如何限制Java中JPasswordField的位数？
hac*_*ife 2 java security passwords swing limit
我的Java代码在Eclipse中工作,但我需要添加一些功能.
首先,如何限制用户可以输入的位数？实际上我有一个JPasswordField让一个人输入一个pin代码,我希望这个JPasswordField最多限制为4位数.那么如何在输入4位数后立即停止输入？
然后,我如何玩JPassword框的大小？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盒子的大小.
如您所见,JPassworldField框具有默认大小,我无法弄清楚如何轻松修改.
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();
}
});
}
}
有任何想法吗 ？谢谢.
弗洛朗
这是我用nachokk解决方案编辑的代码:
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();
}
});
}
}
如何使用JPassword框的大小？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盒子的大小.
不要setPrefferedSize()使用这个构造函数JPasswordField(int col)
.在这里阅读更多关于 我应该避免在Java Swing中使用set(Preferred | Maximum | Minimum)Size方法吗？
如何限制用户可以输入的位数？实际上我有一个JPasswordField让一个人输入一个pin代码,我希望这个JPasswordField最多限制为4位数.那么如何在输入4位数后立即停止输入？
对于限制输入,您可以使用DocumentFilter如下面的示例所示.
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);
}
}
