Question

我看到另一个答案说read()将在对等方关闭时返回-1，而write()将抛出IOException。

尽管我的程序让我感到困惑：

ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.bind(new InetSocketAddress(0));

SocketChannel socket = SocketChannel.open(serverSocketChannel.getLocalAddress());
SocketChannel peer = serverSocketChannel.accept();

peer.close();

int read;
int write;

read = socket.read(ByteBuffer.allocate(1));
System.out.println("read = " + read);
write = socket.write(ByteBuffer.allocate(1));
System.out.println("write = " + write);

它输出：

read = -1
write = 1

read()方法返回-1，但是write()不会引发异常。

然后我尝试更改write()和read()的顺序：

write = socket.write(ByteBuffer.allocate(1));
System.out.println("write = " + write);
read = socket.read(ByteBuffer.allocate(1));
System.out.println("read = " + read);

输出：

write = 1
Exception in thread "main" java.io.IOException: An established connection was aborted by the software in your host machine
    at sun.nio.ch.SocketDispatcher.read0(Native Method)
    at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:43)
    at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
    at sun.nio.ch.IOUtil.read(IOUtil.java:197)
    at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:380)
    at Core.main(Core.java:76)

这让我更加困惑：write()仍然没有抛出IOException，但是有read()抛出。

我删除了write()，然后再添加一个read()：

write = socket.write(ByteBuffer.allocate(1));
System.out.println("write = " + write);
write = socket.write(ByteBuffer.allocate(1));
System.out.println("write = " + write);

输出看起来更奇怪：

write = 1
Exception in thread "main" java.io.IOException: An established connection 
was aborted by the software in your host machine
    at sun.nio.ch.SocketDispatcher.write0(Native Method)
    at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:51)
    at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:93)
    at sun.nio.ch.IOUtil.write(IOUtil.java:65)
    at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:471)
    at Core.main(Core.java:76)

第一个write()不会引发任何异常，但是第二个会引发任何异常。

我不知道结果是否未定义，因为我找不到关于文档中同级物的任何信息。预先感谢！

java-如何知道SocketChannel的另一端是否关闭？

0 个答案: