import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
public class TCP { ServerSocketChannel socketChannel;
Selector selector;
int port = 8778;
String[] opsName=new String[17];
public TCP(){
opsName[SelectionKey.OP_ACCEPT]="OP_ACCEPT";
opsName[SelectionKey.OP_CONNECT]="OP_CONNECT";
opsName[SelectionKey.OP_READ]="OP_READ";
opsName[SelectionKey.OP_WRITE]="OP_WRITE";
try {
socketChannel=ServerSocketChannel.open();
socketChannel.configureBlocking(false);
socketChannel.socket().setReuseAddress(true);
socketChannel.socket().bind(new InetSocketAddress(port));
selector=Selector.open();
System.out.println(socketChannel.hashCode());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void start(){
try {
socketChannel.register(selector, SelectionKey.OP_ACCEPT);
} catch (ClosedChannelException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
System.out.println("server start port "+port);
while(true){
int n;
try {
System.out.print("wait...");
n = selector.select(60000);
System.out.println(n);
if(n<=0)continue;
Iterator<SelectionKey> it = selector.selectedKeys().iterator();
while(it.hasNext()){
SelectionKey key = it.next();
it.remove();
System.out.println("key:"+opsName[key.interestOps()]+","+key.channel().hashCode());
if(key.isReadable()){
System.out.println(key.hashCode()+" isReadable");
socketChannel.accept().register(selector, SelectionKey.OP_READ);
//问题2:socketChannel 与 (SocketChannel)socketChannel.accept() 这两个channel什么区别
}
else if(key.isAcceptable()){
//问题1:当一个客户端连接进来时,为什么这句话会一直重复地打印
System.out.println(key.hashCode()+" accepted");
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} public static void main(String[] args) {
TCP tcp = new TCP();
tcp.start();
}
}
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要remove掉,API里面有说明,待会再贴给你看
//问题2:socketChannel 与 (SocketChannel)socketChannel.accept() 这两个channel什么区别
一个是ServerSocket用来连接客户端的,一个是已经连接上了客户端的需要read或write的
while(it.hasNext()){
SelectionKey key = it.next();
it.remove();...
这里肯定了,你判断的条件是 else if(key.isAcceptable()),也就是如果客户端连接来了就会打印。连接了后你应该再把服务端变成可读的,但是你什么都没写。也就是一直只是可接受的。所以其他的if没有执行。可以看下面代码: public class server {
ServerSocketChannel ssc; public void start() {
try {
Selector selector = Selector.open();
ServerSocketChannel ssc = ServerSocketChannel.open();
ssc.configureBlocking(false);
ServerSocket ss = ssc.socket();
InetSocketAddress address = new InetSocketAddress(55555);
ss.bind(address);
ssc.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("端口注册完毕!");
while (true) {
selector.select();
Set selectionKeys = selector.selectedKeys();
Iterator iter = selectionKeys.iterator();
ByteBuffer echoBuffer = ByteBuffer.allocate(20);
SocketChannel sc;
while (iter.hasNext()) {
SelectionKey key =(SelectionKey) iter.next();
if ((key.readyOps() & SelectionKey.OP_ACCEPT) == SelectionKey.OP_ACCEPT) {
ServerSocketChannel subssc = (ServerSocketChannel) key
.channel();
sc = subssc.accept();
sc.configureBlocking(false);
sc.register(selector, SelectionKey.OP_READ);
iter.remove();
System.out.println("有新连接:" + sc);
} else if ((key.readyOps() & SelectionKey.OP_READ) == SelectionKey.OP_READ) {
sc = (SocketChannel) key.channel();
while (true) {
echoBuffer.clear();
int a;
try {
a = sc.read(echoBuffer);
} catch (Exception e) {
e.printStackTrace();
break;
}
if (a == -1)
break;
if (a > 0) {
byte[] b = echoBuffer.array();
System.out.println("接收数据: " + new String(b));
echoBuffer.flip();
sc.write(echoBuffer);
System.out.println("返回数据: " + new String(b));
}
}
sc.close();
System.out.println("连接结束");
System.out.println("=============================");
iter.remove();
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args){
server s = new server();
s.start();
}
}
首先进来acceptable,但是你又没注册其他的key,然后都remove了再哪来key进入,迭代数量应该为0了吧
你在key.isAcceptable()里面没有做任何操作,实际上就是你根本就没有建立连接
该channel一直处于就绪状态,即使remove掉把selectedKey里面删除了,keys里面还是存在
下次select发现状态还是就绪就继续选择出来
你应该在key.isAcceptable()里面accept,然后将返回的socketChannel置为可读key