从AndroidManifest.xml中获取已注册Activity的方法

契机：

在学习并积累自定义控件，为了看效果，需要放到Activity中来显示。

每次写新的自定义控件，不可能都放到同一个Activity中，为了更好观看效果，每个Activity中只放少数控件。

如此，随着自定义控件增多，Activity也逐渐增多，相应的需要在AndroidManifest中配置，还需要想办法（例如写个按钮）能够访问每个Activity。

于是，有没有办法自动从AndroidManifest.xml中获取所有已经注册过的Activity，放到ListView中显示呢。

写了以下工具类:

public final class ClassUtils {
private final static String TAG = "ClassUtils";
private ClassUtils(){}

/**
* 返回AndroidManifest.xml中注册的所有Activity的class
* @param context                环境
* @param packageName  		包名
* @param excludeList        排除class列表
* @return
*/
public final static List<Class> getActivitiesClass(Context context, String packageName, List<Class> excludeList){

List<Class> returnClassList = new ArrayList<Class>();
try {
//Get all activity classes in the AndroidManifest.xml
PackageInfo packageInfo = context.getPackageManager().getPackageInfo(packageName, PackageManager.GET_ACTIVITIES);
if(packageInfo.activities!=null){
Log.d(TAG, "Found "+packageInfo.activities.length +" activity in the AndrodiManifest.xml");
for(ActivityInfo ai: packageInfo.activities){
Class c;
try {
c = Class.forName(ai.name);
// Maybe isAssignableFrom is unnecessary
if(Activity.class.isAssignableFrom(c)){
returnClassList.add(c);
Log.d(TAG, ai.name +"...OK");
}
} catch (ClassNotFoundException e) {
Log.d(TAG, "Class Not Found:"+ai.name);
//                                                e.printStackTrace();
}
}
Log.d(TAG, "Filter out, left "+ returnClassList.size()  +" activity," + Arrays.toString(returnClassList.toArray()));

//Exclude some activity classes
if(excludeList!=null){
returnClassList.removeAll(excludeList);
Log.d(TAG, "Exclude " + excludeList.size() +" activity,"+ Arrays.toString(excludeList.toArray()));
}
Log.d(TAG, "Return "+ returnClassList.size()  +" activity," + Arrays.toString(returnClassList.toArray()));
}
} catch (NameNotFoundException e) {
e.printStackTrace();
}

return returnClassList;
}

}

调用：

List<Class> excludeList = new ArrayList<Class>();
excludeList.add(this.getClass());
List<Class> activities = ClassUtils.getActivitiesClass(this, getPackageName(), excludeList);

activities作为数据源与ListView绑定在一起，点击的时候跳转

startActivity(new Intent(MainActivity.this, activities.get(position)));