java NIO经典实例
服务端：
Loader.java
package net.chatroom.server; public class Loader { public static void main(String[] args) { Deamon deamon = new Deamon(9999); new Thread(deamon).start(); } }
Util.java
package net.chatroom.server; import java.nio.charset.Charset; import java.util.HashSet; public class Util { public static Charset charset = Charset.forName("UTF-8"); // 相当于自定义协议格式，与客户端协商好 public static String USER_CONTENT_SPILIT = "#@#"; // 用来记录在线人数，以及昵称 public static HashSet<String> users = new HashSet<String>(); public static String USER_EXIST = "system message: user exist, please change a name"; }
Deamon.java
package net.chatroom.server; import java.io.IOException; import java.net.InetSocketAddress; 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.ArrayList; import java.util.HashSet; import java.util.Iterator; import java.util.List; public class Deamon implements Runnable { private boolean flag = true; private ServerSocketChannel serverChannel = null; private Selector selector = null; /** * 记录进来的所有的客户端连接 * */ private List<SocketChannel> clientChannels = null; public void setFlag(boolean flag) { this.flag = flag; } public Deamon(int port) { try { serverChannel = ServerSocketChannel.open(); serverChannel.socket().bind(new InetSocketAddress(port)); selector = Selector.open(); serverChannel.configureBlocking(false); serverChannel.register(selector, SelectionKey.OP_ACCEPT); this.clientChannels = new ArrayList<SocketChannel>(); System.out.println("Server is listening now..."); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } @Override public void run() { // System.out.println("server listening.."); while (this.flag) { int num = 0; try { //此处select()阻塞了线程 num = selector.select(); } catch (IOException e) { System.out.println("Error while select channel:" + e); } if (num > 0) { Iterator<SelectionKey> it = selector.selectedKeys().iterator(); while (it.hasNext()) { SelectionKey key = it.next(); it.remove(); if (key.isAcceptable()) { // 监听到有新的连接则再注册读操作 this.clientChannels.add(Dealer.accept(selector, serverChannel)); } else if (key.isReadable()) { // 监听到读操作 try { Dealer.read(selector, key, clientChannels); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } try { Thread.sleep(500); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } System.out.println("server to close.."); if (this.serverChannel != null && this.serverChannel.isOpen()) { try { this.serverChannel.close(); } catch (IOException e) { e.printStackTrace(); } } if (this.selector != null && this.selector.isOpen()) { try { this.selector.close(); } catch (IOException e) { e.printStackTrace(); } } } }
Dealer.java
package net.chatroom.server; import java.io.IOException; import java.nio.ByteBuffer; import java.nio.channels.Channel; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.ServerSocketChannel; import java.nio.channels.SocketChannel; import java.rmi.server.Skeleton; import java.util.List; import java.util.Scanner; public class Dealer { public static SocketChannel accept(Selector selector, ServerSocketChannel serverChannel) { SocketChannel channel = null; try { channel = serverChannel.accept(); channel.configureBlocking(false); channel.register(selector, SelectionKey.OP_READ); channel.write(Util.charset.encode("Please input your name.")); } catch (Exception e) { System.out.println("Error while configure socket channel :" + e); if (channel != null) { try { channel.close(); } catch (IOException e1) { e1.printStackTrace(); } } } return channel; } public static void read(Selector selector, SelectionKey selectionkey, List<SocketChannel> clientChannels) throws IOException { SocketChannel socketClientChannel = (SocketChannel) selectionkey .channel(); ByteBuffer buffer = ByteBuffer.allocateDirect(6 * 1024); StringBuilder content = new StringBuilder(); int num = 0; try { // 将客户端发上来的消息读到buffer //循环将通道中数据读入buffer while (socketClientChannel.read(buffer) > 0) { buffer.flip();// 切换成读 content.append(Util.charset.decode(buffer)); } System.out.println("num:" + num); System.out.println("Server is listening from client :" + socketClientChannel.getRemoteAddress() + " data rev is: " + content); } catch (IOException e) { /** * 如果出现异常，则需要关闭连接。故把num设置为-1，用下面的关闭逻辑来关闭channel */ num = -1; } if (num >= 0) { if (content.length() > 0) { String[] arrayContent = content.toString().split( Util.USER_CONTENT_SPILIT); // 注册用户 if (arrayContent != null && arrayContent.length == 1) { String name = arrayContent[0]; if (Util.users.contains(name)) { socketClientChannel.write(Util.charset .encode(Util.USER_EXIST)); } else { Util.users.add(name); int onlineNum = clientChannels.size(); String message = "welcome " + name + " to chat room! Online numbers:" + onlineNum; BroadCast2(clientChannels, null, message); } } // 注册完了，发送消息 else if (arrayContent != null && arrayContent.length > 1) { String name = arrayContent[0]; String message = content.substring(name.length() + Util.USER_CONTENT_SPILIT.length()); message = name + " say: " + message; if (Util.users.contains(name)) { // 不回发给发送此内容的客户端 BroadCast2(clientChannels, socketClientChannel, message); } } // /** // * 把读到的数据原封不动的下发给客户端 // */ // int length = clientChannels.size(); // for (int index = 0; index < length; index++) { // // 循环所有的客户端连接，下发数据 // buffer.flip(); // try { // // 将buffer里的数据再下发给客户端的通道 // clientChannels.get(index).write(buffer); // } catch (IOException e) { // e.printStackTrace(); // } // } } } else { /** * 如果未读到数据，对方关闭了SocketChannel 所以服务器这边也要关闭 */ try { socketClientChannel.close(); int length = clientChannels.size(); for (int index = 0; index < length; index++) { if (clientChannels.get(index).equals(socketClientChannel)) { // 移除当前接受的通道 clientChannels.remove(index); break; } } } catch (IOException e) { e.printStackTrace(); } } } // TODO 要是能检测下线，就不用这么统计了 public static int OnlineNum(Selector selector) { int res = 0; for (SelectionKey key : selector.keys()) { Channel targetchannel = key.channel(); if (targetchannel instanceof SocketChannel) { res++; } } return res; } public void BroadCast(Selector selector, SocketChannel except, String content) throws IOException { // 广播数据到所有的SocketChannel中 for (SelectionKey key : selector.keys()) { Channel targetchannel = key.channel(); // 如果except不为空，不回发给发送此内容的客户端 if (targetchannel instanceof SocketChannel && targetchannel != except) { SocketChannel dest = (SocketChannel) targetchannel; dest.write(Util.charset.encode(content)); } } } public static void BroadCast2(List<SocketChannel> socketChannels, SocketChannel except, String content) throws IOException { for (SocketChannel socketChannel : socketChannels) { if (!socketChannel.equals(except)) { // 除了自己，其它通道都通知 socketChannel.write(Util.charset.encode(content)); } } } }
客户端：
Loader.java
package net.chatroom.client; import java.util.Scanner; import net.chatroom.server.Util; public class Loader { public static void main(String[] args) { String name = ""; Deamon deamon = new Deamon("127.0.0.1", 9999); new Thread(deamon).start(); // 在主线程中 从键盘读取数据输入到服务器端 Scanner scan = new Scanner(System.in); while (scan.hasNextLine()) { String line = scan.nextLine(); if ("".equals(line)) continue; // 不允许发空消息 if ("".equals(name)) { name = line; line = name + Util.USER_CONTENT_SPILIT; } else { line = name + Util.USER_CONTENT_SPILIT + line; } deamon.chancelToWrite(Util.charset.encode(line));// sc既能写也能读，这边是写 } } }
Deamon.java
package net.chatroom.client; import java.io.IOException; import java.net.InetSocketAddress; import java.nio.Buffer; import java.nio.ByteBuffer; import java.nio.channels.SelectionKey; import java.nio.channels.Selector; import java.nio.channels.SocketChannel; import java.util.Iterator; import java.util.Scanner; import net.chatroom.server.Util; public class Deamon implements Runnable { /** * 选择器，用于监听注册在上面的SocketChannel的状态 */ private Selector selector = null; /** * SocketChannel 用户发送和接受数据的信道 */ private SocketChannel channel = null; /** * 运行标识。在线程里此标识为false的时候会推出线程 * 该属性在ExitCommandListener里通过调用setFlag方法修改，用于通知线程用户要求退出的程序 */ private boolean flag = true; public void setFlag(boolean flag) { this.flag = flag; } public Deamon(String address, int port) { try { channel = SocketChannel.open(new InetSocketAddress(address, port)); channel.configureBlocking(false); selector = Selector.open(); // 客户端直接注册读和写操作 channel.register(selector, SelectionKey.OP_READ | SelectionKey.OP_WRITE); } catch (IOException e) { e.printStackTrace(); } } public void chancelToWrite(ByteBuffer buffer){ try { channel.write(buffer); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } @Override public void run() { System.out.println("client run.."); while (this.flag) { /** * 如果可以继续执行，则在循环体内循环执行监听选择操作 */ int num = 0; try { /** * 得到处于可读或者可写状态的SocketChannel对象的个数 */ // 客户端的select()并不阻塞线程,是因为客户端一启动就是SelectionKey.OP_WRITE状态 // System.out.println("client select.."); num = this.selector.select(); // System.out.println("client num:"+num); } catch (IOException e) { /** * 如果出现异常，则此处应该加上日志打印，然后跳出循环,执行循环体下面的释放资源操作 */ break; } if (num > 0) { /** * 如果有多个SocketChannel处于可读或者可写状态，则轮询注册在Selector上面的SelectionKey */ Iterator<SelectionKey> keys = selector.selectedKeys() .iterator(); while (keys.hasNext()) { SelectionKey key = keys.next(); /** * 此步操作用于删除该SelectionKey的被选中状态 */ keys.remove(); if (key.isReadable()) { System.out.println("client isReadable.."); /** * 如果是读操作，则调用读操作的处理逻辑 */ try { Dealer.read((SocketChannel) key.channel()); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } else if (key.isWritable()) { //客户端的写状态是一直就绪的 // System.out.println("client isWritable.."); /** * 如果是写操作，则调用写操作的处理逻辑 */ // Dealer.write((SocketChannel) key.channel()); } } } /*取消关注，多用在多线程的时候 * key.interestOps(key.interestOps() & (~SelectionKey.OP_READ)); * * 增加关注 * key.interestOps(key.interestOps() | SelectionKey.OP_READ); * */ try { Thread.sleep(500); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (this.channel != null && this.channel.isOpen()) { /** * 关闭SocketChannel */ try { this.channel.close(); } catch (IOException e) { e.printStackTrace(); } } if (this.selector != null && this.selector.isOpen()) { /** * 关闭Selector选择器 */ try { this.selector.close(); } catch (IOException e) { e.printStackTrace(); } } } }
Dealer.java
package net.chatroom.client; import java.io.IOException; import java.nio.ByteBuffer; import java.nio.channels.SocketChannel; import net.chatroom.server.Util; public class Dealer { /** * 从SocketChannel中读取信息 * * @param channel * @throws IOException */ public static void read(SocketChannel channel) throws IOException { /** * 初始化缓冲区 */ ByteBuffer buffer = ByteBuffer.allocateDirect(6 * 1024); /** * 读到的字节数 */ int num = 0; String content = ""; while ((num = channel.read(buffer)) > 0) { buffer.flip(); content += Util.charset.decode(buffer); } //若系统发送通知名字已经存在，则需要换个昵称 if(Util.USER_EXIST.equals(content)) { // name = ""; System.out.println("name has exists."); } System.out.println(content); } /** * 想SocketChannel中写入数据 * * @param channel */ public static void write(SocketChannel channel) { // /** // * 从消息队列中获取要发送的消息 // */ // String msg = MsgQueue.getInstance().get(); // if (msg == null) { // /** // * 如果消息队列中没有要发送的消息，则返回。 // */ // return; // } // /** // * 初始化缓冲区 // */ // ByteBuffer buffer = ByteBuffer.allocateDirect(6 * 1024); // // /** // * 把消息放到缓冲区中 // */ // buffer.put(msg.getBytes()); // // /** // * 重置缓冲区指针 // */ // buffer.flip(); // try { // /** // * 把缓冲区中的数据写到SocketChannel里 // */ // channel.write(buffer); // } catch (IOException e) { // e.printStackTrace(); // } } }