收藏 java nio 问题
0
悬赏园豆：80
[已解决问题]
解决于 2014-03-28 15:36
问题描述如下：
鄙人在写nio简单例子的时候出现了很奇怪的问题，服务器端部分代码如下：
while (selector.select() > 0) { Set<SelectionKey> readyKeys = selector.selectedKeys(); Iterator it = readyKeys.iterator(); System.out.println("while out"); while (it.hasNext()) { System.out.println("while in"); SelectionKey key = (SelectionKey) it.next(); it.remove(); if (key.isAcceptable()) { System.out.println("Key is Acceptable"); socket = (SocketChannel) ssc.accept(); socket.configureBlocking(false); socket.register(selector,SelectionKey.OP_READ|SelectionKey.OP_WRITE); } if (key.isReadable()) { System.out.println("Key is readable"); socket = (SocketChannel) key.channel(); ByteBuffer buf = ByteBuffer.allocate(25); buf.clear(); socket.read(buf); buf.flip(); Charset charset = Charset.forName("us-ascii"); CharsetDecoder decoder = charset.newDecoder(); CharBuffer charBuffer = decoder.decode(buf); String result = charBuffer.toString(); System.out.println("Receive Data:" + result); // key.cancel();如果这个注释的话，就会进行无限循环 } }
客户端发送代码：为
public static int sendMessage(SocketChannel client) { String msg = null; ByteBuffer bytebuf=ByteBuffer.allocate(1024); int nBytes = 0; try { msg = "It's message from client!"; System.out.println("msg is "+msg); bytebuf.clear(); bytebuf.put(msg.getBytes()); bytebuf.flip(); nBytes = client.write(bytebuf); System.out.println("It's message from client!".getBytes().length); client.close(); } catch (IOException e) { e.printStackTrace(); } return nBytes; }
客户端和服务器端的部分代码就是上面的，客户端发送数据给服务器端，服务器按道理执行了
SelectionKey key = (SelectionKey) it.next();
it.remove();的代码之后注销了该键，如果执行完读操作之后，只要加上key.cancel()之后才可以正常读取一条数据。it.remove()之后为什么selector.select() > 0依然成立，运行代码的打印结果：
while out
while in
Key is readable
Receive Data:
while out
while in
Key is readable
Receive Data:
while out
while in
Key is readable
Receive Data:。。。。。
求高手解答。
最佳答案
1
while (selector.select() > 0)
没有cancel这个key的话，select（）返回一直都是大于0的数
收获园豆：80
现在我想想也是，毕竟cancel之后，才会把key从集合中移除，但是我保持长连接的话，cancel之后会把连接也中断吗？
