为了减少搜索时服务器的过载,我将提供键盘输入延迟。
用例:
1.用户输入符号
2.如果输入符号之间有延迟<1秒,则搜索不会立即执行,并在最后输入符号后的延迟为时等待> 1秒
3.如果输入符号之间的延迟>1秒,则搜索立即执行
JSE 或移动 Java(Blackberry)是否有最佳实践?
最佳答案
根据Java并发圣经'Java concurrency in practice '
... Timer has some drawbacks, and ScheduledThreadPoolExecutor should be thought of as its replacement.
因此,我会做类似这个例子的事情:
public class DelayedSearch extends JFrame {
public DelayedSearch() {
final JPanel panel = new JPanel(new BorderLayout());
final JTextField field = new JTextField(30);
panel.add(field, BorderLayout.NORTH);
final JLabel status = new JLabel(" ");
panel.add(status, BorderLayout.SOUTH);
this.add(panel);
this.pack();
final ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
field.addKeyListener(new KeyAdapter() {
private ScheduledFuture<?> scheduled;
@Override
public void keyTyped(KeyEvent e) {
if (scheduled != null) scheduled.cancel(false);
scheduled = executor.schedule(new Runnable() {
@Override
public void run() { // Perform search here. Just set status for demo.
status.setText("Search: " + field.getText());
}
}, 1, TimeUnit.SECONDS);
}
});
}
public static void main(String[] args) {
new DelayedSearch().setVisible(true);
}
}
注意:我正在从 EDT 以外的线程更新状态,这是非法的,但您明白了。
编辑:基于下面的精彩评论(谢谢!)Timer
将在这个简单的情况下工作,并且它使得使用守护线程变得容易(尽管它确实存在抛出异常的任务问题) ,如书中所述)。为此,请替换上面的执行器和监听器,如下所示:
...
final Timer timer = new Timer(true); // use daemon thread.
field.addKeyListener(new KeyAdapter() {
private TimerTask task;
@Override
public void keyTyped(KeyEvent e) {
if(task != null)task.cancel();
task = new TimerTask() {
@Override
public void run() {
status.setText("Search: " + field.getText());
}
};
timer.schedule(task, 1000);
}
});
关于java - 键盘输入: perform request with delay between symbols,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10163425/