tcp nio 服务端、客户端例子--参考《分布式Java应用：基础与实践》

最新推荐文章于 2025-01-10 00:48:56 发布

yangwm

最新推荐文章于 2025-01-10 00:48:56 发布

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分类专栏： java 文章标签： java tcp exception string command server

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本文介绍了一个基于TCP/IP+NIO实现的服务端与客户端通信的Java代码示例。该示例支持可变长消息读取，并针对readException、oppositecloseException及selecttimeoutException等异常进行了特殊处理。

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参考《分布式java应用》tcp nio 服务端、客户端例子，在基础主要做了以下调整：

1. 信息长度由定长（ByteBuffer长度）修正为可变长（即不再收长度限制）

2. 特殊错误处理：read Exception，opposite close Exception，select timeout Exception（网络超时）。

read Exception 与 opposite close Exception 的处理，用于解决发现异常后造成程序的 while死循环。

select timeout Exception的处理，用于对网络超时的支持。

/**
*
*/

package distributed.tcpnio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;

/**
* 实现TCP/IP+NIO 方式的系统间通讯的代码，服务器端：
* SocketChannel和ServerSocketChannel两个关键的类，网络IO 的操作则改为通过ByteBuffer来实现。
*
* @author yangwm in Mar 22, 2010 5:52:58 PM
*/
public class ServerTcpNio {

    /**
     * create by yangwm in Mar 22, 2010 5:52:58 PM
     * @param args
     * @throws IOException
     */
    public static void main(String[] args) throws IOException {
        int port = 9527;
        System.out.println("Server listen on port: " + port);

        Selector selector = Selector.open();

        ServerSocketChannel serverChannel = ServerSocketChannel.open();
        ServerSocket serverSocket = serverChannel.socket();
        serverSocket.bind(new InetSocketAddress(port));
        serverChannel.configureBlocking(false);

        serverChannel.register(selector, SelectionKey.OP_ACCEPT);
        while (true) {
            int nKeys = selector.select();
            if (nKeys > 0) {
                for (SelectionKey selectionKey : selector.selectedKeys()) {
                    if (selectionKey.isAcceptable()) {
                        ServerSocketChannel tempServerChannel = (ServerSocketChannel)selectionKey.channel();
                        SocketChannel socketChannel = tempServerChannel.accept();
                        if (socketChannel == null) {
                            continue;
                        }

                        socketChannel.configureBlocking(false);
                        socketChannel.register(selector, SelectionKey.OP_READ);
                    } else if (selectionKey.isReadable()) {
                        //try { Thread.sleep(5000); } catch (InterruptedException e) { e.printStackTrace(); }
                        SocketChannel socketChannel = (SocketChannel)selectionKey.channel();

                        StringBuilder sb = new StringBuilder();
                        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                        try {
                            int readBytes = 0;
                            int ret = 0;
                            while ((ret = socketChannel.read(byteBuffer)) > 0) {
                                readBytes += ret;
                                byteBuffer.flip();

                                sb.append(Charset.forName("UTF-8").decode(byteBuffer).toString());

                                byteBuffer.clear();
                            }

                            if (readBytes == 0) {
                                /*
                                 * handle Exception
                                 */
                                System.err.println("handle opposite close Exception");
                                socketChannel.close();
                            }


                            String message = sb.toString();
                            System.out.println("Message from client: " + message);
                            if ("quit".equalsIgnoreCase(message.toString().trim())) {
                                System.out.println("Client has been quit!");

                                socketChannel.close();
                            } else if ("serverquit".equalsIgnoreCase(message.trim())) {
                                System.out.println("Server has been shutdown!");

                                socketChannel.close();
                                serverChannel.close();
                                selector.close();
                                System.exit(0);
                            } else {
                                String outMessage = "Server response：" + message;
                                socketChannel.write(Charset.forName("UTF-8").encode(outMessage));
                            }
                        } catch (IOException e) {
                            /*
                             * handle Exception
                             */
                            System.err.println("handle read Exception");
                            socketChannel.close();
                        } finally {
                            byteBuffer.clear();
                        }

                    }
                }
                selector.selectedKeys().clear();

            }
        }
    }

}

/**
*
*/
package distributed.tcpnio;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;

/**
* 实现TCP/IP+NIO 方式的系统间通讯的代码，客户端：
*
* @author yangwm in Mar 22, 2010 10:19:51 PM
*/
public class ClientTcpNio {

    /**
     * create by yangwm in Mar 22, 2010 10:19:52 PM
     * @param args
     * @throws IOException
     */
    public static void main(String[] args) throws IOException {
        String host = "127.0.0.1";
        int port = 9527;

        Selector selector = Selector.open();

        SocketChannel clientChannel = SocketChannel.open();
        clientChannel.configureBlocking(false);
        clientChannel.connect(new InetSocketAddress(host, port));

        clientChannel.register(selector, SelectionKey.OP_CONNECT);

        BufferedReader systemIn = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            if (clientChannel.isConnected()) {
                String command = systemIn.readLine();
                clientChannel.write(Charset.forName("UTF-8").encode(command));

                if (command == null || "quit".equalsIgnoreCase(command)) {
                    System.out.println("Client quit!");

                    systemIn.close();
                    clientChannel.close();
                    selector.close();
                    System.exit(0);
                }

            }

            int nKeys = selector.select(3 * 1000);
            if (nKeys > 0) {
                for (SelectionKey selectionKey : selector.selectedKeys()) {
                    if (selectionKey.isConnectable()) {
                        SocketChannel socketChannel = (SocketChannel)selectionKey.channel();
                        socketChannel.configureBlocking(false);
                        socketChannel.register(selector, SelectionKey.OP_READ);
                        socketChannel.finishConnect();
                    } else if (selectionKey.isReadable()) {
                        SocketChannel socketChannel = (SocketChannel)selectionKey.channel();
                        StringBuilder sb = new StringBuilder();

                        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                        try {
                            int readBytes = 0;
                            int ret = 0;
                            while ((ret = socketChannel.read(byteBuffer)) > 0) {
                                readBytes += ret;
                                byteBuffer.flip();

                                sb.append(Charset.forName("UTF-8").decode(byteBuffer).toString());

                                byteBuffer.clear();
                            }

                            if (readBytes == 0) {
                                /*
                                 * handle Exception
                                 */
                                System.err.println("handle opposite close Exception");
                                socketChannel.close();
                            }
                        } catch (IOException e) {
                            /*
                             * handle Exception
                             */
                            System.err.println("handle read Exception");
                            socketChannel.close();
                        } finally {
                            byteBuffer.clear();
                        }

                        String message = sb.toString();
                        System.out.println(message);
                    }
                }
                selector.selectedKeys().clear();

            } else {
                /*
                 * handle Exception
                 */
                System.err.println("handle select timeout Exception");
                clientChannel.close();
            }

        }
    }

}