程序是通了，但是没法转发，获取不到对方ip。nio中 udp使用的是DatagramChannel ，但是SelectorKey.channel()转化之后的DatagramChannel，调用getRemoteAddress()获取不到对方的ip信息。
看了下java doc
这个意思差不多就是DatagramChannel 是面向数据报的，是无连接的，所以不需要知道对面ip。然后就为null了。
但是
在bio中，通过DatagramPacket 是可以获取到对方ip信息的。 所以 ip信息应该是在报文里了。所以我要怎么样才能从报文中拿到这个ip呢？
假如使用nio，默认必须要通过ByteBuf 去读取，这样子就获取不到完整的报文信息了。我服了！
以下是代码
public class Server {
private static LinkedList<SocketAddress> list=new LinkedList<SocketAddress>();
private static final ExecutorService executorService = Executors.newFixedThreadPool(4);
private static DatagramChannel server=null;
private static Selector selector=null;
static {
try{
server=DatagramChannel.open().bind(new InetSocketAddress(8889));
server.configureBlocking(false);
selector=Selector.open();
}catch (Exception e){
e.printStackTrace();
}
}
public static void main(String[] args)throws Exception {
server.register(selector, SelectionKey.OP_READ);
while (true){
if (selector.select()>0){
Set<SelectionKey> keys = selector.selectedKeys();
Iterator<SelectionKey> iterator = keys.iterator();
while (iterator.hasNext()){
SelectionKey selectionKey = iterator.next();
if (selectionKey.isReadable()){
saveIP(selectionKey);
String msg = readMsg(selectionKey);
broadcast(msg);
}
iterator.remove();
}}
}
}
public static void saveIP(SelectionKey selectionKey)throws Exception{
if (selectionKey.channel() instanceof DatagramChannel){
System.out.println(true);
}
DatagramChannel channel=(DatagramChannel)selectionKey.channel();
SocketAddress address = channel.getRemoteAddress();
if (!list.contains(address)){
list.add(address);
System.out.println("新增ip："+address);
}
System.out.println("当前udp 保存的ip数量："+list.size());
}
public static void broadcast(String msg) throws Exception{
ByteBuffer byteBuffer=ByteBuffer.wrap(msg.getBytes());
//DatagramPacket packet=new DatagramPacket(msg.getBytes(),0,msg.getBytes().length);
for (SocketAddress address:list
) {
executorService.submit(new Runnable() {
@Override
public void run() {
try{
server.send(byteBuffer,address);
}catch (Exception e){
System.out.println(Thread.currentThread().getName()+":"+address+"发送失败");
}
}
});
}
}
public static String readMsg(SelectionKey selectionKey)throws Exception{
DatagramChannel channel=(DatagramChannel)selectionKey.channel();
ByteBuffer byteBuffer=ByteBuffer.allocate(1024);
channel.receive(byteBuffer);
byteBuffer.flip();
String msg=new String(byteBuffer.array(),"utf-8");
System.out.println("收到消息："+msg);
return msg;
}
}