Java中的actionlistener是什么？_IT百科

actionlistener字面上理解就是动作监听器。\x0d\x0a它是一个接口，在实现此接口的类中，你可以给需要关注其动作的组件（如Button）添加监听器（addActionListener(this)），之后在事件处理方法（public void actionPerformed(ActionEvent event){}）中，对每个事件进行不同处理。\x0d\x0a给你个例子吧，是我自己写的一个记事本：\x0d\x0aimport java.io.*\x0d\x0aimport java.awt.event.*\x0d\x0aimport javax.swing.*\x0d\x0apublic class MainClass extends JFrame implements ActionListener{\x0d\x0aint width = 500,height = 400\x0d\x0aJPanel panel\x0d\x0aJMenuBar bar\x0d\x0aJMenu fileMenu,editMenu,helpMenu\x0d\x0aJMenuItem 打开O,新建N,保存S,另存A,剪切T,复制C,粘贴P,关于A\x0d\x0aJTextArea textArea = null\x0d\x0aFile tempFile = null\x0d\x0apublic MainClass(){ //构造方法\x0d\x0asetTitle("TextEdit")\x0d\x0asetSize(width,height)\x0d\x0apanel = (JPanel)getContentPane()\x0d\x0abar = new JMenuBar()\x0d\x0afileMenu = new JMenu("文件F")\x0d\x0afileMenu.setMnemonic('F')\x0d\x0aeditMenu = new JMenu("编辑E")\x0d\x0aeditMenu.setMnemonic('E')\x0d\x0ahelpMenu = new JMenu("帮助H")\x0d\x0ahelpMenu.setMnemonic('H')\x0d\x0a打开O = new JMenuItem("打开O")\x0d\x0a打开O.setMnemonic('O')\x0d\x0a新建N = new JMenuItem("新建N")\x0d\x0a新建N.setMnemonic('N')\x0d\x0a保存S = new JMenuItem("保存S")\x0d\x0a保存S.setMnemonic('S')\x0d\x0a另存A = new JMenuItem("另存A")\x0d\x0a另存A.setMnemonic('A')\x0d\x0a剪切T = new JMenuItem("剪切C")\x0d\x0a剪切T.setMnemonic('t')\x0d\x0a复制C = new JMenuItem("复制C")\x0d\x0a复制C.setMnemonic('C')\x0d\x0a粘贴P = new JMenuItem("粘贴P")\x0d\x0a粘贴P.setMnemonic('P')\x0d\x0a关于A = new JMenuItem("关于A")\x0d\x0a关于A.setMnemonic('A')\x0d\x0afileMenu.add(打开O)\x0d\x0afileMenu.add(新建N)\x0d\x0afileMenu.add(保存S)\x0d\x0afileMenu.add(另存A)\x0d\x0abar.add(fileMenu)\x0d\x0aeditMenu.add(剪切T)\x0d\x0aeditMenu.add(复制C)\x0d\x0aeditMenu.add(粘贴P)\x0d\x0abar.add(editMenu)\x0d\x0ahelpMenu.add(关于A)\x0d\x0abar.add(helpMenu)\x0d\x0atextArea = new JTextArea()\x0d\x0apanel.add("North",bar)\x0d\x0apanel.add("Center", textArea)\x0d\x0a打开O.addActionListener(this)\x0d\x0a新建N.addActionListener(this)\x0d\x0a保存S.addActionListener(this)\x0d\x0a另存A.addActionListener(this)\x0d\x0a剪切T.addActionListener(this)\x0d\x0a复制C.addActionListener(this)\x0d\x0a粘贴P.addActionListener(this)\x0d\x0a关于A.addActionListener(this)\x0d\x0asetDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)\x0d\x0asetVisible(true)\x0d\x0a}\x0d\x0apublic void actionPerformed(ActionEvent event){ //处理事件\x0d\x0aif(event.getSource() == 打开O){ //处理打开\x0d\x0aJFileChooser jfc = new JFileChooser()\x0d\x0ajfc.showOpenDialog(panel)\x0d\x0atempFile = jfc.getSelectedFile()\x0d\x0aFileReader fis\x0d\x0atry {\x0d\x0afis = new FileReader(tempFile)\x0d\x0atextArea.read(fis,null)\x0d\x0atextArea.setEditable(true)\x0d\x0a}catch(Exception ex){ex.printStackTrace()}\x0d\x0a}\x0d\x0aif(event.getSource() == 新建N){ //处理新建\x0d\x0atextArea.setEditable(true)\x0d\x0atextArea.setText(null)\x0d\x0a}\x0d\x0aif(event.getSource() == 保存S){ //处理保存\x0d\x0aif(tempFile == null){\x0d\x0aJFileChooser jfc = new JFileChooser()\x0d\x0ajfc.showSaveDialog(panel)\x0d\x0atempFile = jfc.getSelectedFile()\x0d\x0atry{\x0d\x0aFileWriter fos = new FileWriter(tempFile)\x0d\x0atextArea.write(fos)\x0d\x0a}catch(Exception ex){ex.printStackTrace()}\x0d\x0a}\x0d\x0aelse{\x0d\x0atry{\x0d\x0aFileWriter fos = new FileWriter(tempFile)\x0d\x0atextArea.write(fos)\x0d\x0a}catch(Exception ex){ex.printStackTrace()}\x0d\x0a}\x0d\x0a}\x0d\x0aif(event.getSource() == 另存A){ //处理另存\x0d\x0aJFileChooser jfc = new JFileChooser()\x0d\x0ajfc.showSaveDialog(panel)\x0d\x0atempFile = jfc.getSelectedFile()\x0d\x0atry{\x0d\x0aFileWriter fos = new FileWriter(tempFile)\x0d\x0atextArea.write(fos)\x0d\x0a}catch(Exception ex){ex.printStackTrace()}\x0d\x0a}\x0d\x0aif(event.getSource() == 剪切T){ //处理剪切\x0d\x0atextArea.cut()\x0d\x0a}\x0d\x0aif(event.getSource() == 复制C){ //处理复制\x0d\x0atextArea.copy()\x0d\x0a}\x0d\x0aif(event.getSource() == 粘贴P){ //处理粘贴\x0d\x0atextArea.paste()\x0d\x0a}\x0d\x0aif(event.getSource() == 关于A){ //处理关于\x0d\x0atextArea.setText("Manifest-Version: 1.0\n" +\x0d\x0a"Created-By: Libra_JL\n" +\x0d\x0a"QQ: 254791521\n")\x0d\x0atextArea.setEditable(false)\x0d\x0apanel.validate()\x0d\x0avalidate()\x0d\x0a}\x0d\x0a}\x0d\x0apublic static void main(String []args){ //主函数\x0d\x0anew MainClass()\x0d\x0a}\x0d\x0a}

简单的例子:

import java.applet.*

import java.awt.*

import java.awt.event.*

public class TestPanel extends Applet implements ActionListener,ContainerListener

{

Panel p1,p2,p3

Label prompt1,prompt2,prompt3

Button button1

public void init()

{

setLayout(new BorderLayout())

p1=new Panel()

p1.setBackground(Color.gray)

p2=new Panel()

p2.setBackground(Color.red)

p3=new Panel()

p3.setBackground(Color.cyan)

button1=new Button("input 3panel")

button1.addActionListener(this)

prompt1=new Label("1panel")

prompt2=new Label("2panel")

prompt3=new Label("3panel")

p1.add(prompt1)

p2.add(prompt2)

p3.add(prompt3)

p3.add(button1)

p1.add(p3)

p1.addContainerListener(this)

}

public void actionPerformed(ActionEvent e)

{

if(e.getSource()==button1)

p1.remove(p3)

}

public void componentRemoved(ContainerEvent e)

{

showStatus("移除3panel")

}

public void componentAdded(ContainerEvent e)

{

}

可以捕获监听器的内容，并进行处理，参数也可以为空，空代表什么都不执行。

加了个this.addWindowListener()方法以下是代码：

import java.awt. *

import java.awt.event.*

public class AddDemo extends Frame implements ActionListener//实现相应接口

{

Label l1,l2

TextField t1,t2,t3

Button b

public AddDemo()

{

l1=new Label("加数1：",Label.CENTER)

l2=new Label("加数2：",Label.CENTER)

t1=new TextField(6)

t2=new TextField(6)

t3=new TextField(6)

t3.setEditable(false)

b=new Button("求和")

setLayout(new GridLayout(3,2))

add(l1)

add(t1)

add(l2)

add(t2)

add(b)

add(t3)

b.addActionListener(this)

setSize(200,160)

setVisible(true)

setLocation(400,200)

this.addWindowListener(new WindowListener(){

@Override

public void windowActivated(WindowEvent arg0) {