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下面的服务器运行起来，当客户端多个请求过来的时候一直陷入死循环，selector.select();一直有值，不知道哪里出了问题，求大佬解释一下。
package com.wangjun.io.nio;
public class TimeServer {
public static void main(String[] args) {
int port = 8080;
MultiplexerTimeServer timeServer = new MultiplexerTimeServer(port);
new Thread(timeServer, "NIO_MultiplexerTimeServer-001").start();
}
}package com.wangjun.io.nio;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
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.Date;
import java.util.Iterator;
import java.util.Set;
public class MultiplexerTimeServer implements Runnable {
private Selector selector;
private ServerSocketChannel servChannel;
private volatile boolean stop;
private final long SLEEP_TIME = 10000L;
/**
* 初始化多路复用器，绑定监听端口
*
* @param port
*/
public MultiplexerTimeServer(int port) {
try {
selector = Selector.open();
servChannel = ServerSocketChannel.open();
servChannel.configureBlocking(false);
servChannel.socket().bind(new InetSocketAddress(port), 1024);//???1024这个参数什么作用
servChannel.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("The nio time server start in port:" + port);
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
}
public void stop() {
this.stop = true;
}
@Override
public void run() {
while (!stop) {
try {
selector.select();
Set<SelectionKey> selectedKeys = selector.selectedKeys();
Iterator<SelectionKey> it = selectedKeys.iterator();
SelectionKey key = null;
System.out.println("key size=" + selectedKeys.size());
while (it.hasNext()) {
System.out.println("it has next");
key = it.next();
it.remove();
try {
new Thread(new MyThread(key)).start();
} catch (Exception e) {
e.printStackTrace();
if (key != null) {
key.cancel();
if (key.channel() != null) {
key.channel().close();
}
}
}
}
} catch (Throwable t) {
t.printStackTrace();
}
}
//多路复用器关闭后，所有注册在上面的Channel和Pipe等资源都会被自动去注册并关闭，所有不需要重复释放资源
if (selector != null) {
try {
selector.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
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);
}
}
class MyThread implements Runnable {
private SelectionKey key;
public MyThread(SelectionKey key) {
this.key = key;
}
@Override
public void run() {
long startTime = System.currentTimeMillis();
try {
if (key.isValid()) {
// 处理新接入的请求消息
if (key.isAcceptable()) {
System.out.println("收到 accept 请求");
ServerSocketChannel ssc = (ServerSocketChannel) key.channel();
SocketChannel sc = ssc.accept();
sc.configureBlocking(false);
sc.register(selector, SelectionKey.OP_READ);
}
if (key.isReadable()) {
System.out.println("收到 read 请求，休眠" + SLEEP_TIME/1000 + "s");
try {
Thread.sleep(SLEEP_TIME);
} catch (InterruptedException e) {
e.printStackTrace();
}
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("时间服务器收到的命令是:" + body);
String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body)
? new Date(System.currentTimeMillis()).toString()
: "BAD ORDER";
doWrite(sc, currentTime);
} else if (readBytes < 0) {
System.out.println("对端链路关闭");
// 对端链路关闭
key.cancel();
sc.close();
} else {
System.out.println("收到0字节");
// 读到0字节，忽略
}
}
}else {
System.out.println("key is not valid");
}
} catch (ClosedChannelException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
System.out.println("执行线程耗费：" + (System.currentTimeMillis() - startTime)/1000 + "s");
}
}
}
}客户端：
package com.wangjun.io.nio;
public class TimeClient {
public static void main(String[] args) throws InterruptedException {
int port = 8080;
long start = System.currentTimeMillis();
Thread t1 = new Thread(new TimeClientHandle("127.0.0.1", port), "TimeClient-001");
Thread t2 = new Thread(new TimeClientHandle("127.0.0.1", port), "TimeClient-002");
t1.start();
t2.start();
t1.join();
t2.join();
System.out.println("执行2个线程耗费：" + (System.currentTimeMillis() - start));
}
}package com.wangjun.io.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;
this.port = port;
try {
selector = Selector.open();
socketChannel = SocketChannel.open();
socketChannel.configureBlocking(false);
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
}
@Override
public void run() {
try {
doConnect();
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
while(!stop) {
try {
selector.select();
Set<SelectionKey> selectedKeys = selector.selectedKeys();
Iterator<SelectionKey> it = selectedKeys.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();
}
}
}
}
} catch (Throwable t) {
t.printStackTrace();
}
}
//多路复用器关闭后，所有注册在上面的Channel和Pipe等资源都会被自动去注册并关闭，所有不需要重复释放资源
if (selector != null) {
try {
selector.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void handleInput(SelectionKey key) throws IOException {
if (key.isValid()) {
// 判断连接是否成功
SocketChannel sc = (SocketChannel) key.channel();
if(key.isConnectable()) {
if(sc.finishConnect()) {
sc.register(selector, SelectionKey.OP_READ);
doWrite(sc);
}else {
System.exit(1);
}
}
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("现在的时间是:" + body);
this.stop = true;
} else if (readBytes < 0) {
// 对端链路关闭
key.cancel();
sc.close();
} else {
// 读到0字节，忽略
}
}
}
}
private void doConnect() throws IOException {
//如果直连成功，则注册到多路复用器上，发送请求消息，读应答
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 to server succeed!");
}
}
}服务端和客户端都起来后，服务端的打印输出：
......
it has next
收到 read 请求，休眠10s
收到 read 请求，休眠10s
it has next
收到 read 请求，休眠10s
key size=2
it has next
it has next
收到 read 请求，休眠10s
收到 read 请求，休眠10s
key size=2
it has next
......一直在打开线程，不断循环，不知道是哪里处理问题，在服务端命名已经remove掉了key。
java
你的key没有cancel，而且如果有异常，
new Thread(new MyThread(key)).start();这行代码下面的异常也不会被捕获，导致调用不到cancel