actionscript-3 - 在 AS3 中为垃圾收集器卸载对象

Question

我在 flex builder 中创建了一个名为 loginInterface 的对象。当这个对象被初始化时，它会加载登录界面，创建按钮，输入框等等。

我为这个对象创建了一个名为 unload 的方法。我还有一个方法可以返回界面是否已经加载。现在，我想卸载对象，以便屏幕不仅有空间用于新界面，而且还应该真正删除对象，以便可以重新分配内存。

loginInterface.as 类文件:

package
{
    //import required libraries
    import flash.display.Sprite;
    import flash.events.MouseEvent;
    import flash.net.URLRequest;
    import flash.net.navigateToURL;

    public class LoginInterface extends Sprite
    {
        private var welcomeLabel:CustomLabel;
        private var versionLabel:CustomLabel;
        private var loginButton:CustomButton;
        private var registerButton:CustomButton;
        private var usernameLabel:CustomLabel;
        private var passwordLabel:CustomLabel;
        private var usernameInputBox:CustomInputBox;
        private var passwordInputBox:CustomInputBox;
        private var loaded:Boolean = false;

        public function LoginInterface()
        {
            trace("LoginInterface object loaded.");
            init(); //initialize the login interface
        }

        public function init():void //initialize the login interface
        {
            trace("LoginInterface init method was called.");

            //create objects
            welcomeLabel = new CustomLabel(200, 100, 500, 30, "Welcome to the ALPHA client."); //welcome label
            versionLabel = new CustomLabel(200, 120, 500, 30, "Version: v1.0.000", "Arial", 0x000000, 12); //version label
            loginButton = new CustomButton(300, 300, 100, 30, "Login"); //login button
            registerButton = new CustomButton(400, 300, 100, 30, "Register") //register button          
            usernameLabel = new CustomLabel(200, 200, 200, 30, "username: "); //username label      
            passwordLabel = new CustomLabel(200, 240, 200, 30, "password: "); //password label
            usernameInputBox = new CustomInputBox(300, 200, 200, 30, false, 0x6D7B8D); //username input box
            passwordInputBox = new CustomInputBox(300, 240, 200, 30, true, 0x6D7B8D); //password input box

            //add objects to the display tree
            addChild(welcomeLabel);
            addChild(versionLabel);
            addChild(loginButton);
            addChild(registerButton);
            addChild(usernameInputBox);
            addChild(usernameLabel);
            addChild(passwordInputBox);
            addChild(passwordLabel);

            //register object events
            registerButton.addEventListener(MouseEvent.CLICK, registerClicked); //register button is clicked
            loginButton.addEventListener(MouseEvent.CLICK, loginClicked); //login button is clicked

            //interface has been loaded
            loaded = true;
        }

        public function isLoaded():Boolean
        {
            if (loaded) return true;
            return false;
        }

        public function unload():void
        {
            if (!loaded) return;
            //welcomeLabel
            removeChild(welcomeLabel);
            welcomeLabel = null;
            //versionLabel
            removeChild(versionLabel);
            versionLabel = null;
            //loginButton
            loginButton.removeEventListener(MouseEvent.CLICK, loginClicked);
            removeChild(loginButton);
            loginButton = null;
            //registerButton
            registerButton.removeEventListener(MouseEvent.CLICK, registerClicked);
            removeChild(registerButton);
            registerButton = null;
            //usernameInputBox
            removeChild(usernameInputBox);
            usernameInputBox = null;
            //usernameLabel
            removeChild(usernameLabel);
            usernameLabel = null;
            //passwordInputBox
            removeChild(passwordInputBox);
            passwordInputBox = null;
            //passwordLabel
            removeChild(passwordLabel);
            passwordLabel = null;
            //set loaded to false
            loaded = false;
        }

        private function loginClicked(event:MouseEvent):void
        {
            trace("Login button has been clicked.");
            var username:String = usernameInputBox.text;
            var password:String = passwordInputBox.text;
            if (!checkLogin(username, password)) {
                new Alert("Please enter a correct username and password.");
            }
            else {
                trace("Creating socket connection.");
                var socketConnection:SocketConnection = new SocketConnection(this);
            }
        }

        private function checkLogin(username:String, password:String):Boolean
        {
            if ((username == "") || (password == "")) {
                return false;
            }
            return true;
        }

        private function registerClicked(event:MouseEvent):void
        {
            trace("Register button has been clicked.");
            var url:URLRequest = new URLRequest("http://url.com/client/register.php");
            navigateToURL(url, "_blank");
        }
    }
}

请参阅加载对象的 init 函数和应卸载对象的 unload 函数。这在视觉上是有效的。然而，这是最好的方法吗？它甚至会在一段时间后让垃圾收集器从内存中卸载这些对象吗？

Answer 1

当您从其父对象的 displayList 中删除一个对象(例如 LoginInterface)时，该对象内的所有子对象也将自动从内存中删除，只要没有其他对象包含对子对象的引用。

因此，您实际上不需要删除添加到 LoginInterface 的 displayList 中的每个对象。您只需要删除您分配的事件监听器。

所以，你所做的并没有错，但你真正需要的只是你的unload。方法是:

loginButton.removeEventListener(MouseEvent.CLICK, loginClicked);
registerButton.removeEventListener(MouseEvent.CLICK, registerClicked);

希望有帮助。