java 监听器实现原理

灰太狼 2022-05-13 02:42 157阅读 0赞

1. 监听器实现者：

public class MyActivity extends Activity implements InternetManager.Listener {
    
        private TextView mText;
        private InternetManager mInetMgr;
    
        /* called just like onCreate at some point in time */ 
        public void onStateChange(boolean state) {
            if (state) {
                mText.setText("on");
            } else {
                mText.setText("off");
            }
        }
    
        public void onCreate() {
            mInetMgr = new InternetManager();
            mInetMgr.registerListener(this);
            mInetMgr.doYourWork();
        }
    }

自定义类，监听器作为内部属性(包含方法)，

类中存在调用监听器内部方法的地方，

set不同的监听器实现者，处理的方式便不一样，

监听器相当于一个钩子，做回调使用。

public class InternetManager {
        // all the listener stuff below
        public interface Listener {
            public void onStateChange(boolean state);
        }
    
        private Listener mListener = null;
        public void registerListener (Listener listener) {
            mListener = listener;
        }
    
        // -----------------------------
        // the part that this class does
    
        private boolean isInternetOn = false;
        public void doYourWork() {
            // do things here
            // at some point
            isInternetOn = true;
            // now notify if someone is interested.
            if (mListener != null)
                mListener.onStateChange(isInternetOn);
        }
    }

转载地址： [http://www.cnblogs.com/lotusve/archive/2012/07/02/2573628.html][http_www.cnblogs.com_lotusve_archive_2012_07_02_2573628.html]

[http_www.cnblogs.com_lotusve_archive_2012_07_02_2573628.html]: http://www.cnblogs.com/lotusve/archive/2012/07/02/2573628.html