我想阻止在java中启动多个应用程序实例。我知道两种方法：
但哪一种更有效，更好用？我应该使用哪一个？
也欢迎任何其他解决方案。
答案 0 :(得分：3)
有一个名为jUnique的库，可以帮助您自己实现它。
答案 1 :(得分：2)
如果使用Java WebStart进行部署，则SingleInstanceService会执行此操作。
请参阅http://download.oracle.com/javase/6/docs/technotes/guides/javaws/developersguide/faq.html#218
答案 2 :(得分：1)
我的投票是锁定端口（我认为这是你的意思是套接字）。我不知道确切的原因。但事实上，在大多数实际项目中，我只是将其作为解决方案。虽然我很乐意听到其他方式。
答案 3 :(得分：1)
在回答您的问题时，端口解决方案将从机器中获取更多资源：
- 您将保持端口锁定：端口有限，您可能会发现防火墙或其他程序在同一端口上侦听时出现问题。
- 您需要一个活动线程。
文件解决方案将使用来自机器的更少资源，以避免在运行时的addShutdownHook方法中永久锁定文件，以便删除文件。
答案 4 :(得分：1)
public interface ApplicationStartedListener {
void applicationStarted();
void foreignApplicationStarted(String name);
void messageArrived(Object obj);
}
//
import java.io.Serializable;
public class ClassCheck implements Serializable {
private static final long serialVersionUID = 1L;
private String className = null;
public ClassCheck() {
}
public ClassCheck(String className) {
setClassName(className);
}
@Override
public String toString() {
return this.className;
}
public String getClassName() {
return this.className;
}
public void setClassName(String className) {
this.className = className;
}
}
//
import java.awt.AWTException;
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.MouseInfo;
import java.awt.Point;
import java.awt.Robot;
import java.awt.event.InputEvent;
import java.io.File;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class RunOnceFromFile {
private SingleInstanceController sic = null;
private JFrame frame;
private Robot r;
private JTextField tf;
public RunOnceFromFile() {
try {
r = new Robot();
} catch (AWTException ex) {
ex.printStackTrace();
}
sic = new SingleInstanceController(new File(System.getProperty("java.io.tmpdir") + "Example.file"), "sic_example_application");
if (sic.isOtherInstanceRunning()) {
sic.sendMessageToRunningApplication("toFront");
System.exit(0);
} else {
frame = new JFrame("TEST");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 300);
tf = new JTextField("JTextFiled");
frame.add(tf, BorderLayout.NORTH);
frame.setExtendedState(Frame.ICONIFIED);
frame.setExtendedState(Frame.NORMAL);
frame.setExtendedState(frame.getExtendedState() | JFrame.ICONIFIED);
frame.setExtendedState(frame.getExtendedState() & (~JFrame.ICONIFIED));
frame.setLocationRelativeTo(null);
frame.setVisible(true);
sic.registerApplication();
sic.addApplicationStartedListener(new ApplicationStartedListener() {
public void applicationStarted() {
Runnable doRun = new Runnable() {
public void run() {
frame.toFront();
}
};
SwingUtilities.invokeLater(doRun);
}
public void foreignApplicationStarted(final String name) {
Runnable doRun = new Runnable() {
public void run() {
frame.toFront();
}
};
SwingUtilities.invokeLater(doRun);
}
public void messageArrived(final Object obj) {
Runnable doRun = new Runnable() {//activateWindow(frame);
public void run() {
frame.toFront();
}
};
SwingUtilities.invokeLater(doRun);
}
private void activateWindow(JFrame frame) {
frame.setExtendedState(Frame.ICONIFIED);
frame.setExtendedState(Frame.NORMAL);
frame.setAlwaysOnTop(true);
frame.setAlwaysOnTop(false);
Point location = MouseInfo.getPointerInfo().getLocation();
Point locationOnScreen = frame.getLocationOnScreen();
r.mouseMove(locationOnScreen.x + 100, locationOnScreen.y + 10);
r.mousePress(InputEvent.BUTTON1_MASK);
r.mouseRelease(InputEvent.BUTTON1_MASK);
r.mouseMove(location.x, location.y);
}
});
}
}
public static void main(String[] args) {
RunOnceFromFile roff = new RunOnceFromFile();
}
}
//
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
public class SingleInstanceController {
private String appname = null;
private Socket client = null;
private File file = null;
private ArrayList<ApplicationStartedListener> listener = null;
private ObjectInputStream ois = null;
private ObjectOutputStream oos = null;
private boolean result = false;
private ServerSocket server = null;
public SingleInstanceController(String appname) {
this(new File(System.getProperty("java.io.tmpdir") + "/923jhakE53Kk9235b43.6m7"), appname);
}
public SingleInstanceController(File file, String appname) {
this.file = file;
this.appname = appname;
this.listener = new ArrayList<ApplicationStartedListener>();
}
public void addApplicationStartedListener(ApplicationStartedListener asl) {
this.listener.add(asl);
}
public void removeApplicationStartedListener(ApplicationStartedListener asl) {
this.listener.remove(asl);
}
public boolean isOtherInstanceRunning() {
if (!this.file.exists()) {
return false;
}
return sendMessageToRunningApplication(new ClassCheck(this.appname));
}
public boolean sendMessageToRunningApplication(final Object obj) {
this.result = false;
try {
this.client = new Socket("localhost", getPortNumber());
new Thread(new Runnable() {
public void run() {
try {
SingleInstanceController.this.oos = new ObjectOutputStream(SingleInstanceController.this.client.getOutputStream());
SingleInstanceController.this.ois = new ObjectInputStream(SingleInstanceController.this.client.getInputStream());
SingleInstanceController.this.oos.writeObject(obj);
SingleInstanceController.this.oos.flush();
SingleInstanceController.this.result = SingleInstanceController.this.ois.readBoolean();
} catch (IOException e) {
SingleInstanceController.this.result = false;
}
}
}).start();
for (int i = 0; i < 10; i++) {
if (this.result == true) {
break;
}
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
this.client.close();
return this.result;
} catch (IOException e) {
return false;
}
}
public boolean registerApplication() {
try {
if (!this.file.exists()) {
if (!this.file.getParentFile().mkdirs() && !this.file.getParentFile().exists()) {
return false;
}
if (!this.file.createNewFile()) {
return false;
}
}
BufferedWriter wuffy = new BufferedWriter(new FileWriter(this.file));
int port = getFreeServerSocket();
if (port != -1) {
startServer();
}
wuffy.write(String.valueOf(port));
wuffy.close();
return true;
} catch (IOException e) {
return false;
}
}
protected void messageArrived(Object obj) {
for (ApplicationStartedListener asl : this.listener) {
asl.messageArrived(obj);
}
}
protected void applicationStartet() {
for (ApplicationStartedListener asl : this.listener) {
asl.applicationStarted();
}
}
protected void foreignApplicationStarted(String name) {
for (ApplicationStartedListener asl : this.listener) {
asl.foreignApplicationStarted(name);
}
}
private int getPortNumber() {
try {
BufferedReader buffy = new BufferedReader(new FileReader(this.file));
int port = Integer.parseInt(buffy.readLine().trim());
buffy.close();
return port;
} catch (Exception e) {
return -1;
}
}
private void startServer() {
new Thread(new Runnable() {
public void run() {
while (true) {
try {
SingleInstanceController.this.client = SingleInstanceController.this.server.accept();
if (SingleInstanceController.this.client.getInetAddress().isLoopbackAddress()) {
new Thread(new Runnable() {
public void run() {
try {
SingleInstanceController.this.oos = new ObjectOutputStream(SingleInstanceController.this.client.getOutputStream());
SingleInstanceController.this.ois = new ObjectInputStream(SingleInstanceController.this.client.getInputStream());
Object obj = SingleInstanceController.this.ois.readObject();
if (obj instanceof ClassCheck) {
if (obj.toString().equals(SingleInstanceController.this.appname)) {
SingleInstanceController.this.oos.writeBoolean(true);
applicationStartet();
} else {
SingleInstanceController.this.oos.writeBoolean(false);
foreignApplicationStarted(obj.toString());
}
} else {
messageArrived(obj);
SingleInstanceController.this.oos.writeBoolean(true);
}
SingleInstanceController.this.oos.flush();
SingleInstanceController.this.client.close();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}).start();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}).start();
}
private int getFreeServerSocket() {
for (int i = 2000; i < 10000; i++) {
try {
this.server = new ServerSocket(i);
return i;
} catch (IOException ignore) {
}
}
return -1;
}
}
答案 5 :(得分：0)
serversocket解决方案是跨平台的。并且不会受到程序崩溃和重置锁定的影响。
答案 6 :(得分：0)
文件锁定是更好的方法。在用户的主目录中创建文件时，这仍然可以在多用户环境中使用。
我遇到了 - JUnique--没有机会使用它 http://www.sauronsoftware.it/projects/junique/manual.php
答案 7 :(得分：0)
我知道这个问题很老了，但我现在必须解决同样的问题。我更喜欢套接字解决方案，因为我从未想过这样的任务应该与文件系统有任何关系。最好解决内存中的问题，而不是我认为的文件系统。