nio简单demo，帮助理解io与nio区别

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服务器

        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";    // 本地服务器监听的端口    private static final int Listenning_Port = 8888;    // 缓冲区大小    private static final int Buffer_Size = 1024;    // 超时时间,单位毫秒    private static final int TimeOut = 3000;    public static void main(String[] args) throws IOException {        // 创建一个在本地端口进行监听的服务Socket信道.并设置为非阻塞方式        ServerSocketChannel serverChannel = ServerSocketChannel.open();        serverChannel.socket().bind(new InetSocketAddress(Listenning_Port));        serverChannel.configureBlocking(false);        // 创建一个选择器并将serverChannel注册到它上面        Selector selector = Selector.open();        serverChannel.register(selector, SelectionKey.OP_ACCEPT);        while (true) {            // 等待某个信道就绪            if (selector.select(TimeOut) == 0) {                System.out.println(".");                continue;            }            // 获得就绪信道的键迭代器            Iterator<SelectionKey> keyIter = selector.selectedKeys().iterator();            // 使用迭代器进行遍历就绪信道            while (keyIter.hasNext()) {                SelectionKey key = keyIter.next();                // 这种情况是有客户端连接过来,准备一个clientChannel与之通信                if (key.isAcceptable()) {                    SocketChannel clientChannel = ((ServerSocketChannel) key.channel()).accept();                    clientChannel.configureBlocking(false);                    clientChannel.register(selector, SelectionKey.OP_READ,                            ByteBuffer.allocate(Buffer_Size));                }                // 客户端有写入时                if (key.isReadable()) {                    // 获得与客户端通信的信道                    SocketChannel clientChannel = (SocketChannel) key.channel();                    // 得到并重置缓冲区的主要索引值                    ByteBuffer buffer = (ByteBuffer) key.attachment();                    buffer.clear();                    // 读取信息获得读取的字节数                    long bytesRead = clientChannel.read(buffer);                    if (bytesRead == -1) {                        // 没有读取到内容的情况                        clientChannel.close();                    } else {                        // 将缓冲区准备为数据传出状态                        buffer.flip();                        // 将获得字节字符串(使用Charset进行解码)                        String receivedString = Charset                                .forName(LocalCharSetName).newDecoder().decode(buffer).toString();                        // 控制台打印出来                        System.out.println("接收到信息:" + receivedString);                        // 准备发送的文本                        String sendString = "你好,客户端. 已经收到你的信息" + receivedString;                        // 将要发送的字符串编码(使用Charset进行编码)后再进行包装                        buffer = ByteBuffer.wrap(sendString.getBytes(LocalCharSetName));                        // 发送回去                        clientChannel.write(buffer);                        // 设置为下一次读取或是写入做准备                        key.interestOps(SelectionKey.OP_READ | SelectionKey.OP_WRITE);                    }                }                keyIter.remove();            }        }    }}

客户端

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();        // 输出        PrintWriter out = new PrintWriter(outStream, true);        out.println("getPublicKey你好！");        out.flush();        s.shutdownOutput();// 输出结束        // 输入        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);    }}

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