ServerSocket基础

 1.ServerSocket基础
      用于监听特定的端口，接收Socket请求
      ServerSocket server = new ServerSocket(8080);
      管理客户端连接请求是由操作系统控制的，这些连接会存入先进先出的队列中，当然队列有最大限度
      backlog参数
           ServerSocket构造方法的backlog参数用来设置连接请求队列的长度，但不能超过系统限定的长度
  一个示例：

<span>// 服务端
public static void main(String[] args) throws Exception{
    // 创建ServerSocket端口8080，请求队列最大为3
    ServerSocket server = new ServerSocket(8080,3);
    // 此时让服务端睡眠6秒，而队列中只能保存3个，所以会报错
    Thread.sleep(6000);
//        while(true){
//            Socket socket = server.accept();
//            System.out.println(socket.getInetAddress());
//        }
}</span>

<span>// 客户端
public static void main(String[] args) throws Exception{
    Socket[] sockets = new Socket[100];
    // 模拟100个连接
    for(int i=0;i<100;i++){
        sockets[i] = new Socket("192.168.1.11",8080);
        System.out.println(i+1);
    }
    Thread.sleep(3000);
    // 依次关闭
    for(int i=0;i<100;i++){
        sockets[i].close();
    }
}</span>

      服务端也可绑定固定IP
           ServerSocket server = new ServerSocket(8080,
                3,InetAddress.getByName("192.168.1.11"));

2.ServerSocket选项
      等待客户连接超时SoTimeout
            超过时间仍然没有连接，则抛SocketTimeoutException异常 
            ServerSocket server = new ServerSocket(8080);
            server.setSoTimeout(6000);
      是否允许重用服务器地址
            当ServerSocket关闭时，如果还有数据传入，并不会立即释放端口
       如果此时重启，可能会抛BindException异常
            if(!server.getResuseAddress()){
                  server.setResuseAddress(true);
            }
       需要在绑定端口前设置才能生效
       接收数据的缓冲区大小 
       示例
            ServerSocket server = new ServerSocket();
            int size = server.getReceiveBufferSize();
            server.setReceiveBufferSize(10000);// 单位为字节
            server.bind(new InetSocketAddress(8080));

3.ServerSocket的一个示例

<span>// 业务逻辑的处理放到了线程中
class Handler implements Runnable{
    
    private Socket socket;
    public Handler(Socket socket){
        this.socket = socket;
    }
    
    @Override
    public void run() {
        System.out.println("new connection:"+socket.getInetAddress());
        try {
            BufferedReader br = new BufferedReader(
                    new InputStreamReader(socket.getInputStream()));
            PrintWriter pw = new PrintWriter(
                    new OutputStreamWriter(socket.getOutputStream()));
            String msg = null;
            while((msg=br.readLine())!=null){
                System.out.println(msg);
                pw.println("received");
                if(msg.equals("88")){
                    break;
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally{
            if(socket!=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    
}
</span>

<span>        private int port = 8080;
    private ServerSocket server;
    
    public static void main(String[] args) throws Exception {
        new EchoServer().service();
    }
    
    public EchoServer()throws Exception{
        server = new ServerSocket(port);
        System.out.println("服务器启动");
    }
    
    // 进来一个用户就分配一个线程
    public void service(){
        while(true){
            Socket socket = null;
            try {
                socket = server.accept();
                Thread thread = new Thread(new Handler(socket));
                thread.start();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }</span>