tailieunhanh - JDK 1.1 AWT Event Handling

Syndication of micronews, frequently-updated content on the Web, is currently accomplished with RSS feeds and client applications that poll those feeds. However, providers of RSS content have recently become concerned about the escalating bandwidth demand of RSS readers. Current efforts to address this problem by optimizing the polling behavior of clients sacrifice timeliness without fun- damentally improving the scalability of the system. In this paper, we argue for a micronews distribution system called FeedTree, which uses a peer-to-peer overlay network to distribute RSS feed data to subscribers promptly and ef- ficiently. Peers in the network share the bandwidth costs, which reduces the load on the provider, and updated con- tent is delivered to. | JDK AWT Event Handling Object Computing Inc. 1 AWT Event Handling AWT Abstract Windowing Toolkit package - Easier to learn than Motif X and MFC Not as easy as using graphical GUI builders - several companies are creating them for Java - will output Java code that uses the AWT package AWT classes fall in four categories - components - containers - layout managers - event handling Object Computing Inc. 2 AWT Event Handling Steps To Use AWT Create a container - Frame Dialog Window Panel ScrollPane Select a LayoutManager - Flow Border Grid GridBag Card none null Create components - Button Checkbox Choice Label List TextArea TextField PopupMenu Add components to container Specify event handling changed in - listeners are objects interested in events - sources are objects that fire events - register listeners with sources EventType Listener - EventTypes are ActionEvent AdjustmentEvent ComponentEvent FocusEvent ItemEvent KeyEvent MouseEvent TextEvent WindowEvent - implement methods of listener interfaces in listener classes an event object is passed to the methods ActionListener AdjustmentListener ComponentListener FocusListener ItemListener KeyListener MouseListener MouseMotionListener TextListener WindowListener Object Computing Inc. 3 AWT Event .