完成对JTextField的条形码扫描后执行操作 [英] Perform action upon completion of barcode scanning to JTextField
问题描述
我有一个JTextField barcodeTextField，它可以使用条形码扫描仪从扫描的条形码中接收字符.据我所知，条形码扫描就像非常快速地键入字符或将字符复制粘贴到文本字段上. barcodeTextField还用于显示建议并在其他字段中填充信息(就像在Google中搜索时一样，其中会在您键入内容时显示建议).
I have a JTextField barcodeTextField which accepts characters from the scanned barcode using a barcode scanner. From what I know, barcode scanning is like typing the characters very fast or copy-pasting the characters on the text field. barcodeTextField is also used to show suggestions and fill up others fields with information (just like searching in Google where suggestions are shown as you type).
到目前为止，我已使用DocumentListener实施了此操作:
So far I implemented this using DocumentListener:
barcodeTextField.getDocument().addDocumentListener(new DocumentListener() {
public void set() {
System.out.println("Pass");
// Do a lot of things here like DB CRUD operations.
}
@Override
public void removeUpdate(DocumentEvent arg0) {
set();
}
@Override
public void insertUpdate(DocumentEvent arg0) {
set();
}
@Override
public void changedUpdate(DocumentEvent arg0) {
set();
}
});
问题是:如果扫描的条形码包含13个字符，则set()将执行13次，以此类推.当我键入"123"以显示建议列表时，set()被执行3次.
The problem is: If the barcode scanned has 13 characters, set() is executed 13 times, and so with DB operations. Same goes when I type "123" to show suggestion list, set() is executed 3 times.
我希望set()在用户停止在barcodeTextField上键入时得到执行.在Javascript/JQuery中，可以使用keyup()事件并在用户仍在键入时在内部包含setTimeout()方法(clearTimeout())来完成此操作.
I wanted set() to get executed when the user stops typing on barcodeTextField. In Javascript/JQuery, this can be done using the keyup() event and having setTimeout() method inside, clearTimeout() when user is still typing.
如何在Java中为JTextField实施此行为?
How to implement this behavior for JTextField in Java?
推荐答案
当用户停止键入时，有什么方法可以获取在JTextField上输入的字符串"
"Is there any way to obtain the string entered on JTextField when the user stops typing"
以同样的方式，Javascript具有超时，Swing具有Timer.因此，如果您在Javscript中使用其计时器"功能实现了所需的功能，则可以查看是否可以使用
The same way, Javascript has the timeout, Swing has a Timer. So if what you are looking for is achieved in Javscript using its "timer" fucntionality, you can see if you can get it working with a Swing Timers
例如 Timer 具有 restart .因此，您可以在计时器上设置一个1000毫秒的延迟.键入文本后(文档中的第一次更改)，请检查 if (timer.isRunning()) ，如果是timer.restart()，则为timer.start()，否则为timer.start()(表示文档中的首次更改).仅当在任何文档更改后经过一秒钟时，计时器的操作才会发生.在秒表计时结束之前发生的任何进一步变化都会使定时器复位.并将timer.setRepeats(false)设置为仅执行一次操作
For example Timer has a restart. So you can set a delay on the timer for say 1000 milliseconds. Once text is being typed (first change in the document), check if (timer.isRunning()), and timer.restart() if it is, else timer.start() (meaning first change in document). The action for the timer will only occur if one second passes after any document change. Any further changes occurring before the second is up, will cause the timer to reset. And set timer.setRepeats(false) so the action only occurs once
您的文档侦听器可能看起来像
Your document listener might look something like
class TimerDocumentListener implements DocumentListener {
private Document doc;
private Timer timer;
public TimerDocumentListener() {
timer = new Timer(1000, new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (doc != null) {
try {
String text = doc.getText(0, doc.getLength());
statusLabel.setText(text);
} catch (BadLocationException ex) {
Logger.getLogger(TimerDemo.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
});
timer.setRepeats(false);
}
public void insertUpdate(DocumentEvent e) { set(e); }
public void removeUpdate(DocumentEvent e) { set(e); }
public void changedUpdate(DocumentEvent e) { set(e); }
private void set(DocumentEvent e) {
if (timer.isRunning()) {
timer.restart();
} else {
this.doc = e.getDocument();
timer.start();
}
}
}
这是一个完整的示例，其中我以500毫秒的受控间隔显式插入文本字段的文档(九个数字)中，以模拟"键入内容.您可以在DocumentListener拥有的Timer中看到延迟为1000毫秒.因此，只要发生键入，由于延迟时间超过500毫秒，DocumentListener计时器将不会执行其操作.对于文档中的每个更改，计时器都会重新启动.
Here's a complete example, where I "mock" typing, by explicitly inserting into the document (nine numbers) of the text field at a controlled interval of 500 milliseconds. You can see in the Timer owned by the DocumentListener that the delay is 1000 milliseconds. So as long as the typing occurs, the DocumentListener timer will not perform its action as the delay is longer than 500 milliseconds. For every change in the document, the timer restarts.
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
public class TimerDemo {
private JTextField field;
private JLabel statusLabel;
public static void main(String[] args) {
Runnable runnable = new Runnable() {
public void run() {
new TimerDemo();
}
};
SwingUtilities.invokeLater(runnable);
}
public TimerDemo() {
JFrame frame = new JFrame();
frame.setLayout(new GridLayout(0, 1));
field = new JTextField(20);
field.getDocument().addDocumentListener(new TimerDocumentListener());
statusLabel = new JLabel(" ");
JButton start = new JButton("Start Fake Typing");
start.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
startInsertTimer();
}
});
frame.add(field);
frame.add(statusLabel);
frame.add(start);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private void startInsertTimer() {
Timer timer = new Timer(500, new ActionListener() {
private int count = 9;
public void actionPerformed(ActionEvent e) {
if (count == 0) {
((Timer) e.getSource()).stop();
} else {
Document doc = field.getDocument();
int length = doc.getLength();
try {
doc.insertString(length, Integer.toString(count), null);
} catch (BadLocationException ex) {
Logger.getLogger(TimerDemo.class.getName()).log(Level.SEVERE, null, ex);
}
count--;
}
}
});
timer.start();
}
class TimerDocumentListener implements DocumentListener {
private Document doc;
private Timer timer;
public TimerDocumentListener() {
timer = new Timer(1000, new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (doc != null) {
try {
String text = doc.getText(0, doc.getLength());
statusLabel.setText(text);
} catch (BadLocationException ex) {
Logger.getLogger(TimerDemo.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
});
timer.setRepeats(false);
}
public void insertUpdate(DocumentEvent e) { set(e); }
public void removeUpdate(DocumentEvent e) { set(e); }
public void changedUpdate(DocumentEvent e) { set(e); }
private void set(DocumentEvent e) {
if (timer.isRunning()) {
timer.restart();
} else {
this.doc = e.getDocument();
timer.start();
}
}
}
}
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