NIO socket
来源:互联网 发布:数控车g71编程实例详解 编辑:程序博客网 时间:2024/05/23 22:28
Java NIO模式的Socket通信,是一种同步非阻塞IO设计模式,它为Reactor模式实现提供了基础。
下面看看,Java实现的一个服务端和客户端通信的例子。
NIO模式的基本原理描述如下:
服务端打开一个通道(ServerSocketChannel),并向通道中注册一个选择器(Selector),这个选择器是与一些感兴趣的操作的标识(SelectionKey,即通过这个标识可以定位到具体的操作,从而进行响应的处理)相关联的,然后基于选择器(Selector)轮询通道(ServerSocketChannel)上注册的事件,并进行相应的处理。
客户端在请求与服务端通信时,也可以向服务器端一样注册(比服务端少了一个SelectionKey.OP_ACCEPT操作集合),并通过轮询来处理指定的事件,而不必阻塞。
下面的例子,主要以服务端为例,而客户端只是简单地发送请求数据和读响应数据。
服务端实现,代码如下所示:
- package org.shirdrn.java.communications.nio;
- 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.util.Iterator;
- import java.util.Set;
- import java.util.logging.Logger;
- /**
- * NIO服务端
- *
- * @author shirdrn
- */
- public class NioTcpServer extends Thread {
- private static final Logger log = Logger.getLogger(NioTcpServer.class.getName());
- private InetSocketAddress inetSocketAddress;
- private Handler handler = new ServerHandler();
- public NioTcpServer(String hostname, int port) {
- inetSocketAddress = new InetSocketAddress(hostname, port);
- }
- @Override
- public void run() {
- try {
- Selector selector = Selector.open(); // 打开选择器
- ServerSocketChannel serverSocketChannel = ServerSocketChannel.open(); // 打开通道
- serverSocketChannel.configureBlocking(false); // 非阻塞
- serverSocketChannel.socket().bind(inetSocketAddress);
- serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT); // 向通道注册选择器和对应事件标识
- log.info("Server: socket server started.");
- while(true) { // 轮询
- int nKeys = selector.select();
- if(nKeys>0) {
- Set<SelectionKey> selectedKeys = selector.selectedKeys();
- Iterator<SelectionKey> it = selectedKeys.iterator();
- while(it.hasNext()) {
- SelectionKey key = it.next();
- if(key.isAcceptable()) {
- log.info("Server: SelectionKey is acceptable.");
- handler.handleAccept(key);
- } else if(key.isReadable()) {
- log.info("Server: SelectionKey is readable.");
- handler.handleRead(key);
- } else if(key.isWritable()) {
- log.info("Server: SelectionKey is writable.");
- handler.handleWrite(key);
- }
- it.remove();
- }
- }
- }
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- /**
- * 简单处理器接口
- *
- * @author shirdrn
- */
- interface Handler {
- /**
- * 处理{@link SelectionKey#OP_ACCEPT}事件
- * @param key
- * @throws IOException
- */
- void handleAccept(SelectionKey key) throws IOException;
- /**
- * 处理{@link SelectionKey#OP_READ}事件
- * @param key
- * @throws IOException
- */
- void handleRead(SelectionKey key) throws IOException;
- /**
- * 处理{@link SelectionKey#OP_WRITE}事件
- * @param key
- * @throws IOException
- */
- void handleWrite(SelectionKey key) throws IOException;
- }
- /**
- * 服务端事件处理实现类
- *
- * @author shirdrn
- */
- class ServerHandler implements Handler {
- @Override
- public void handleAccept(SelectionKey key) throws IOException {
- ServerSocketChannel serverSocketChannel = (ServerSocketChannel)key.channel();
- SocketChannel socketChannel = serverSocketChannel.accept();
- log.info("Server: accept client socket " + socketChannel);
- socketChannel.configureBlocking(false);
- socketChannel.register(key.selector(), SelectionKey.OP_READ);
- }
- @Override
- public void handleRead(SelectionKey key) throws IOException {
- ByteBuffer byteBuffer = ByteBuffer.allocate(512);
- SocketChannel socketChannel = (SocketChannel)key.channel();
- while(true) {
- int readBytes = socketChannel.read(byteBuffer);
- if(readBytes>0) {
- log.info("Server: readBytes = " + readBytes);
- log.info("Server: data = " + new String(byteBuffer.array(), 0, readBytes));
- byteBuffer.flip();
- socketChannel.write(byteBuffer);
- break;
- }
- }
- socketChannel.close();
- }
- @Override
- public void handleWrite(SelectionKey key) throws IOException {
- ByteBuffer byteBuffer = (ByteBuffer) key.attachment();
- byteBuffer.flip();
- SocketChannel socketChannel = (SocketChannel)key.channel();
- socketChannel.write(byteBuffer);
- if(byteBuffer.hasRemaining()) {
- key.interestOps(SelectionKey.OP_READ);
- }
- byteBuffer.compact();
- }
- }
- public static void main(String[] args) {
- NioTcpServer server = new NioTcpServer("localhost", 1000);
- server.start();
- }
- }
客户端实现,代码如下所示:
- package org.shirdrn.java.communications.nio;
- import java.io.IOException;
- import java.net.InetSocketAddress;
- import java.nio.ByteBuffer;
- import java.nio.channels.SocketChannel;
- import java.util.logging.Logger;
- /**
- * NIO客户端
- *
- * @author shirdrn
- */
- public class NioTcpClient {
- private static final Logger log = Logger.getLogger(NioTcpClient.class.getName());
- private InetSocketAddress inetSocketAddress;
- public NioTcpClient(String hostname, int port) {
- inetSocketAddress = new InetSocketAddress(hostname, port);
- }
- /**
- * 发送请求数据
- * @param requestData
- */
- public void send(String requestData) {
- try {
- SocketChannel socketChannel = SocketChannel.open(inetSocketAddress);
- socketChannel.configureBlocking(false);
- ByteBuffer byteBuffer = ByteBuffer.allocate(512);
- socketChannel.write(ByteBuffer.wrap(requestData.getBytes()));
- while (true) {
- byteBuffer.clear();
- int readBytes = socketChannel.read(byteBuffer);
- if (readBytes > 0) {
- byteBuffer.flip();
- log.info("Client: readBytes = " + readBytes);
- log.info("Client: data = " + new String(byteBuffer.array(), 0, readBytes));
- socketChannel.close();
- break;
- }
- }
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- public static void main(String[] args) {
- String hostname = "localhost";
- String requestData = "Actions speak louder than words!";
- int port = 1000;
- new NioTcpClient(hostname, port).send(requestData);
- }
- }
上述实现,NioTcpServer服务线程启动后,监听指定端口,等待客户端请求的到来,然后NioTcpClient客户端进程启动并发送请求数据,服务端接收到请求数据后,响应客户端(将请求的数据作为响应数据写回到客户端通道SocketChannel,并等待客户端处理)。
实际上,客户端和服务端可以采用同样轮询的非阻塞模式来实现,为简单实现在这个例子中我们把客户端角色简化了,而实际上它可能在另一个系统通信中充当服务端角色。
另外,上面对于不同事件是采用非线程的方式来处理,只是简单地调用处理的方法。在实际中,如果存在大量连接、读写请求,可以考虑使用线程池来更大程度地并发处理,提高服务端处理的速度和吞吐量,提升系统性能。
- NIO socket
- NIO socket
- Java NIO 与 Nio Socket
- nio socket 学习
- NIO SSL Socket Server
- NIO的Socket编程
- Java NIO Socket Channel
- java nio socket
- NIO Socket Server DEMO
- NIO Socket学习
- NIO channel Socket通道
- NIO Socket实现文件服务器
- Java NIO Socket通信
- Java NIO Socket通信
- NIO Socket实现文件传输
- JAVA NIO Socket通道
- 学习socket nio
- java nio socket 实例
- 未解决的问题记录——关于easyui中datagrid的冻结列右侧冻结
- Provisional headers are shown
- 设置banner图片居中且有背景
- php解决ajax无法跨域的问题
- python处理csv数据
- NIO socket
- C++ Primer(第五版)练习6.5
- 74. Search a 2D Matrix
- Codeforces 731D 求所有区间的交(树状数组或前缀和)
- 正则表达式(括号)、[中括号]、{大括号}的区别小结
- jquery easyUI ComboTree使用心得
- 《Hibernate》--------单表查询的功能封装
- PHP基础知识(小要点)
- commons-fileUpload组件解决文件上传乱码问题