageManager())
					.toString();
			newInfo.pname = p.packageName;
			newInfo.versionName = p.versionName;
			newInfo.versionCode = p.versionCode;
			newInfo.icon = p.applicationInfo.loadIcon(getPackageManager());
			res.add(newInfo);
		}
		return res;
	}

	public boolean isSystemApp(PackageInfo pInfo) {
		return ((pInfo.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0);
	}

	public boolean isSystemUpdateApp(PackageInfo pInfo) {
		return ((pInfo.applicationInfo.flags & ApplicationInfo.FLAG_UPDATED_SYSTEM_APP) != 0);
	}
}