nio簡單demo，幫助理解io與nio區別

服務器

        import java.io.IOException;
        import java.net.InetSocketAddress;
        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;
        import java.util.Iterator;

public class NIOServer1 {
    // 本地字符集
    private static final String LocalCharSetName = "UTF-8";

    // 本地服務器監聽的端口
    private static final int Listenning_Port = 8888;

    // 緩衝區大小
    private static final int Buffer_Size = 1024;

    // 超時時間,單位毫秒
    private static final int TimeOut = 3000;

    public static void main(String[] args) throws IOException {
        // 創建一個在本地端口進行監聽的服務Socket信道.並設置爲非阻塞方式
        ServerSocketChannel serverChannel = ServerSocketChannel.open();

        serverChannel.socket().bind(new InetSocketAddress(Listenning_Port));
        serverChannel.configureBlocking(false);

        // 創建一個選擇器並將serverChannel註冊到它上面
        Selector selector = Selector.open();
        serverChannel.register(selector, SelectionKey.OP_ACCEPT);

        while (true) {
            // 等待某個信道就緒
            if (selector.select(TimeOut) == 0) {
                System.out.println(".");
                continue;
            }

            // 獲得就緒信道的鍵迭代器
            Iterator<SelectionKey> keyIter = selector.selectedKeys().iterator();

            // 使用迭代器進行遍歷就緒信道
            while (keyIter.hasNext()) {
                SelectionKey key = keyIter.next();
                // 這種情況是有客戶端連接過來,準備一個clientChannel與之通信
                if (key.isAcceptable()) {
                    SocketChannel clientChannel = ((ServerSocketChannel) key.channel()).accept();
                    clientChannel.configureBlocking(false);
                    clientChannel.register(selector, SelectionKey.OP_READ,
                            ByteBuffer.allocate(Buffer_Size));
                }

                // 客戶端有寫入時
                if (key.isReadable()) {
                    // 獲得與客戶端通信的信道
                    SocketChannel clientChannel = (SocketChannel) key.channel();

                    // 得到並重置緩衝區的主要索引值
                    ByteBuffer buffer = (ByteBuffer) key.attachment();
                    buffer.clear();

                    // 讀取信息獲得讀取的字節數
                    long bytesRead = clientChannel.read(buffer);

                    if (bytesRead == -1) {
                        // 沒有讀取到內容的情況
                        clientChannel.close();
                    } else {
                        // 將緩衝區準備爲數據傳出狀態
                        buffer.flip();
                        // 將獲得字節字符串(使用Charset進行解碼)
                        String receivedString = Charset
                                .forName(LocalCharSetName).newDecoder().decode(buffer).toString();

                        // 控制檯打印出來
                        System.out.println("接收到信息:" + receivedString);

                        // 準備發送的文本
                        String sendString = "你好,客戶端. 已經收到你的信息" + receivedString;

                        // 將要發送的字符串編碼(使用Charset進行編碼)後再進行包裝
                        buffer = ByteBuffer.wrap(sendString.getBytes(LocalCharSetName));

                        // 發送回去
                        clientChannel.write(buffer);

                        // 設置爲下一次讀取或是寫入做準備
                        key.interestOps(SelectionKey.OP_READ | SelectionKey.OP_WRITE);
                    }
                }

                keyIter.remove();
            }
        }

    }
}

客戶端

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;

public class NIOClient1Test {

    public static void main(String[] args) throws UnknownHostException,
            IOException {
        Socket s = new Socket("localhost", 8888);

        InputStream inStream = s.getInputStream();
        OutputStream outStream = s.getOutputStream();

        // 輸出
        PrintWriter out = new PrintWriter(outStream, true);
        out.println("getPublicKey你好！");
        out.flush();

        s.shutdownOutput();// 輸出結束

        // 輸入
        Scanner in = new Scanner(inStream);

        StringBuilder sb = new StringBuilder();
        while (in.hasNextLine()) {
            String line = in.nextLine();
            sb.append(line);
        }

        String response = sb.toString();
        System.out.println("response=" + response);

    }
}