1、步骤
（1）创建SocketChannel实例，并将其配置为非阻塞模式，只有在SocketChannel实例中，任何I/O操作都是非阻塞的。
（2）使用connect()方法连接服务器，同时使用while循环连续检测和完全连接。在需要立即进行I/O操作之前，必须使用finishConnect()来完成连接过程。
（3）用ByteBuffer读写字节，假如SelectableChannel是一种非阻塞模式，那么它的I/O操作读写字节可能比实际字节少，甚至没有。因此，我们使用循环连续的读写来确保读写完成。
2、实例
public class NonBlockingTCPClient {
public static void main(String[] args) {
byte[] data = "hello".getBytes();
SocketChannel channel = null;
try {
// 1. open a socket channel
channel = SocketChannel.open();
// adjust to be nonblocking
channel.configureBlocking(false);
// 2. init connection to server and repeatedly poll with complete
// connect() and finishConnect() are nonblocking operation, both return immediately
if (!channel.connect(new InetSocketAddress(InetAddress.getLocalHost(), 8899))) {
while (!channel.finishConnect()) {
System.out.print(".");
}
}
System.out.println("Connected to server...");
ByteBuffer writeBuffer = ByteBuffer.wrap(data);
ByteBuffer readBuffer = ByteBuffer.allocate(data.length);
int totalBytesReceived = 0;
int bytesReceived;
// 3. read and write bytes
while (totalBytesReceived < data.length) {
if (writeBuffer.hasRemaining()) {
channel.write(writeBuffer);
}
if ((bytesReceived = channel.read(readBuffer)) == -1) {
throw new SocketException("Connection closed prematurely");
}
totalBytesReceived += bytesReceived;
System.out.print(".");
}
System.out.println("Server said: " + new String(readBuffer.array()));
} catch (IOException e) {
e.printStackTrace();
} finally {
// 4 .close socket channel
try {
if (channel != null) {
channel.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
以上就是SocketChannel在java中实现客户端的方法，希望对大家有所帮助。更多Java学习指路：Java基础
本教程操作环境：windows7系统、java10版，DELL G3电脑。
