隐式启动判断是否有匹配的Intent

一、PackageManager的resolveActivity

  public abstract ResolveInfo resolveActivity(Intent intent, int flags);

getPackageManager().resolveActivity（）;

返回能够匹配的Intent，如果不能匹配就返回NULL，

二、PackageManager的queryIntentActivities

public abstract List<ResolveInfo> queryIntentActivities(Intent intent,
        int flags);

getPackageManager().queryIntentActivities(intent,PackageManager.MATCH_DEFAULT_ONLY);

返回所有成功匹配的Activity信息

三、Intent的resolveActivity

 public ComponentName resolveActivity(PackageManager pm)

Intent intent = new Intent();
        ComponentName componentName = intent.resolveActivity();

第一个参数代表Intent

第二个参数：设置PackageManager.MATCH_DEFAULT_ONLY