１NIO 设计背后的基石：反应器模式，用于事件多路分离和分派的体系结构模式。
反应器模式的核心功能如下：
将事件多路分用
将事件分派到各自相应的事件处理程序
NIO 的非阻塞 I/O 机制是围绕 选择器和 通道构建的。 Channel 类表示服务器和客户机之间的
一种通信机制。Selector 类是 Channel 的多路复用器。 Selector 类将传入客户机请求多路分
用并将它们分派到各自的请求处理程序。
通道(Channel 类)：表示服务器和客户机之间的一种通信机制。
选择器(Selector类)：是 Channel 的多路复用器。Selector 类将传入的客户机请求多路分用并将它们
分派到各自的请求处理程序。
简单的来说：
NIO是一个基于事件的IO架构，最基本的思想就是：有事件我通知你，你再去做你的事情．
而且NIO的主线程只有一个，不像传统的模型，需要多个线程以应对客户端请求，也减轻
了JVM的工作量。
当Channel注册至Selector以后，经典的调用方法如下：
while (somecondition) {
int n = selector.select(TIMEOUT);
if (n == 0)
continue;
for (Iterator iter = selector.selectedKeys().iterator(); iter
.hasNext();) {
if (key.isAcceptable())
doAcceptable(key);
if (key.isConnectable())
doConnectable(key);
if (key.isValid() && key.isReadable())
doReadable(key);
if (key.isValid() && key.isWritable())
doWritable(key);
iter.remove();
}
}
nio中取得事件通知，就是在selector的select事件中完成的。在selector事件时有一个线程
向操作系统询问，selector中注册的Channel&&SelectionKey的键值对的各种事件是否有发生，
如果有则添加到selector的selectedKeys属性Set中去，并返回本次有多少个感兴趣的事情发生。
如果发现这个值>0，表示有事件发生，马上迭代selectedKeys中的SelectionKey，
根据Key中的表示的事件，来做相应的处理。
实际上，这段说明表明了异步socket的核心，即异步socket不过是将多个socket的调度（或者还有他们的线程调度）
全部交给操作系统自己去完成，异步的核心Selector，不过是将这些调度收集、分发而已。
eleven_vv 回复于：2009-03-27 19:17:09
附上一个简单的例子
采用MINA进行socket开发，一般步骤如下：
1：
server:
IoAcceptor acceptor = new SocketAcceptor(); //建立client接收器
or client:
SocketConnector connector = new SocketConnector(); //建立一个连接器
2：server的属性配置：
SocketAcceptorConfig cfg = new SocketAcceptorConfig();
cfg.setReuseAddress(true);
cfg.getFilterChain().addLast(
"codec",
new ProtocolCodecFilter( new ObjectSerializationCodecFactory() ) ); //对象序列化 codec factory
cfg.getFilterChain().addLast( "logger", new LoggingFilter() );
3：绑定address和business logic
server:
acceptor.bind(
new InetSocketAddress( SERVER_PORT ),
new ServerSessionHandler( ), cfg ); // 绑定address和handler
client:
connector.connect(new InetSocketAddress( HOSTNAME, PORT ),
new ClientSessionHandler(msg), cfg );
下面的这个简单的example演示client和server传递object的过程：
Message.java
public class Message implements Serializable {
private int type;
private int status;
private String msgBody;
public Message(int type, int status, String msgBody)
{
this.type = type;
this.status = status;
this.msgBody = msgBody;
}
public String getMsgBody() {
return msgBody;
}
public void setMsgBody(String msgBody) {
this.msgBody = msgBody;
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public int getType() {
return type;
}
public void setType(int type) {
this.type = type;
}
}
Client.java
public class Client
{
private static final String HOSTNAME = "localhost";
private static final int PORT = 8080;
private static final int CONNECT_TIMEOUT = 30; // seconds
public static void main( String[] args ) throws Throwable
{
SocketConnector connector = new SocketConnector();
// Configure the service.
SocketConnectorConfig cfg = new SocketConnectorConfig();
cfg.setConnectTimeout( CONNECT_TIMEOUT );
cfg.getFilterChain().addLast(
"codec",
new ProtocolCodecFilter( new ObjectSerializationCodecFactory() ) );
cfg.getFilterChain().addLast( "logger", new LoggingFilter() );
IoSession session;
Message msg = new Message(0,1,"hello");
connector.connect(new InetSocketAddress( HOSTNAME, PORT ),
new ClientSessionHandler(msg), cfg );
}
}
ClientSessionHandler.java
public class ClientSessionHandler extends IoHandlerAdapter
{
private Object msg;
public ClientSessionHandler(Object msg)
{
this.msg = msg;
}
public void sessionOpened( IoSession session )
{
session.write(this.msg);
}
public void messageReceived( IoSession session, Object message )
{
System.out.println("in messageReceived!");
Message rm = (Message ) message;
SessionLog.debug(session, rm.getMsgBody());
System.out.println("message is: " + rm.getMsgBody());
session.write(rm);
}
public void exceptionCaught( IoSession session, Throwable cause )
{
session.close();
}
}
Server.java
public class Server
{
private static final int SERVER_PORT = 8080;
public static void main( String[] args ) throws Throwable
{
IoAcceptor acceptor = new SocketAcceptor();
// Prepare the service configuration.
SocketAcceptorConfig cfg = new SocketAcceptorConfig();
cfg.setReuseAddress( true );
cfg.getFilterChain().addLast(
"codec",
new ProtocolCodecFilter( new ObjectSerializationCodecFactory() ) );
cfg.getFilterChain().addLast( "logger", new LoggingFilter() );
acceptor.bind(
new InetSocketAddress( SERVER_PORT ),
new ServerSessionHandler( ), cfg );
System.out.println( "The server Listening on port " + SERVER_PORT );
}
}
ServerSessionHandler.java
public class ServerSessionHandler extends IoHandlerAdapter
{
public void sessionOpened( IoSession session )
{
// set idle time to 60 seconds
session.setIdleTime( IdleStatus.BOTH_IDLE, 60 );
session.setAttribute("times",new Integer(0));
}
public void messageReceived( IoSession session, Object message )
{
System.out.println("in messageReceived");
int times = ((Integer)(session.getAttribute("times"))).intValue();
System.out.println("tiems = " + times);
// communicate 30 times,then close the session.
if (times < 30)
{
times++;
session.setAttribute("times", new Integer(times));
Message msg;
msg = (Message) message;
msg.setMsgBody("in server side: " + msg.getMsgBody());
System.out.println("begin send msg: " + msg.getMsgBody());
session.write(msg);
}
else
{
session.close();
}
}
public void sessionIdle( IoSession session, IdleStatus status )
{
SessionLog.info( session, "Disconnecting the idle." );
// disconnect an idle client
session.close();
}
public void exceptionCaught( IoSession session, Throwable cause )
{
// close the connection on exceptional situation
session.close();
}
}
eleven_vv 回复于：2009-03-27 19:17:54
SSL加密传输 加上SSlFilter过滤器
Client 端
connectorSSLFilter = new SSLFilter(BogusSSLContextFactory
.getInstance(true));
connectorSSLFilter.setUseClientMode(true);
connector.getFilterChain().addLast("sslFilter", connectorSSLFilter);
Server
SSLFilter sslFilter = new SSLFilter(BogusSSLContextFactory
.getInstance(true));
chain.addLast("sslFilter", sslFilter);
eleven_vv 回复于：2009-03-27 19:23:23
附上 SSLcontext
public class BogusSSLContextFactory {
/**
* Protocol to use.
*/
private static final String PROTOCOL = "TLS";
private static final String KEY_MANAGER_FACTORY_ALGORITHM;
static {
String algorithm = Security
.getProperty("algorithm");
if (algorithm == null) {
algorithm = "SunX509";
}
KEY_MANAGER_FACTORY_ALGORITHM = algorithm;
}
/**
* Bougus Server certificate keystore file name.
*/
private static final String BOGUS_KEYSTORE = "bogus.cert";
// NOTE: The keystore was generated using keytool:
// keytool -genkey -alias bogus -keysize 512 -validity 3650
// -keyalg RSA -dname "CN=bogus.com, OU=XXX CA,
// O=Bogus Inc, L=Stockholm, S=Stockholm, C=SE"
// -keypass boguspw -storepass boguspw -keystore bogus.cert
/**
* Bougus keystore password.
*/
private static final char[] BOGUS_PW = { 'b', 'o', 'g', 'u', 's', 'p', 'w' };
private static SSLContext serverInstance = null;
private static SSLContext clientInstance = null;
/**
* Get SSLContext singleton.
*
* @return SSLContext
* @throws java.security.GeneralSecurityException
*
*/
public static SSLContext getInstance(boolean server)
throws GeneralSecurityException {
SSLContext retInstance = null;
if (server) {
if (serverInstance == null) {
synchronized (BogusSSLContextFactory.class) {
if (serverInstance == null) {
try {
serverInstance = createBougusServerSSLContext();
} catch (Exception ioe) {
throw new GeneralSecurityException(
"Can't create Server SSLContext:" + ioe);
}
}
}
}
retInstance = serverInstance;
} else {
if (clientInstance == null) {
synchronized (BogusSSLContextFactory.class) {
if (clientInstance == null) {
clientInstance = createBougusClientSSLContext();
}
}
}
retInstance = clientInstance;
}
return retInstance;
}
private static SSLContext createBougusServerSSLContext()
throws GeneralSecurityException, IOException {
// Create keystore
KeyStore ks = KeyStore.getInstance("JKS");
InputStream in = null;
try {
in = BogusSSLContextFactory.class
.getResourceAsStream(BOGUS_KEYSTORE);
ks.load(in, BOGUS_PW);
} finally {
if (in != null) {
try {
in.close();
} catch (IOException ignored) {
}
}
}
// Set up key manager factory to use our key store
KeyManagerFactory kmf = KeyManagerFactory
.getInstance(KEY_MANAGER_FACTORY_ALGORITHM);
kmf.init(ks, BOGUS_PW);
// Initialize the SSLContext to work with our key managers.
SSLContext sslContext = SSLContext.getInstance(PROTOCOL);
sslContext.init(kmf.getKeyManagers(),
BogusTrustManagerFactory.X509_MANAGERS, null);
return sslContext;
}
private static SSLContext createBougusClientSSLContext()
throws GeneralSecurityException {
SSLContext context = SSLContext.getInstance(PROTOCOL);
context.init(null, BogusTrustManagerFactory.X509_MANAGERS, null);
return context;
}
}
eleven_vv 回复于：2009-03-28 00:28:32
申请加精
ruknow 回复于：2009-03-29 10:54:20
这个要顶一下:em17:
bbs_currency 回复于：2009-03-30 10:54:11
看着累。:em17:
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