[JavaEE] NIO与IO的区别

/**
*
* @author Administrator
* @version
*/

public class NBTest {

/** Creates new NBTest */
public NBTest()
{
}

public void startServer() throws Exception
{
int channels = 0;
int nKeys = 0;
int currentSelector = 0;

//使用Selector
Selector selector = Selector.open();

//建立Channel 并绑定到9000端口
ServerSocketChannel ssc = ServerSocketChannel.open();
InetSocketAddress address = new InetSocketAddress(InetAddress.getLocalHost(),9000);

ssc.socket().bind(address);

//使设定non-blocking的方式。
ssc.configureBlocking(false);

//向Selector注册Channel及我们有兴趣的事件
SelectionKey s = ssc.register(selector, SelectionKey.OP_ACCEPT);
printKeyInfo(s);

while(true) //不断的轮询
{
debug("NBTest: Starting select");

//Selector通过select方法通知我们我们感兴趣的事件发生了。
nKeys = selector.select();
//如果有我们注册的事情发生了，它的传回值就会大于0
if(nKeys > 0)
{
debug("NBTest: Number of keys after select
operation: " +nKeys);

//Selector传回一组SelectionKeys
//我们从这些key中的channel()方法中取得我们刚刚注册的channel。
Set selectedKeys = selector.selectedKeys();
Iterator i = selectedKeys.iterator();
while(i.hasNext())
{
s = (SelectionKey) i.next();
printKeyInfo(s);
debug("NBTest: Nr Keys in selector: "
+selector.keys().size());

//一个key被处理完成后，就都被从就绪关键字（ready keys）列表中除去
i.remove();
if(s.isAcceptable())
{
// 从channel()中取得我们刚刚注册的channel。
Socket socket = ((ServerSocketChannel)s.channel()).accept().socket();
SocketChannel sc = socket.getChannel();

sc.configureBlocking(false);
sc.register(selector, SelectionKey.OP_READ
|SelectionKey.OP_WRITE);
System.out.println(++channels);
}
else
{
debug("NBTest: Channel not acceptable");
}
}
}
else
{
debug("NBTest: Select finished without any
keys.");
}

}

}

private static void debug(String s)
{
System.out.println(s);
}

private static void printKeyInfo(SelectionKey sk)
{
String s = new String();

s = "Att: " + (sk.attachment() == null
? "no" : "yes");
s += ", Read: " + sk.isReadable();
s += ", Acpt: " + sk.isAcceptable();
s += ", Cnct: " + sk.isConnectable();
s += ", Wrt: " + sk.isWritable();
s += ", Valid: " + sk.isValid();
s += ", Ops: " + sk.interestOps();
debug(s);
}

/**
* @param args the command line arguments
*/
public static void main (String args[])
{
NBTest nbTest = new NBTest();
try
{
nbTest.startServer();
}
catch(Exception e)
{
e.printStackTrace();
}
}

}