以前一直用的是“ervery thread per
connection”的服務(wù)器端模式，今天試了下NIO非阻塞模式的服務(wù)器。

以前一直用的是“ervery thread per connection”的服務(wù)器端模式，今天試了下NIO非阻塞模式的服務(wù)器。
不過java不能實(shí)現(xiàn)I/O完成端口模型，這點(diǎn)很遺憾。

1. package com.vista.Server;
2. import java.io.IOException;
3. import java.net.InetSocketAddress;
4. import java.net.ServerSocket;
5. import java.nio.ByteBuffer;
6. import java.nio.channels.SelectionKey;
7. import java.nio.channels.Selector;
8. import java.nio.channels.ServerSocketChannel;
9. import java.nio.channels.SocketChannel;
10. import java.util.Iterator;
11. import java.util.LinkedList;
12. import java.util.Set;
13. public class SelectorServer
14. {
15. private static int DEFAULT_SERVERPORT = 6018;//默認(rèn)端口
16. private static int DEFAULT_BUFFERSIZE = 1024;//默認(rèn)緩沖區(qū)大小為1024字節(jié)
17. private ServerSocketChannel channel;
18. private LinkedList<SocketChannel> clients;
19. private Selector readSelector;
20. private ByteBuffer buffer;//字節(jié)緩沖區(qū)
21. private int port;
22. public SelectorServer(int port) throws IOException
23. {
24. this.port = port;
25. this.clients = new LinkedList<SocketChannel>();
26. this.channel = null;
27. this.readSelector = Selector.open();//打開選擇器
28. this.buffer = ByteBuffer.allocate(DEFAULT_BUFFERSIZE);
29. }
30. // 服務(wù)器程序在服務(wù)循環(huán)中調(diào)用sericeClients()方法為已接受的客戶服務(wù)
31. public void serviceClients()throws IOException
32. {
33. Set keys;
34. Iterator it;
35. SelectionKey key;
36. SocketChannel client;
37. // 在readSelector上調(diào)用select()方法，參數(shù)1代表如果調(diào)用select的時(shí)候 那么阻塞最多1秒鐘等待可用的客戶端連接
38. if(readSelector.select(1) > 0)
39. {
40. keys = readSelector.selectedKeys(); // 取得代表端通道的鍵集合
41. it = keys.iterator();
42. // 遍歷，為每一個(gè)客戶服務(wù)
43. while(it.hasNext())
44. {
45. key = (SelectionKey)it.next();
46. if(key.isReadable())
47. { // 如果通道可讀，那么讀此通道到buffer中
48. int bytes;
49. client = (SocketChannel)key.channel();// 取得鍵對(duì)應(yīng)的通道
50. buffer.clear(); // 清空緩沖區(qū)中的內(nèi)容，設(shè)置好position,limit，準(zhǔn)備接受數(shù)據(jù)
51. bytes = client.read(buffer); // 從通道中讀數(shù)據(jù)到緩沖中，返回讀取得字節(jié)數(shù)
52. if(bytes >= 0)
53. {
54. buffer.flip(); // 準(zhǔn)備將緩沖中的數(shù)據(jù)寫回到通道中
55. client.write(buffer); // 數(shù)據(jù)寫回到通道中
56. }
57. else if(bytes < 0)
58. { // 如果返回小于零的值代表讀到了流的末尾
59. clients.remove(client);
60. // 通道關(guān)閉時(shí)，選擇鍵也被取消
61. client.close();
62. }
63. }
64. }
65. }
66. }
67. public void registerClient(SocketChannel client) throws IOException
68. {// 配置和注冊(cè)代表客戶連接的通道對(duì)象
69. client.configureBlocking(false); // 設(shè)置此通道使用非阻塞模式
70. client.register(readSelector, SelectionKey.OP_READ); // 將這個(gè)通道注冊(cè)到選擇器上
71. clients.add(client); //保存這個(gè)通道對(duì)象
72. }
73. public void listen() throws IOException
74. { //服務(wù)器開始監(jiān)聽端口，提供服務(wù)
75. ServerSocket socket;
76. SocketChannel client;
77. channel = ServerSocketChannel.open(); // 打開通道
78. socket = channel.socket(); //得到與通到相關(guān)的socket對(duì)象
79. socket.bind(new InetSocketAddress(port), 10); //將scoket榜定在制定的端口上
80. //配置通到使用非阻塞模式，在非阻塞模式下，可以編寫多道程序同時(shí)避免使用復(fù)雜的多線程
81. channel.configureBlocking(false);
82. try
83. {
84. while(true)
85. {// 與通常的程序不同，這里使用channel.accpet()接受客戶端連接請(qǐng)求，而不是在socket對(duì)象上調(diào)用accept(),這里在調(diào)用accept()方法時(shí)如果通道配置為非阻塞模式,那么accept()方法立即返回null，并不阻塞
86. client = channel.accept();
87. if(client != null)
88. {
89. registerClient(client); // 注冊(cè)客戶信息
90. }
91. serviceClients(); // 為以連接的客戶服務(wù)
92. }
93. }
94. finally
95. {
96. socket.close(); // 關(guān)閉socket，關(guān)閉socket會(huì)同時(shí)關(guān)閉與此socket關(guān)聯(lián)的通道
97. }
98. }
99. public static void main(String[] args) throws IOException
100. {
101. System.out.println(“服務(wù)器啟動(dòng)”);
102. SelectorServer server = new SelectorServer(SelectorServer.DEFAULT_SERVERPORT);
103. server.listen(); //服務(wù)器開始監(jiān)聽端口，提供服務(wù)
104. }
105. }

修改版本：

1. package com.vista.Server;
2. import java.io.BufferedWriter;
3. import java.io.FileInputStream;
4. import java.io.IOException;
5. import java.io.OutputStreamWriter;
6. import java.io.PrintWriter;
7. import java.net.InetSocketAddress;
8. import java.net.ServerSocket;
9. import java.nio.ByteBuffer;
10. import java.nio.CharBuffer;
11. import java.nio.channels.FileChannel;
12. import java.nio.channels.SelectionKey;
13. import java.nio.channels.Selector;
14. import java.nio.channels.ServerSocketChannel;
15. import java.nio.channels.SocketChannel;
16. import java.nio.charset.Charset;
17. import java.nio.charset.CharsetDecoder;
18. import java.util.Iterator;
19. import java.util.LinkedList;
20. import java.util.Set;
21. public class SelectorServer
22. {
23. private static int DEFAULT_SERVERPORT = 6018;//默認(rèn)端口
24. private static int DEFAULT_BUFFERSIZE = 1024;//默認(rèn)緩沖區(qū)大小為1024字節(jié)
25. private static String DEFAULT_CHARSET = “GB2312”;//默認(rèn)碼集
26. private static String DEFAULT_FILENAME = “bigfile.dat”;
27. private ServerSocketChannel channel;
28. private LinkedList<SocketChannel> clients;
29. private Selector selector;//選擇器
30. private ByteBuffer buffer;//字節(jié)緩沖區(qū)
31. private int port;
32. private Charset charset;//字符集
33. private CharsetDecoder decoder;//解碼器
34. public SelectorServer(int port) throws IOException
35. {
36. this.port = port;
37. this.clients = new LinkedList<SocketChannel>();
38. this.channel = null;
39. this.selector = Selector.open();//打開選擇器
40. this.buffer = ByteBuffer.allocate(DEFAULT_BUFFERSIZE);
41. this.charset = Charset.forName(DEFAULT_CHARSET);
42. this.decoder = this.charset.newDecoder();
43. }
44. private class HandleClient
45. {
46. private String strGreeting = “welcome to VistaQQ”;
47. public HandleClient() throws IOException
48. {
49. }
50. public String readBlock()
51. {//讀塊數(shù)據(jù)
52. return this.strGreeting;
53. }
54. public void close()
55. {
56. }
57. }
58. protected void handleKey(SelectionKey key) throws IOException
59. {//處理事件
60. if (key.isAcceptable())
61. { // 接收請(qǐng)求
62. ServerSocketChannel server = (ServerSocketChannel) key.channel();//取出對(duì)應(yīng)的服務(wù)器通道
63. SocketChannel channel = server.accept();
64. channel.configureBlocking(false);
65. channel.register(selector, SelectionKey.OP_READ);//客戶socket通道注冊(cè)讀操作
66. }
67. else if (key.isReadable())
68. { // 讀信息
69. SocketChannel channel = (SocketChannel) key.channel();
70. int count = channel.read(this.buffer);
71. if (count > 0)
72. {
73. this.buffer.flip();
74. CharBuffer charBuffer = decoder.decode(this.buffer);
75. System.out.println(“Client >>” + charBuffer.toString());
76. SelectionKey wKey = channel.register(selector,
77. SelectionKey.OP_WRITE);//為客戶sockt通道注冊(cè)寫操作
78. wKey.attach(new HandleClient());
79. }
80. else
81. {//客戶已經(jīng)斷開
82. channel.close();
83. }
84. this.buffer.clear();//清空緩沖區(qū)
85. }
86. else if (key.isWritable())
87. { // 寫事件
88. SocketChannel channel = (SocketChannel) key.channel();
89. HandleClient handle = (HandleClient) key.attachment();//取出處理者
90. ByteBuffer block = ByteBuffer.wrap(handle.readBlock().getBytes());
91. channel.write(block);
92. // channel.socket().getInputStream().(block);
93. // PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
94. // channel.socket().getOutputStream())), true);
95. // out.write(block.toString());
96. }
97. }
98. public void listen() throws IOException
99. { //服務(wù)器開始監(jiān)聽端口，提供服務(wù)
100. ServerSocket socket;
101. channel = ServerSocketChannel.open(); // 打開通道
102. socket = channel.socket(); //得到與通到相關(guān)的socket對(duì)象
103. socket.bind(new InetSocketAddress(port)); //將scoket榜定在制定的端口上
104. //配置通到使用非阻塞模式，在非阻塞模式下，可以編寫多道程序同時(shí)避免使用復(fù)雜的多線程
105. channel.configureBlocking(false);
106. channel.register(selector, SelectionKey.OP_ACCEPT);
107. try
108. {
109. while(true)
110. {// 與通常的程序不同，這里使用channel.accpet()接受客戶端連接請(qǐng)求，而不是在socket對(duì)象上調(diào)用accept(),這里在調(diào)用accept()方法時(shí)如果通道配置為非阻塞模式,那么accept()方法立即返回null，并不阻塞
111. this.selector.select();
112. Iterator iter = this.selector.selectedKeys().iterator();
113. while(iter.hasNext())
114. {
115. SelectionKey key = (SelectionKey)iter.next();
116. iter.remove();
117. this.handleKey(key);
118. }
119. }
120. }
121. catch(IOException ex)
122. {
123. ex.printStackTrace();
124. }
125. }
126. public static void main(String[] args) throws IOException
127. {
128. System.out.println(“服務(wù)器啟動(dòng)”);
129. SelectorServer server = new SelectorServer(SelectorServer.DEFAULT_SERVERPORT);
130. server.listen(); //服務(wù)器開始監(jiān)聽端口，提供服務(wù)
131. }
132. }