android常用的Application类

public class MainApplication extends Application{
    /**
     * 全局的上下文
     */
    private static Context mContext;
    @Override
    public void onCreate() {
        super.onCreate();
        Log.e("MainApplication", "onCreate()");
        mContext = getApplicationContext();

    }

    public static Context getContext() {
        return mContext;
    }

    public static String getPackageName2() {

        return mContext.getPackageName();
    }
}