如何限制 Java 中 JPasswordField 中的位数? [英] How to limit the number of digits in a JPasswordField in Java?
问题描述
我的 Java 代码在 Eclipse 中运行，但我需要添加一些功能.
I have my Java code working in Eclipse but I need to add a few functionnality.
首先，如何限制用户可以输入的位数?实际上我有一个 JPasswordField 可以让一个人输入密码，我希望这个 JPasswordField 最多限制为 4 位数字.那么如何在输入 4 位后立即停止输入呢?
First, how to limit the number of digits that can be entered by the user ? Actually I have a JPasswordField that let a person enter a pin Code, and I would like this JPasswordField limited to 4 digits maximum. So how to stop the input as soon as 4 digits are entered ?
那么，我该如何使用 JPassword 框的大小呢?有没有办法像 JTextField 一样修改它?因为我的行p1.setPreferredSize(new Dimension(100, 25));"似乎并没有真正让我修改框的大小.
Then, how can I play with the size of the JPassword box ? Is there a way to modify it just like a JTextField for example ? Because my line "p1.setPreferredSize(new Dimension(100, 25));" does not seem to really let me modify the size of the box.
如您所见，JPassworldField 框有一个默认大小，我不知道如何轻松修改.
As you can see, the JPassworldField box has a default size that I can not figure out how to modify easily.
这是我的代码:
package codePin;
import java.io.*;
import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Main extends JFrame {
private static final long serialVersionUID = 1L;
private JPanel container = new JPanel();
private JPasswordField p1 = new JPasswordField(4);
private JLabel label = new JLabel("Enter Pin: ");
private JButton b = new JButton("OK");
public Main() {
this.setTitle("NEEDS");
this.setSize(300, 500);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
container.setBackground(Color.white);
container.setLayout(new BorderLayout());
JPanel top = new JPanel();
p1.setPreferredSize(new Dimension(100, 25)); //How to really modifiy this ?
b.addActionListener(new BoutonListener());
top.add(label);
top.add(p1);
p1.setEchoChar('*');
top.add(b);
this.setContentPane(top);
this.setVisible(true);
}
class BoutonListener implements ActionListener {
private final AtomicInteger nbTry = new AtomicInteger(0);
@SuppressWarnings("deprecation")
public void actionPerformed(ActionEvent e) {
if (nbTry.get() > 2) {
JOptionPane.showMessageDialog(null,
"Pin blocked due to 3 wrong tries");
return;
}
if (p1.getText().replaceAll("u00A0", "").length() != 4) {
// System.out.println("Pin must be 4 digits");
JOptionPane.showMessageDialog(null, "Ping must be 4 digits");
return;
}
System.out.println("Checking...");
SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>() {
@Override
protected Void doInBackground() throws Exception {
boolean authenticated = false;
ArrayList<Integer> pins = new ArrayList<Integer>();
readPinsData(new File("bdd.txt"), pins);
String[] thePins = new String[pins.size()];
for (int i = 0; i < thePins.length; i++) {
thePins[i] = pins.get(i).toString();
}
String passEntered = String.valueOf(p1);
for (String thePin : thePins) {
if (passEntered.equals(thePin)
&& p1.getText().length() == 4) {
System.out.println(":)");
authenticated = true;
break;
}
}
if (!authenticated) {
System.out.println(":(");
nbTry.incrementAndGet();
}
return null;
}
};
worker.execute();
}
}
// Accessing pins Bdd file
static public boolean readPinsData(File dataFile, ArrayList<Integer> data) {
boolean err = false;
try {
Scanner scanner = new Scanner(dataFile);
String line;
while (scanner.hasNext()) {
line = scanner.nextLine();
try {
data.add(Integer.parseInt(line));
} catch (NumberFormatException e) {
e.printStackTrace();
err = true;
}
}
scanner.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
err = true;
}
return err;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new Main();
}
});
}
}
有什么想法吗?谢谢.
弗洛伦特
这是我用 nachokk 的解决方案编辑的代码:
Here is my code edited with nachokk's solution :
import java.io.*;
import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;
import javax.swing.*;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
import javax.swing.text.PlainDocument;
import java.awt.*;
import java.awt.event.*;
public class Main extends JFrame {
private static final long serialVersionUID = 1L;
private JPanel container = new JPanel();
private JPasswordField p1 = new JPasswordField(4);
private JLabel label = new JLabel("Enter Pin: ");
private JButton b = new JButton("OK");
public Main() {
this.setTitle("NEEDS");
this.setSize(300, 500);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLocationRelativeTo(null);
container.setBackground(Color.white);
container.setLayout(new BorderLayout());
JPanel top = new JPanel();
PlainDocument document =(PlainDocument)p1.getDocument();
b.addActionListener(new BoutonListener());
top.add(label);
top.add(p1);
p1.setEchoChar('*');
top.add(b);
this.setContentPane(top);
this.setVisible(true);
document.setDocumentFilter(new DocumentFilter(){
@Override
public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException {
String string =fb.getDocument().getText(0, fb.getDocument().getLength())+text;
if(string.length() <= 4)
super.replace(fb, offset, length, text, attrs); //To change body of generated methods, choose Tools | Templates.
}
});
container.add(p1);
}
class BoutonListener implements ActionListener {
private final AtomicInteger nbTry = new AtomicInteger(0);
@SuppressWarnings("deprecation")
public void actionPerformed(ActionEvent e) {
if (nbTry.get() > 2) {
JOptionPane.showMessageDialog(null,
"Pin blocked due to 3 wrong tries");
return;
}
if (p1.getText().replaceAll("u00A0", "").length() != 4) {
// System.out.println("Pin must be 4 digits");
JOptionPane.showMessageDialog(null, "Ping must be 4 digits");
return;
}
System.out.println("Checking...");
SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>() {
@Override
protected Void doInBackground() throws Exception {
boolean authenticated = false;
ArrayList<Integer> pins = new ArrayList<Integer>();
readPinsData(new File("bdd.txt"), pins);
String[] thePins = new String[pins.size()];
for (int i = 0; i < thePins.length; i++) {
thePins[i] = pins.get(i).toString();
}
String passEntered = String.valueOf(p1);
for (String thePin : thePins) {
if (passEntered.equals(thePin)
&& p1.getText().length() == 4) {
System.out.println(":)");
authenticated = true;
break;
}
}
if (!authenticated) {
System.out.println(":(");
nbTry.incrementAndGet();
}
return null;
}
};
worker.execute();
}
}
// Fonction permettant d'accéder/lire notre BDD de pins (fichier .txt)
static public boolean readPinsData(File dataFile, ArrayList<Integer> data) {
boolean err = false;
try {
Scanner scanner = new Scanner(dataFile);
String line;
while (scanner.hasNext()) {
line = scanner.nextLine();
try {
data.add(Integer.parseInt(line));
} catch (NumberFormatException e) {
e.printStackTrace();
err = true;
}
}
scanner.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
err = true;
}
return err;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new Main();
}
});
}
}
推荐答案
如何使用 JPassword 框的大小?有没有办法例如像 JTextField 一样修改它?因为我的线p1.setPreferredSize(新维度(100, 25));"似乎不是真的让我修改框的大小.
How can I play with the size of the JPassword box ? Is there a way to modify it just like a JTextField for example ? Because my line "p1.setPreferredSize(new Dimension(100, 25));" does not seem to really let me modify the size of the box.
不要使用 setPrefferedSize() 而是使用此构造函数 JPasswordField(int col).阅读更多关于这里 我应该避免在 Java Swing 中使用 set(Preferred|Maximum|Minimum)Size 方法?
如何限制可以输入的位数用户?实际上我有一个 JPasswordField 可以让一个人输入密码代码，我希望这个 JPasswordField 限制为 4 位最大限度.那么如何在输入 4 位后立即停止输入呢?
How to limit the number of digits that can be entered by the user ? Actually I have a JPasswordField that let a person enter a pin Code, and I would like this JPasswordField limited to 4 digits maximum. So how to stop the input as soon as 4 digits are entered ?
对于限制输入，您可以使用 DocumentFilter，如下例所示.
For limit input you can use DocumentFilter as shown in example below.
public class JPasswordFieldTest {
private JPanel panel;
public JPasswordFieldTest() {
panel = new JPanel();
//set horizontal gap
((FlowLayout) panel.getLayout()).setHgap(2);
panel.add(new JLabel("Enter pin :"));
JPasswordField passwordField = new JPasswordField(4);
PlainDocument document = (PlainDocument) passwordField.getDocument();
document.setDocumentFilter(new DocumentFilter() {
@Override
public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException {
String string = fb.getDocument().getText(0, fb.getDocument().getLength()) + text;
if (string.length() <= 4) {
super.replace(fb, offset, length, text, attrs); //To change body of generated methods, choose Tools | Templates.
}
}
});
panel.add(passwordField);
JButton button = new JButton("OK");
panel.add(button);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI("Password Example");
}
});
}
private static void createAndShowGUI(String str) {
JFrame frame = new JFrame(str);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
JPasswordFieldTest test = new JPasswordFieldTest();
frame.add(test.panel);
frame.pack();
frame.setVisible(true);
}
}
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