NIO Socket非阻塞模式代码示例

jdk供的无阻塞I/O（NIO）有效解决了多线程服务器存在的线程开销问题，但在使用上略显得复杂一些。在NIO中使用多线程，主要目的已不是为了应对每个客户端请求而分配独立的服务线程，而是通过多线程充分使用用多个CPU的处理能力和处理中的等待时间，达到提高服务能力的目的。
从最简单的Hello World开始，client多线程请求server端，server接收client的名字，并返回Hello! ＋名字的字符格式给client。当然实际应用并不这么简单，实际可能是访问文件或者数据库获取信息返回给client。非阻塞的NIO有何神秘之处？代码：

1)server端代码

Java代码

1. /**
2. *
3. *@authorJeff
4. *
5. */
6. publicclassHelloWorldServer{
8. staticintBLOCK=1024;
9. staticStringname="";
10. protectedSelectorselector;
11. protectedByteBufferclientBuffer=ByteBuffer.allocate(BLOCK);
12. protectedCharsetDecoderdecoder;
13. staticCharsetEncoderencoder=Charset.forName("GB2312").newEncoder();
15. publicHelloWorldServer(intport)throwsIOException{
16. selector=this.getSelector(port);
17. Charsetcharset=Charset.forName("GB2312");
18. decoder=charset.newDecoder();
19. }
21. //获取Selector
22. protectedSelectorgetSelector(intport)throwsIOException{
23. ServerSocketChannelserver=ServerSocketChannel.open();
24. Selectorsel=Selector.open();
25. server.socket().bind(newInetSocketAddress(port));
26. server.configureBlocking(false);
27. server.register(sel,SelectionKey.OP_ACCEPT);
28. returnsel;
29. }
31. //监听端口
32. publicvoidlisten(){
33. try{
34. for(;;){
35. selector.select();
36. Iteratoriter=selector.selectedKeys().iterator();
37. while(iter.hasNext()){
38. SelectionKeykey=(SelectionKey)iter.next();
39. iter.remove();
40. process(key);
41. }
42. }
43. }catch(IOExceptione){
44. e.printStackTrace();
45. }
46. }
48. //处理事件
49. protectedvoidprocess(SelectionKeykey)throwsIOException{
50. if(key.isAcceptable()){//接收请求
51. ServerSocketChannelserver=(ServerSocketChannel)key.channel();
52. SocketChannelchannel=server.accept();
53. //设置非阻塞模式
54. channel.configureBlocking(false);
55. channel.register(selector,SelectionKey.OP_READ);
56. }elseif(key.isReadable()){//读信息
57. SocketChannelchannel=(SocketChannel)key.channel();
58. intcount=channel.read(clientBuffer);
59. if(count>0){
60. clientBuffer.flip();
61. CharBuffercharBuffer=decoder.decode(clientBuffer);
62. name=charBuffer.toString();
63. //System.out.println(name);
64. SelectionKeysKey=channel.register(selector,
65. SelectionKey.OP_WRITE);
66. sKey.attach(name);
67. }else{
68. channel.close();
69. }
71. clientBuffer.clear();
72. }elseif(key.isWritable()){//写事件
73. SocketChannelchannel=(SocketChannel)key.channel();
74. Stringname=(String)key.attachment();
76. ByteBufferblock=encoder.encode(CharBuffer
77. .wrap("Hello!"+name));
80. channel.write(block);
82. //channel.close();
84. }
85. }
87. publicstaticvoidmain(String[]args){
88. intport=8888;
89. try{
90. HelloWorldServerserver=newHelloWorldServer(port);
91. System.out.println("listeningon"+port);
93. server.listen();
95. }catch(IOExceptione){
96. e.printStackTrace();
97. }
98. }
99. }

server主要是读取client发过来的信息，并返回一条信息

2)client端代码

Java代码

2. /**
3. *
4. *@authorJeff
5. *
6. */
7. publicclassHelloWorldClient{
9. staticintSIZE=10;
10. staticInetSocketAddressip=newInetSocketAddress("localhost",8888);
11. staticCharsetEncoderencoder=Charset.forName("GB2312").newEncoder();
13. staticclassMessageimplementsRunnable{
14. protectedStringname;
15. Stringmsg="";
17. publicMessage(Stringindex){
18. this.name=index;
19. }
21. publicvoidrun(){
22. try{
23. longstart=System.currentTimeMillis();
24. //打开Socket通道
25. SocketChannelclient=SocketChannel.open();
26. //设置为非阻塞模式
27. client.configureBlocking(false);
28. //打开选择器
29. Selectorselector=Selector.open();
30. //注册连接服务端socket动作
31. client.register(selector,SelectionKey.OP_CONNECT);
32. //连接
33. client.connect(ip);
34. //分配内存
35. ByteBufferbuffer=ByteBuffer.allocate(8*1024);
36. inttotal=0;
38. _FOR:for(;;){
39. selector.select();
40. Iteratoriter=selector.selectedKeys().iterator();
42. while(iter.hasNext()){
43. SelectionKeykey=(SelectionKey)iter.next();
44. iter.remove();
45. if(key.isConnectable()){
46. SocketChannelchannel=(SocketChannel)key
47. .channel();
48. if(channel.isConnectionPending())
49. channel.finishConnect();
50. channel
51. .write(encoder
52. .encode(CharBuffer.wrap(name)));
54. channel.register(selector,SelectionKey.OP_READ);
55. }elseif(key.isReadable()){
56. SocketChannelchannel=(SocketChannel)key
57. .channel();
58. intcount=channel.read(buffer);
59. if(count>0){
60. total+=count;
61. buffer.flip();
63. while(buffer.remaining()>0){
64. byteb=buffer.get();
65. msg+=(char)b;
67. }
69. buffer.clear();
70. }else{
71. client.close();
72. break_FOR;
73. }
74. }
75. }
76. }
77. doublelast=(System.currentTimeMillis()-start)*1.0/1000;
78. System.out.println(msg+"usedtime:"+last+"s.");
79. msg="";
80. }catch(IOExceptione){
81. e.printStackTrace();
82. }
83. }
84. }
86. publicstaticvoidmain(String[]args)throwsIOException{
88. Stringnames[]=newString[SIZE];
90. for(intindex=0;index<SIZE;index++){
91. names[index]="jeff["+index+"]";
92. newThread(newMessage(names[index])).start();
93. }
95. }
96. }