java-socket编程

先前有篇博文专门写了socket的基本概念，这里用java来实现简单的server-client的socket数据传输。

server端

/** * socket服务端 *  * @author peter_wang * @create-time 2014-8-30 下午3:25:27 */public class Server {    public static void main(String args[])        throws IOException {        int port = 8888;        ServerSocket server = new ServerSocket(port);        while (true) {            // 开始接受socket请求            Socket socket = server.accept();            // 建立新线程处理新进的socket请求            new Thread(new Task(socket)).start();        }    }    /**     * 处理Socket请求的异步任务     */    static class Task        implements Runnable {        private Socket mSocket;        public Task(Socket socket) {            this.mSocket = socket;        }        public void run() {            try {                handleSocket();            }            catch (Exception e) {                e.printStackTrace();            }        }        /**         * 跟客户端Socket进行通信         *          * @throws Exception         */        private void handleSocket()            throws Exception {            BufferedReader br = new BufferedReader(new InputStreamReader(mSocket.getInputStream(), "UTF-8"));            StringBuilder sb = new StringBuilder();            String temp;            int index;            while ((temp = br.readLine()) != null) {                // 遇到eof时结束接收                if ((index = temp.indexOf("eof")) != -1) {                    System.out.println(temp);                    sb.append(temp.substring(0, index));                    break;                }                sb.append(temp);            }            System.out.println("data from client: " + sb);            // 写操作            Writer writer = new OutputStreamWriter(mSocket.getOutputStream());            writer.write("Hello Client.");            writer.write("eof\n");            writer.flush();            writer.close();            br.close();            mSocket.close();        }    }}

client端

/** * socket客户端 *  * @author peter_wang * @create-time 2014-8-30 下午4:13:11 */public class Client {    public static void main(String args[])        throws Exception {        String host = "127.0.0.1"; // 本地地址        int port = 8888;        // 与服务端建立连接        Socket client = new Socket(host, port);        Scanner sc = new Scanner(System.in);        String str = sc.nextLine();        System.out.println("输入的内容为：" + str);        // 建立连接后就可以往服务端写数据了        Writer writer = new OutputStreamWriter(client.getOutputStream(), "UTF-8");        writer.write(str);        writer.write("eof\n");        writer.flush();        // 写完以后进行读操作        BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));        StringBuffer sb = new StringBuffer();        String temp;        int index;        while ((temp = br.readLine()) != null) {            if ((index = temp.indexOf("eof")) != -1) {                sb.append(temp.substring(0, index));                break;            }            sb.append(temp);        }        System.out.println("from server: " + sb);        writer.close();        br.close();        client.close();    }}

1.用了eof做完读写结束标识。

2.BufferedReader提高了IO效率，用异步提前准备好数据存储到内存，读取直接从内存读，如果数据来源于磁盘IO或网络IO，速度将快很多，磁盘读取和内存读取的速度对比参见这篇文章。

3.server和client之间数据传输需要统一编码，防止乱码。

4.源码分析，server端的new ServerSocket(port)实现了new socket、bind、listener功能

public void bind(SocketAddress endpoint, int backlog) throws IOException {if (isClosed())    throw new SocketException("Socket is closed");if (!oldImpl && isBound())    throw new SocketException("Already bound");if (endpoint == null)    endpoint = new InetSocketAddress(0);if (!(endpoint instanceof InetSocketAddress))    throw new IllegalArgumentException("Unsupported address type");InetSocketAddress epoint = (InetSocketAddress) endpoint;if (epoint.isUnresolved())    throw new SocketException("Unresolved address");if (backlog < 1)  backlog = 50;try {    SecurityManager security = System.getSecurityManager();    if (security != null)security.checkListen(epoint.getPort());    getImpl().bind(epoint.getAddress(), epoint.getPort());    getImpl().listen(backlog);    bound = true;} catch(SecurityException e) {    bound = false;    throw e;} catch(IOException e) {    bound = false;    throw e;}    }

client端的new Socket(host, port)实现了new socket和connect功能

private Socket(SocketAddress address, SocketAddress localAddr,   boolean stream) throws IOException {setImpl();// backward compatibilityif (address == null)    throw new NullPointerException();try {    createImpl(stream);    if (localAddr != null)bind(localAddr);    if (address != null)connect(address);} catch (IOException e) {    close();    throw e;}    }