Question

apache mina 是长连接还是短连接

Answer 1

长短都有。给你示例：
1长连接客户端
使用java.net.Socket来实现向服务端建立连接。Socket建立后一直保持连接，从服务端接收到数据包后直接将原文返回。
public class TcpKeepAliveClient {
private String ip;
private int port;
private static Socket socket = null;
private static int timeout = 50 * 1000;

public TcpKeepAliveClient(String ip, int port) {
this.ip = ip;
this.port = port;
}

public void receiveAndSend() throws IOException {
InputStream input = null;
OutputStream output = null;

try {
if (socket == null ||socket.isClosed() || !socket.isConnected()) {
socket = new Socket();
InetSocketAddress addr = new InetSocketAddress(ip, port);
socket.connect(addr, timeout);
socket.setSoTimeout(timeout);
System.out.println("TcpKeepAliveClientnew ");
}

input = socket.getInputStream();
output = socket.getOutputStream();

// read body
byte[] receiveBytes = {};// 收到的包字节数组
while (true) {
if (input.available() > 0) {
receiveBytes = new byte[input.available()];
input.read(receiveBytes);

// send
System.out.println("TcpKeepAliveClientsend date :" +new String(receiveBytes));
output.write(receiveBytes, 0, receiveBytes.length);
output.flush();
}
}

} catch (Exception e) {
e.printStackTrace();
System.out.println("TcpClientnew socket error");
}
}

public static void main(String[] args) throws Exception {
TcpKeepAliveClient client = new TcpKeepAliveClient("127.0.0.1", 8002);
client.receiveAndSend();
}

}
2短连接客户端
服务启动
public class MinaShortClient {
private static final int PORT = 8001;

public static void main(String[] args) throws IOException,InterruptedException {
IoConnector connector = new NioSocketConnector();
connector.getSessionConfig().setReadBufferSize(2048);

connector.getFilterChain().addLast("logger", new LoggingFilter());
connector.getFilterChain().addLast("codec", newProtocolCodecFilter(newTextLineCodecFactory(Charset.forName("UTF-8"))));

connector.setHandler(new MinaShortClientHandler());
for (int i = 1; i <= 10; i++) {
ConnectFuture future = connector.connect(new InetSocketAddress("127.0.0.1",PORT));
future.awaitUninterruptibly();
IoSession session =future.getSession();
session.write(i);
session.getCloseFuture().awaitUninterruptibly();

System.out.println("result=" + session.getAttribute("result"));
}
connector.dispose();

}
}
消息处理
public class MinaShortClientHandler extends IoHandlerAdapter{
private final Logger logger = (Logger) LoggerFactory.getLogger(getClass());

public MinaShortClientHandler() {

}

@Override
public void sessionOpened(IoSession session) {
}

@Override
public void messageReceived(IoSession session, Object message) {
logger.info("Messagereceived in the client..");
logger.info("Message is:" + message.toString());
session.setAttribute("result", message.toString());
session.close(true);
}

@Override
public void exceptionCaught(IoSession session, Throwable cause) {
session.close(true);
}
}

通过本文中的例子，Apache Mina在服务端可实现TCP协议长连接和短连接。在客户端只实现了短连接模式，长连接模式也是可以实现的（在本文中还是采用传统的java Socket方式）。两个服务端之间通过共享内存的方式来传递连接对象也许有更好的实现方式。