NIO Socket编程实例

1.阻塞模式实例　　

package IO;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.LinkedList;

class Target { // 表示一项任务
InetSocketAddress address;
SocketChannel channel;
Exception failure;
long connectStart; // 开始连接时的时间
long connectFinish = 0; // 连接成功时的时间
boolean shown = false; // 该任务是否已经打印

Target(String host) {
try {
address = new InetSocketAddress(InetAddress.getByName(host), 80);
} catch (IOException x) {
failure = x;
}
}

void show() { // 打印任务执行的结果
String result;
if (connectFinish != 0)
result = Long.toString(connectFinish - connectStart) + "ms";
else if (failure != null)
result = failure.toString();
else
result = "Timed out";
System.out.println(address + " : " + result);
shown = true;
}
}

public class PingClient {
private Selector selector;
// 存放用户新提交的任务
private LinkedList targets = new LinkedList();
// 存放已经完成的需要打印的任务
private LinkedList finishedTargets = new LinkedList();

public PingClient() throws IOException {
selector = Selector.open();
Connector connector = new Connector();
Printer printer = new Printer();
connector.start();
printer.start();
receiveTarget();
}

public static void main(String args[]) throws IOException {
new PingClient();
}

public void addTarget(Target target) {
// 向targets队列中加入一个任务
SocketChannel socketChannel = null;
try {
socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
socketChannel.connect(target.address);

target.channel = socketChannel;
target.connectStart = System.currentTimeMillis();

synchronized (targets) {
targets.add(target);
}
selector.wakeup();
} catch (Exception x) {
if (socketChannel != null) {
try {
socketChannel.close();
} catch (IOException xx) {
}
}
target.failure = x;
addFinishedTarget(target);
}
}

public void addFinishedTarget(Target target) {
// 向finishedTargets队列中加入一个任务
synchronized (finishedTargets) {
finishedTargets.notify();
finishedTargets.add(target);
}
}

public void printFinishedTargets() {
// 打印finisedTargets队列中的任务
try {
for (;;) {
Target target = null;
synchronized (finishedTargets) {
while (finishedTargets.size() == 0)
finishedTargets.wait();
target = (Target) finishedTargets.removeFirst();
}
target.show();
}
} catch (InterruptedException x) {
return;
}
}

public void registerTargets() {
// 取出targets队列中的任务，向Selector注册连接就绪事件
synchronized (targets) {
while (targets.size() > 0) {
Target target = (Target) targets.removeFirst();

try {
target.channel.register(selector, SelectionKey.OP_CONNECT,
target);
} catch (IOException x) {
try {
target.channel.close();
} catch (IOException e) {
e.printStackTrace();
}
target.failure = x;
addFinishedTarget(target);
}
}
}
}

public void processSelectedKeys() throws IOException {
// 处理连接就绪事件
for (Iterator it = selector.selectedKeys().iterator(); it.hasNext();) {
SelectionKey selectionKey = (SelectionKey) it.next();
it.remove();

Target target = (Target) selectionKey.attachment();
SocketChannel socketChannel = (SocketChannel) selectionKey
.channel();

try {
if (socketChannel.finishConnect()) {
selectionKey.cancel();
target.connectFinish = System.currentTimeMillis();
socketChannel.close();
addFinishedTarget(target);
}
} catch (IOException x) {
socketChannel.close();
target.failure = x;
addFinishedTarget(target);
}
}
}

//接收用户输入的地址，向targets队列中加入任务
public void receiveTarget() {
try {
BufferedReader localReader = new BufferedReader(
new InputStreamReader(System.in));
String msg = null;
while ((msg = localReader.readLine()) != null) {
if (!msg.equals("bye")) {
Target target = new Target(msg);
addTarget(target);
} else {
shutdown = true;
selector.wakeup();
break;
}
}
} catch (IOException e) {
e.printStackTrace();
}
}

boolean shutdown = false;

public class Printer extends Thread {
public Printer() {
setDaemon(true);
}

public void run() {
printFinishedTargets();
}
}

public class Connector extends Thread {
public void run() {
while (!shutdown) {
try {
registerTargets();
if (selector.select() > 0) {
processSelectedKeys();
}
} catch (Exception e) {
e.printStackTrace();
}
}
try {
selector.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}