Java 如何使JButton每次单击时显示2种不同的模式?
我正在尝试实现一个JButton,它根据是否连接到服务器来显示Connect或Disconnect。因此,当我点击按钮,当它说连接时,它将连接到服务器,然后它将显示断开连接。当我单击Disconnect时,它将与服务器断开连接,按钮将再次显示connect。但是,当我单击按钮时,什么也没有发生Java 如何使JButton每次单击时显示2种不同的模式?,java,swing,jbutton,action,Java,Swing,Jbutton,Action,我正在尝试实现一个JButton,它根据是否连接到服务器来显示Connect或Disconnect。因此,当我点击按钮,当它说连接时,它将连接到服务器,然后它将显示断开连接。当我单击Disconnect时,它将与服务器断开连接,按钮将再次显示connect。但是,当我单击按钮时,什么也没有发生 btnConnect.addMouseListener(new MouseAdapter() { @Override public void
btnConnect.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent arg0) {
if (btnConnect.getText().equals("Connect")){
btnConnect.setText("Disconnect");
try {
int portNum = 5520;
String hostAddress = Actual_IP_Address.getText();
sock = new Socket(hostAddress, portNum);
writeSock = new PrintWriter ( sock.getOutputStream(), true);
readSock = new BufferedReader (new InputStreamReader(sock.getInputStream()));
}
catch(Exception ex) {
System.out.println("Error: " + ex);
sock = null;
}
}
if (btnConnect.getText().equals("Disconnect")){
btnConnect.setText("Connect");
try {
readSock.close();
writeSock.close();
sock.close();
sock = null;
}
catch(Exception ex) {
System.out.println("Error: " + ex);
sock = null;
}
}
}}
);
为什么当我单击按钮时,它只显示Connect?现在,代码的基本轮廓是
if (button.getText().equals("Connect"){
button.setText("Disconnect")
}
if (button.getText().equals("Disconnect"){
button.setText("Connect")
}
看起来正在发生的事情是,您正在将按钮文本值更改为“断开连接”,就像您应该做的那样。但紧接着,再次检查按钮文本值是否等于“Disconnect”,并再次更改。将两个if语句改为else-if语句
if (button.getText().equals("Connect"){
button.setText("Disconnect")
} else if (button.getText().equals("Disconnect"){
button.setText("Connect")
}
这个“基本”问题是,当连接时,您将按钮文本设置为Disconnect
,然后立即检查文本是否为Disconnect
,并将其设置回Connect
更大的问题是您正在耦合您的代码,这将使您很难管理UI并使其与实际发生的事情保持同步-如果套接字意外断开连接会发生什么情况
另一个问题是,您可能会阻塞UI,这会导致它“冻结”并变得无响应,因为套接字可能需要几秒钟才能建立
更好的解决方案是尝试将UI与套接字解耦,并依赖某种观察者模式,以便在套接字状态更改时通知您,而不管UI是停止套接字还是由于其他条件而停止
就我个人而言,我会使用一个SwingWorker
,因为它允许您将长时间运行/阻塞操作重载到另一个线程,但提供了许多有用的机制来安全地将更新传递回UI线程(即事件调度线程),例如
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JButton doStuff;
private SocketWorker worker;
public TestPane() {
setLayout(new GridBagLayout());
doStuff = new JButton("Connect");
doStuff.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent event) {
if (worker == null) {
doStuff.setText("...");
worker = new SocketWorker("hostname");
worker.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if ("state".equals(evt.getPropertyName())) {
System.out.println(worker.getState());
switch (worker.getState()) {
case STARTED:
doStuff.setText("Disconnect");
break;
case DONE:
worker = null;
doStuff.setText("Connect");
break;
}
}
}
});
worker.execute();
} else {
System.out.println("...");
try {
worker.stop();
} catch (IOException ex) {
ex.printStackTrace();
}
doStuff.setText("Connect");
}
}
});
add(doStuff);
}
}
public class SocketWorker extends SwingWorker<Void, Void> {
private Socket socket;
private String hostName;
private PrintWriter writeSock;
private BufferedReader readSock;
public SocketWorker(String hostName) {
this.hostName = hostName;
}
@Override
protected Void doInBackground() throws Exception {
// This is just here to demonstrate the point
Thread.sleep(5000);
//int portNum = 5520;
//socket = new Socket(hostName, portNum);
//writeSock = new PrintWriter(socket.getOutputStream(), true);
//readSock = new BufferedReader(new InputStreamReader(socket.getInputStream()));
// Do your socket handling here...
return null;
}
public void stop() throws IOException {
if (socket == null) { return; }
socket.close();
}
}
}
导入java.awt.GridBagLayout;
导入java.awt.event.ActionEvent;
导入java.awt.event.ActionListener;
导入java.beans.PropertyChangeEvent;
导入java.beans.PropertyChangeListener;
导入java.io.BufferedReader;
导入java.io.IOException;
导入java.io.PrintWriter;
导入java.net.Socket;
导入javax.swing.JButton;
导入javax.swing.JFrame;
导入javax.swing.JPanel;
导入javax.swing.SwingUtilities;
导入javax.swing.SwingWorker;
公开课考试{
公共静态void main(字符串[]args){
新测试();
}
公开考试(){
SwingUtilities.invokeLater(新的Runnable(){
@凌驾
公开募捐{
JFrame=新JFrame();
frame.add(newtestpane());
frame.pack();
frame.setLocationRelativeTo(空);
frame.setVisible(true);
}
});
}
公共类TestPane扩展了JPanel{
私人杜斯塔夫;
私人网络工人;
公共测试窗格(){
setLayout(新的GridBagLayout());
doStuff=新的JButton(“连接”);
addActionListener(新的ActionListener(){
@凌驾
已执行的公共无效操作(操作事件){
if(worker==null){
doStuff.setText(“…”);
worker=新的SocketWorker(“主机名”);
worker.addPropertyChangeListener(新的PropertyChangeListener(){
@凌驾
公共作废属性更改(属性更改事件evt){
if(“state”.equals(evt.getPropertyName())){
System.out.println(worker.getState());
开关(worker.getState()){
案件开始:
doStuff.setText(“断开”);
打破
案件完成:
worker=null;
doStuff.setText(“连接”);
打破
}
}
}
});
worker.execute();
}否则{
System.out.println(“…”);
试一试{
工人。停止();
}捕获(IOEX异常){
例如printStackTrace();
}
doStuff.setText(“连接”);
}
}
});
添加(doStuff);
}
}
公共类SocketWorker扩展SwingWorker{
专用插座;
私有字符串主机名;
私人印刷撰稿人writeSock;
专用缓冲读卡器读卡器;
公共SocketWorker(字符串主机名){
this.hostName=主机名;
}
@凌驾
受保护的Void doInBackground()引发异常{
//这只是为了证明这一点
睡眠(5000);
//int-portNum=5520;
//套接字=新套接字(主机名、端口号);
//writeSock=新的PrintWriter(socket.getOutputStream(),true);
//readSock=new BufferedReader(新的InputStreamReader(socket.getInputStream());
//在这里做你的插座处理。。。
返回null;
}
public void stop()引发IOException{
如果(socket==null){return;}
socket.close();
}
}
}
在本例中,我刚刚使用了Thread.sleep
来放置一个“mock”操作。我会考虑做你所有的事情