NIO使用的例子
作者：御风逍遥
链接：http://www.jianshu.com/p/a9d030fec081
package nio;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.*;
public class Server {
private Selector selector;
private ByteBuffer readBuffer = ByteBuffer.allocate(1024); //调整缓存的大小可以看到打印输出的变化
private ByteBuffer sendBuffer = ByteBuffer.allocate(1024); //调整缓存的大小可以看到打印输出的变化
String str;
public void start() throws IOException {
// 打开服务器套接字通道
ServerSocketChannel ssc = ServerSocketChannel.open();
// 服务器配置为非阻塞
ssc.configureBlocking(false);
// 进行服务的绑定
ssc.bind(new InetSocketAddress("localhost", 8001));
// 通过open()方法找到Selector
selector = Selector.open();
System.err.println(selector);
// 注册到selector，等待连接
ssc.register(selector, SelectionKey.OP_ACCEPT);
while (!Thread.currentThread().isInterrupted()) {
selector.select(); // 线程会在此处阻塞，执行处于阻塞模式的选择操作
Set keys = selector.selectedKeys();
Iterator keyIterator = keys.iterator();
while (keyIterator.hasNext()) {
SelectionKey key = keyIterator.next();
// 判断当前key是否可用，可用的条件是该key没有被取消掉，并且通道选择器都没有关闭
if (!key.isValid()) {
continue;
}
// 判断当前key中包含的通道知否准备好接受一个新的套接字连接
if (key.isAcceptable()) {
accept(key);
} else if (key.isReadable()) {
read(key);
} else if (key.isWritable()) {
write(key);
}
keyIterator.remove(); //该事件已经处理，可以丢弃
}
}
}
private void write(SelectionKey key) throws IOException, ClosedChannelException {
SocketChannel channel = (SocketChannel) key.channel();
System.out.println("有数据写入: " + str);
sendBuffer.clear();
sendBuffer.put(str.getBytes());
sendBuffer.flip();
channel.write(sendBuffer);
channel.register(selector, SelectionKey.OP_READ);
}
private void read(SelectionKey key) throws IOException {
SocketChannel socketChannel = (SocketChannel) key.channel();
// 清空buffer，为写入数据做准备
this.readBuffer.clear();
int numRead;
try {
numRead = socketChannel.read(this.readBuffer);
} catch (IOException e) {
// 远程强制关闭连接,取消选择键并关闭通道
key.cancel();
socketChannel.close();
return;
}
str = new String(readBuffer.array(), 0, numRead);
System.out.println("读取到内容： " + str);
socketChannel.register(selector, SelectionKey.OP_WRITE);
}
private void accept(SelectionKey key) throws IOException {
// 从key中获取通道的时候需要进行转型
ServerSocketChannel ssc = (ServerSocketChannel) key.channel();
// 接受通道中包含的连接
SocketChannel clientChannel = ssc.accept();
clientChannel.configureBlocking(false);
clientChannel.register(selector, SelectionKey.OP_READ);
System.out.println("有新的连接产生： " + clientChannel.getRemoteAddress());
}
public static void main(String[] args) throws IOException {
System.out.println("server started...");
new Server().start();
}
}
package 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.Scanner;
import java.util.Set;
public class Client {
ByteBuffer writeBuffer = ByteBuffer.allocate(1024);
ByteBuffer readBuffer = ByteBuffer.allocate(1024);
public void start() throws IOException {
// 打开socket通道
SocketChannel sc = SocketChannel.open();
// 设置为非阻塞
sc.configureBlocking(false);
// 连接服务器地址和端口
sc.connect(new InetSocketAddress("localhost", 8001));
// 打开选择器
Selector selector = Selector.open();
// 注册连接服务器socket的动作
sc.register(selector, SelectionKey.OP_CONNECT);
Scanner scanner = new Scanner(System.in);
while (true) {
// 选择一组键，其相应的通道已为 I/O 操作准备就绪
// 此方法执行处于阻塞模式的选择操作
selector.select();
// 返回此选择器的已选择键集
Set keys = selector.selectedKeys();
System.out.println("keys=" + keys.size());
Iterator keyIterator = keys.iterator();
while (keyIterator.hasNext()) {
SelectionKey key = keyIterator.next();
keyIterator.remove();
// 判断此通道上是否正在进行连接操作
if (key.isConnectable()) {
sc.finishConnect();
sc.register(selector, SelectionKey.OP_WRITE);
System.out.println("server connected...");
break;
} else if (key.isWritable()) { // 写数据
System.out.print("please input message:");
String message = scanner.nextLine();
// ByteBuffer writeBuffer =
// ByteBuffer.wrap(message.getBytes());
writeBuffer.clear();
writeBuffer.put(message.getBytes());
// 将缓冲区各标志复位,因为向里面put了数据标志被改变要想从中读取数据发向服务器,就要复位
writeBuffer.flip();
sc.write(writeBuffer);
// 注册写操作,每个chanel只能注册一个操作，最后注册的一个生效
// 如果你对不止一种事件感兴趣，那么可以用“位或”操作符将常量连接起来
// int interestSet = SelectionKey.OP_READ |
// SelectionKey.OP_WRITE;
// 使用interest集合
sc.register(selector, SelectionKey.OP_READ);
sc.register(selector, SelectionKey.OP_WRITE);
sc.register(selector, SelectionKey.OP_READ);
} else if (key.isReadable()) {// 读取数据
System.out.print("receive message:");
SocketChannel client = (SocketChannel) key.channel();
// 将缓冲区清空以备下次读取
readBuffer.clear();
int num = client.read(readBuffer);
System.out.println(new String(readBuffer.array(), 0, num));
// 注册读操作，下一次读取
sc.register(selector, SelectionKey.OP_WRITE);
}
}
}
}
public static void main(String[] args) throws IOException {
new Client().start();
}
}