Java Smack如何处理连接断开

Smack 是一个用于处理 XMPP（可扩展消息与出席协议）的 Java 库。处理连接断开的方法如下：

1. 添加依赖

首先，确保在项目的 pom.xml 文件中添加了 Smack 库的依赖：

<dependency>     <groupId>org.igniterealtime.smack</groupId>     <artifactId>smack-java7</artifactId>     <version>4.4.2</version> </dependency> <dependency>     <groupId>org.igniterealtime.smack</groupId>     <artifactId>smack-tcp</artifactId>     <version>4.4.2</version> </dependency> <dependency>     <groupId>org.igniterealtime.smack</groupId>     <artifactId>smack-extensions</artifactId>     <version>4.4.2</version> </dependency> 

2. 建立连接

使用 Smack 库建立 XMPP 连接：

import org.jivesoftware.smack.Connection; import org.jivesoftware.smack.ConnectionConfiguration; import org.jivesoftware.smack.XMPPException; import org.jivesoftware.smack.tcp.XMPPTCPConnection; import org.jivesoftware.smack.tcp.XMPPTCPConnectionConfiguration;  public class SmackDemo {     public static void main(String[] args) {         ConnectionConfiguration config = new XMPPTCPConnectionConfiguration.Builder("example.com")                 .setUsernameAndPassword("username", "password")                 .setSecurityMode(ConnectionConfiguration.SecurityMode.disabled)                 .build();          Connection connection = new XMPPTCPConnection(config);         try {             connection.connect();         } catch (XMPPException e) {             e.printStackTrace();         }     } } 

3. 处理连接断开

为了处理连接断开，需要实现 Connection.Listener 接口并重写 connectionClosed() 方法。例如：

import org.jivesoftware.smack.Connection; import org.jivesoftware.smack.ConnectionConfiguration; import org.jivesoftware.smack.XMPPException; import org.jivesoftware.smack.tcp.XMPPTCPConnection; import org.jivesoftware.smack.tcp.XMPPTCPConnectionConfiguration;  public class SmackDemo {     public static void main(String[] args) {         ConnectionConfiguration config = new XMPPTCPConnectionConfiguration.Builder("example.com")                 .setUsernameAndPassword("username", "password")                 .setSecurityMode(ConnectionConfiguration.SecurityMode.disabled)                 .build();          Connection connection = new XMPPTCPConnection(config);         connection.addAsyncStanzaListener(new StanzaTypeFilter(Message.class), new MessageListener());         connection.addAsyncStanzaListener(new StanzaTypeFilter(Presence.class), new PresenceListener());         try {             connection.connect();         } catch (XMPPException e) {             e.printStackTrace();         }     }      static class MessageListener implements StanzaListener {         @Override         public void processStanza(Stanza stanza) {             // 处理消息         }     }      static class PresenceListener implements StanzaListener {         @Override         public void processStanza(Stanza stanza) {             // 处理在线状态         }     }      public static class MyConnectionListener implements Connection.Listener {         @Override         public void connectionClosed() {             System.out.println("连接已断开");             // 在这里处理连接断开后的逻辑，例如重新连接或清理资源         }          @Override         public void connectionFailed(Exception e) {             System.out.println("连接失败");             e.printStackTrace();         }     } } 

在这个例子中，我们创建了一个名为 MyConnectionListener 的类，实现了 Connection.Listener 接口。我们重写了 connectionClosed() 方法，当连接断开时，这个方法会被调用。在这个方法里，你可以处理连接断开后的逻辑，例如重新连接或清理资源。