使用Java NIO提高服务端程序的性能

1 // ==================== Program Discription =====================
2 // 程序名称：示例12-14 : SocketChannelDemo.java
3 // 程序目的：学习Java NIO#SocketChannel
4 // ==============================================================
5 
6 
7 import java.nio.ByteBuffer;
8 import java.nio.channels.ServerSocketChannel;
9 import java.nio.channels.SocketChannel;
10 import java.nio.channels.Selector;
11 import java.nio.channels.SelectionKey;
12 import java.nio.channels.SelectableChannel;
13 
14 import java.net.Socket;
15 import java.net.ServerSocket;
16 import java.net.InetSocketAddress;
17 import java.util.Iterator;
18
19 public class SocketChannelDemo

20 
21 {
22 public static int PORT_NUMBER = 23;//监听端口
23 ServerSocketChannel serverChannel;
24 ServerSocket serverSocket ;
25 Selector selector ;
26 private ByteBuffer buffer = ByteBuffer.allocateDirect (1024);
27 
28 public static void main (String [] args)
29 throws Exception
30 {
31 SocketChannelDemo server=new SocketChannelDemo();
32 server.init(args);
33 server.startWork();
34 }
35 
36 
37 public void init (String [] argv)throws Exception
38 {
39 int port = PORT_NUMBER;
40 
41 if (argv.length > 0) { 
42 port = Integer.parseInt (argv [0]);
43 }
44 
45 System.out.println ("Listening on port " + port);
46 
47 // 分配一个ServerSocketChannel
48 serverChannel = ServerSocketChannel.open();
49 // 从ServerSocketChannel里获得一个对应的Socket
50 serverSocket = serverChannel.socket();
51 // 生成一个Selector
52 selector = Selector.open();
53 
54 // 把Socket绑定到端口上
55 serverSocket.bind (new InetSocketAddress (port));
56 //serverChannel为非bolck
57 serverChannel.configureBlocking (false);
58 
59 // 通过Selector注册ServerSocetChannel
60 serverChannel.register (selector, SelectionKey.OP_ACCEPT); 
61 
62 }
63 
64 public void startWork()throws Exception

65 
66 {
67 while (true) {
68 
69 int n = selector.select();//获得IO准备就绪的channel数量
70 
71 if (n == 0) {
72 continue; // 没有channel准备就绪，继续执行
73 }
74 
75 // 用一个iterator返回Selector的selectedkeys
76 Iterator it = selector.selectedKeys().iterator();
77 
78 // 处理每一个SelectionKey
79 while (it.hasNext()) {
80 SelectionKey key = (SelectionKey) it.next();
81
82 // 判断是否有新的连接到达
83 if (key.isAcceptable()) {
84　　　　　　　　　　　//返回SelectionKey的ServerSocketChannel
85 ServerSocketChannel server =
(ServerSocketChannel) key.channel();
86 SocketChannel channel = server.accept();
87 
88 registerChannel (selector, channel,
89 SelectionKey.OP_READ);
90 
91 doWork (channel);
92 }
93 
94 // 判断是否有数据在此channel里需要读取
95 if (key.isReadable()) {
96 
97 processData (key);
98 
99 }
100 
101 //删除 selectedkeys
102 it.remove();
103 }
104 }
105 }
106 protected void registerChannel (Selector selector,
107 SelectableChannel channel, int ops)
108 throws Exception
109 {

110 if (channel == null) {
111 return; 
112 }
113 
114 
115 channel.configureBlocking (false);
116 
117 channel.register (selector, ops);
118 }
119 
120 //处理接收的数据
121 protected void processData (SelectionKey key)
122 throws Exception
123 {
124 
125 
126 SocketChannel socketChannel = (SocketChannel) key.channel();
127 int count;
128 
129 buffer.clear(); // 清空buffer
130 
131 // 读取所有的数据
132 while ((count = socketChannel.read (buffer)) > 0) {
133 buffer.flip(); 
134
135 // send the data, don′t assume it goes all at once
136 while (buffer.hasRemaining())
137 {
138 //如果收到回车键，则在返回的字符前增加[echo]$字样
139 if(buffer.get()==(char)13)
140 {
141 buffer.clear();
142 buffer.put("[echo]___FCKpd___0quot;.getBytes());
143 buffer.flip();
144 
145 }
146 socketChannel.write (buffer);//在Socket里写数据
147 }
148 
149 buffer.clear(); // 清空buffer
150 }
151 
152 if (count < 0) {
153 // count<0，说明已经读取完毕
154 socketChannel.close();

155 }
156 }
157 
158 
159 private void doWork (SocketChannel channel)throws Exception
160 {
161 buffer.clear();
162 buffer.put ("
Hello,I am working,please input some thing,and i will echo to you!
[echo] 
___FCKpd___0quot;.getBytes());
163 buffer.flip();
164 channel.write (buffer);
165 }
166 
167 }