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。