NIO、ServerSocketChannel常用方法、NIO方式实现客户端与服务端通信demo
ServerSocket是-BIO的网络编程通信方式
ServerSocketChannel-NIO（new io）是新的IO网络编程通信方式，他和BIO最大不同在于NIO是异步的方式，而BIO是同步的方式
ServerSocketChannel：用于面向流的侦听套接字可选通道
类树形图
ServerSocketChannel常用方法：
- SocketChannel accept()：接受此频道套接字的链接
- ServerSocketChannel bind(SocketAddress local, int backlog):将通道的套接字绑定到本地地址，并配置套接字以监听链接,backlog为套接字上挂起的连接的最大数量，如果backlog参数的值为0或负值，则使用实现特定的默认值（默认为0）
- SocketAddress getLocalAddress()：返回此通道套接字所丙丁的套接字地址
- static ServerSocketChannel open()：打开服务器通道
- ServerSocketChannel setOption(SocketOption name, T value)：设置套接字选项的值
- ServerSocket socket()：检索与此通道关联的服务器套接字
- int validOps()：返回此频道支持的操作的操作集，如SelectionKey.OP_ACCEPT
下面的方法是从 AbstractSelectableChannel
继承下来的常用的如下
- Object blockingLock():检索 configureBlocking 和 register 方法同步的对象
- SelecttableChannel configureBlocking(boolean block)调整此频道的阻塞模式（true：阻塞模式 false：非阻塞模式）
- void implCloseChannel()：关闭此频道 会调用下面的implCloseSelectableChannel，并且关闭密钥
- void implCloseSelectableChannel():关闭此选择的频道
- boolean isBlocking()：告诉这个通道上的每个I/O操作是否阻塞直到完成，如果结果为tue，则当前通道处于阻塞模式
- boolean isRegistered()：告知这个频道当前是否在任何选择器上注册
- SelectionKey keyFor（Selector sel）：检索表示频道注册的键与给定的选择器
- SelectorProvider provider()：返回创建此通道的提供程序
- SelectionKey register（Selector sel， int ops， Object att）：使用给定的选择器注册此频道，返回一个选择键，sel要注册的选择器、ops为所得密钥设置、att为密钥的附件，可能为null
下面为实例demo
服务器端Main方法
package com.zhr.nio;
public class TimeServer {
public static void main(String[] args) {
int port = 8080;
if(args != null && args.length > 0){
try {
port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) {
e.printStackTrace();
}
}
MultiplexerTimeServer timeServer = new MultiplexerTimeServer(port);
new Thread(timeServer, "NIO-MultiplexerTimeServer-001").start();
}
}
服务器处理过程
package com.zhr.nio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Set;
public class MultiplexerTimeServer implements Runnable {
private Selector selector;
private ServerSocketChannel servChannel;
private volatile boolean stop;
/**
* 初始化多路复用器，绑定监听端口
*/
public MultiplexerTimeServer(int port) {
try {
selector = Selector.open();
servChannel = ServerSocketChannel.open();
servChannel.configureBlocking(false);
servChannel.socket().bind(new InetSocketAddress(port), 1024);
servChannel.register(selector,
SelectionKey.OP_ACCEPT);
System.out.println("The time server is start in port :" + port);
} catch (IOException e) {
e.printStackTrace();
System.out.println(1);
}
}
public void stop() {
this.stop = true;
}
public void run() {
while (!stop) {
try {
selector.select(1000);
Set<SelectionKey> selectionKeys = selector.selectedKeys();
Iterator<SelectionKey> it = selectionKeys.iterator();
SelectionKey key = null;
while (it.hasNext()) {
key = it.next();
it.remove();
try {
handleInput(key);
} catch (Exception e) {
if (key != null) {
key.cancel();
if (key.channel() != null) {
key.channel().close();
}
}
e.printStackTrace();
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
if (selector != null) {
try {
selector.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void handleInput(SelectionKey key) throws IOException {
//密钥是否有效
if (key.isValid()) {
//这个密钥通道是否准备好接受新的套接字连接
if (key.isAcceptable()) {
ServerSocketChannel ssc = (ServerSocketChannel) key.channel();
SocketChannel sc = ssc.accept();
sc.configureBlocking(false);
sc.register(selector, SelectionKey.OP_READ);
}
if (key.isReadable()) {
SocketChannel sc = (SocketChannel) key.channel();
ByteBuffer readBuffer = ByteBuffer.allocate(1024);
int readBytes = sc.read(readBuffer);
if (readBytes > 0) {
readBuffer.flip();
byte[] bytes = new byte[readBuffer.remaining()];
readBuffer.get(bytes);
String body = new String(bytes, "UTF-8");
System.out.println("The time server receive order :" + body);
String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new java.util.Date(System.currentTimeMillis()).toString()
: "BAD ORDER";
doWrite(sc, currentTime);
} else if (readBytes < 0) {
key.channel();
sc.close();
} else {
;//读到0字节，忽略
}
}
}
}
private void doWrite(SocketChannel channel, String response) throws IOException {
if (response != null && response.trim().length() > 0) {
byte[] bytes = response.getBytes();
ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
writeBuffer.put(bytes);
writeBuffer.flip();
channel.write(writeBuffer);
}
}
}
客户端Main方法
package com.zhr.nio;
public class TimeClient {
public static void main(String[] args) {
int port = 8080;
if (args != null && args.length > 0) {
try {
port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) {
e.printStackTrace();
}
}
new Thread(new TimeClientHandle("127.0.0.1", port), "TimeClient-001")
.start();
}
}
客户端的处理器
package com.zhr.nio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;
public class TimeClientHandle implements Runnable {
private String host;
private int port;
private Selector selector;
private SocketChannel socketChannel;
private volatile boolean stop;
public TimeClientHandle(String host, int port) {
this.host = host == null ? "127.0.0.1" : host;
this.port = port;
try {
selector = Selector.open();
socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
}
public void run() {
try {
doConnect();
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
while (!stop) {
try {
selector.select(1000);
Set<SelectionKey> selectionKeys = selector.selectedKeys();
Iterator<SelectionKey> it = selectionKeys.iterator();
SelectionKey key = null;
while (it.hasNext()) {
key = it.next();
it.remove();
handleInput(key);
}
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
}
if (selector != null) {
try {
selector.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void handleInput(SelectionKey key) throws IOException {
if (key.isValid()) {
SocketChannel sc = (SocketChannel) key.channel();
if (key.isConnectable()) {
if (sc.finishConnect()) {
sc.register(selector, SelectionKey.OP_READ);
doWrite(sc);
} else {
System.exit(1);//连接失败，程序退出
}
}
if (key.isReadable()) {
ByteBuffer readBuffer = ByteBuffer.allocate(1024);
int readBytes = sc.read(readBuffer);
if (readBytes > 0) {
readBuffer.flip();
byte[] bytes = new byte[readBuffer.remaining()];
readBuffer.get(bytes);
String body = new String(bytes, "UTF-8");
System.out.println("Now is :" + body);
this.stop = true;
} else if (readBytes < 0) {
key.cancel();
sc.close();
} else {
;//读到0字节，忽略
}
}
}
}
private void doConnect() throws IOException {
if (socketChannel.connect(new InetSocketAddress(host, port))) {
socketChannel.register(selector, SelectionKey.OP_READ);
doWrite(socketChannel);
} else {
socketChannel.register(selector, SelectionKey.OP_CONNECT);
}
}
private void doWrite(SocketChannel sc) throws IOException {
byte[] req = "QUERY TIME ORDER".getBytes();
ByteBuffer writeBuffer = ByteBuffer.allocate(req.length);
writeBuffer.put(req);
writeBuffer.flip();
sc.write(writeBuffer);
if (!writeBuffer.hasRemaining()) {
System.out.println("Send order 2 server succeed.");
}
}
}