【java网络编程】之四

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	}