我想用Java写一个key listener。无论 Java 应用程序是否具有焦点，它都应该跟踪所有的按键操作。这可能吗？
这是可能的，但需要一个利用 JNI 的实现，它并不总是可移植的。
Java System Hook 是一个这样的库，可以与 Windows 32 和 64 位一起使用。
我刚才用过类似的东西。看看Java System Hook。
它通过 JNI 跟踪全局按键（不仅仅是你的 Java 应用程序）。它对我来说快速而完美
KeyListener 以守护线程的形式启动，它不会使应用程序保持活动状态。您的程序中必须有另一个正在运行的非守护线程
例如：
GlobalKeyListener globalKeyListener = new GlobalKeyListener();
globalKeyListener.addKeyListener(listener);
while (true) {
Thread.sleep(1000);
}
不，Java 无法访问其活动窗口之外的击键。
为此，您必须结合使用 Java 和本机代码，使用 JNI 调用本机代码。在 Microsoft Windows 中，您应该查看
GetAsyncKeyState(key)很有可能，但不是使用标准 Java，你必须在本机级别与操作系统交互。
这里是 Windows 的主题，它使用 JNA 访问 Windows User32 API 中的 SetWindowsHookEx 函数。
不，如果 Java 不是活动的（聚焦的）窗口，它不会监听按键，所以你不能那样做。
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
/*
* keylogger.java
*
* Created on Mar 8, 2012, 8:12:20 AM
*/
package main;
import javax.swing.JOptionPane;
/**
*
* @author Lab-Admin
*/
public class keylogger extends javax.swing.JFrame {
/** Creates new form keylogger */
public keylogger() {
initComponents();
}
/** This method is called from within the constructor to
* initialize the form.
* WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">//GEN-BEGIN:initComponents
private void initComponents() {
jPanel1 = new javax.swing.JPanel();
jLabel1 = new javax.swing.JLabel();
jPanel2 = new javax.swing.JPanel();
jLabel2 = new javax.swing.JLabel();
jLabel3 = new javax.swing.JLabel();
userfield = new javax.swing.JTextField();
jLabel4 = new javax.swing.JLabel();
passfield = new javax.swing.JPasswordField();
btnlogin = new javax.swing.JButton();
btncancel = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Punk Academy PRoject");
setBackground(new java.awt.Color(255, 0, 0));
setFont(new java.awt.Font("Algerian", 1, 14)); // NOI18N
setForeground(new java.awt.Color(255, 153, 0));
jPanel1.setBackground(new java.awt.Color(255, 204, 0));
jLabel1.setBackground(new java.awt.Color(255, 0, 0));
jLabel1.setFont(new java.awt.Font("Algerian", 1, 24)); // NOI18N
jLabel1.setText("Punk Academy");
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(102, 102, 102)
.addComponent(jLabel1)
.addContainerGap(108, Short.MAX_VALUE))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(20, 20, 20)
.addComponent(jLabel1)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
jPanel2.setBackground(new java.awt.Color(255, 255, 255));
jLabel2.setIcon(new javax.swing.ImageIcon("D:\\COPRO OLAER\\enrollment system\\umbrellalast.gif")); // NOI18N
jLabel3.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
jLabel3.setText("username");
jLabel4.setFont(new java.awt.Font("Tahoma", 1, 12)); // NOI18N
jLabel4.setText("password");
btnlogin.setIcon(new javax.swing.ImageIcon("D:\\COPRO OLAER\\enrollment system\\Keys.gif")); // NOI18N
btnlogin.setText("Log in");
btnlogin.setDisabledIcon(new javax.swing.ImageIcon("D:\\COPRO OLAER\\enrollment system\\Keys.gif")); // NOI18N
btnlogin.setDisabledSelectedIcon(new javax.swing.ImageIcon("D:\\COPRO OLAER\\enrollment system\\Keys.gif")); // NOI18N
btnlogin.setIconTextGap(2);
btnlogin.setPressedIcon(new javax.swing.ImageIcon("D:\\COPRO OLAER\\enrollment system\\Keys.gif")); // NOI18N
btnlogin.setRolloverIcon(new javax.swing.ImageIcon("D:\\COPRO OLAER\\enrollment system\\Keys.gif")); // NOI18N
btnlogin.setRolloverSelectedIcon(new javax.swing.ImageIcon("D:\\COPRO OLAER\\enrollment system\\Keys.gif")); // NOI18N
btnlogin.setSelectedIcon(new javax.swing.ImageIcon("D:\\COPRO OLAER\\enrollment system\\Keys.gif")); // NOI18N
btnlogin.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnloginActionPerformed(evt);
}
});
btncancel.setIcon(new javax.swing.ImageIcon("D:\\COPRO OLAER\\enrollment system\\exit.png")); // NOI18N
btncancel.setText("Cancel");
btncancel.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btncancelActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel2))
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel2Layout.createSequentialGroup()
.addContainerGap(82, Short.MAX_VALUE)
.addComponent(btnlogin, javax.swing.GroupLayout.PREFERRED_SIZE, 104, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)))
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(16, 16, 16)
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel3)
.addComponent(jLabel4))
.addGap(18, 18, 18)
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(passfield, javax.swing.GroupLayout.DEFAULT_SIZE, 111, Short.MAX_VALUE)
.addComponent(userfield, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 111, Short.MAX_VALUE)))
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(43, 43, 43)
.addComponent(btncancel, javax.swing.GroupLayout.PREFERRED_SIZE, 102, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap())
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(46, 46, 46)
.addComponent(jLabel2))
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(64, 64, 64)
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(userfield, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel3))
.addGap(18, 18, 18)
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(passfield, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel4))))
.addGap(49, 49, 49)
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(btnlogin)
.addComponent(btncancel, javax.swing.GroupLayout.PREFERRED_SIZE, 40, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap())
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
);
pack();
}// </editor-fold>//GEN-END:initComponents
private void btnloginActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnloginActionPerformed
if(evt.getSource()==btnlogin)
{
String user = btnlogin.getText();
String pass = btncancel.getText();
if(user.equals(user)&&pass.equals(pass))
{
this.hide();
JOptionPane.showMessageDialog(null,"ACCESS GRANTED");
welcome s2 = new welcome();
s2.show();
}
else
{
JOptionPane.showMessageDialog(null,"ACCESS DENIED");
}
}
}//GEN-LAST:event_btnloginActionPerformed
private void btncancelActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btncancelActionPerformed
if(evt.getSource()==btncancel)
{
JOptionPane.showMessageDialog(null,"BYE! BYE!");
System.exit(0);
}
}//GEN-LAST:event_btncancelActionPerformed
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new keylogger().setVisible(true);
}
});
}
// Variables declaration - do not modify//GEN-BEGIN:variables
private javax.swing.JButton btncancel;
private javax.swing.JButton btnlogin;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JPasswordField passfield;
private javax.swing.JTextField userfield;
// End of variables declaration//GEN-END:variables
}