tcp连接后java代码模拟控制台输入

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云端小梦 2025-01-07 10:01:10

文章标签 tcp连接后java代码模拟控制台输入 java nio.2群发 java System 服务器端 文章分类 Java 后端开发

以前都是用一般的socket编程，用线程来控制。最近突然用nio来做些东西。

nio的好处我来说一下：第一，读写都是基于块的，效率高。第二，通过引入selector,简化了网络编程模型，异步非阻塞。

既然有这么多好处，那就写个NIO TCP网络聊天室来练练手吧。

因为没有写gui，是基于控制台的所以没写私了的部分，只写了公共聊天室。(其实，既然是服务器端可以分发给所有人，分发给特定人也是很容易实现的。

注意：这里只是为了练手，联系服务器端分发消息到各个客户端。TCP 来写聊天室，在现实中是不可取的。IM都是基于UDP来写的。

先上代码吧。

服务器端代码 MySocketServer.java
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package com.kevin.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.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* @author kevin
*/
public class MySocketServer implements Runnable{
private boolean running;
private Selector selector;
String writeMsg;
StringBuffer sb=new StringBuffer();
SelectionKey ssckey;
public MySocketServer(){
running=true;
}
public void init(){
try {
selector = Selector.open();
ServerSocketChannel ssc = ServerSocketChannel.open();
ssc.configureBlocking(false);
ssc.socket().bind(new InetSocketAddress(2345));
ssckey=ssc.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("server is starting..."+new Date());
} catch (IOException ex) {
Logger.getLogger(MySocketServer.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static void main(String[] args){
MySocketServer server=new MySocketServer();
new Thread(server).start();
}
public void execute(){
try {
while(running){
int num=selector.select();
if(num>0){
Iterator it=selector.selectedKeys().iterator();
while(it.hasNext()){
SelectionKey key=it.next();
it.remove();
if(!key.isValid()) continue;
if(key.isAcceptable()){
System.out.println("isAcceptable");
getConn(key);
}
else if(key.isReadable()){
System.out.println("isReadable");
readMsg(key);
}
else if(key.isValid()&&key.isWritable()){
if(writeMsg!=null){
System.out.println("isWritable");
writeMsg(key);
}
}
else break;
}
}
Thread.yield();
}
} catch (IOException ex) {
Logger.getLogger(MySocketServer.class.getName()).log(Level.SEVERE, null, ex);
}
}
private void getConn(SelectionKey key) throws IOException {
ServerSocketChannel ssc=(ServerSocketChannel)key.channel();
SocketChannel sc=ssc.accept();
sc.configureBlocking(false);
sc.register(selector, SelectionKey.OP_READ);
System.out.println("build connection :"+sc.socket().getRemoteSocketAddress());
}
private void readMsg(SelectionKey key) throws IOException {
sb.delete(0, sb.length());
SocketChannel sc=(SocketChannel)key.channel();
System.out.print(sc.socket().getRemoteSocketAddress()+" ");
ByteBuffer buffer=ByteBuffer.allocate(1024);
buffer.clear();
int len=0;
StringBuffer sb=new StringBuffer();
while((len=sc.read(buffer))>0){
buffer.flip();
sb.append(new String(buffer.array(),0,len));
}
if(sb.length()>0) System.out.println("get from client:"+sb.toString());
if(sb.toString().trim().toLowerCase().equals("quit")){
sc.write(ByteBuffer.wrap("BYE".getBytes()));
System.out.println("client is closed "+sc.socket().getRemoteSocketAddress());
key.cancel();
sc.close();
sc.socket().close();
}
else{
String toMsg=sc.socket().getRemoteSocketAddress()+ "said:"+sb.toString();
System.out.println(toMsg);
writeMsg=toMsg;
/*
Iterator it=key.selector().keys().iterator();
while(it.hasNext()){
SelectionKey skey=it.next();
if(skey!=key&&skey!=ssckey){
SocketChannel client=(SocketChannel) skey.channel();
client.write(ByteBuffer.wrap(toMsg.getBytes()));
}
}
*
*/
/*
key.attach(toMsg);
key.interestOps(key.interestOps()|SelectionKey.OP_WRITE);
*
*/
Iterator it=key.selector().keys().iterator();
while(it.hasNext()){
SelectionKey skey=it.next();
if(skey!=key&&skey!=ssckey){
if(skey.attachment()!=null){
String str=(String) skey.attachment();
skey.attach(str+toMsg);
}else{
skey.attach(toMsg);
}
skey.interestOps(skey.interestOps()|SelectionKey.OP_WRITE);
}
}
selector.wakeup();//可有可无
}
}
public void run() {
init();
execute();
}
private void writeMsg(SelectionKey key) throws IOException {
System.out.println("++++enter write+++");
SocketChannel sc=(SocketChannel) key.channel();
String str=(String) key.attachment();
sc.write(ByteBuffer.wrap(str.getBytes()));
key.interestOps(SelectionKey.OP_READ);
}
}
客户端：MySocketClient.java
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package com.kevin.nio;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.Currency.*;
/**
*
* @author kevin
*/
public class MySocketClient implements Runnable{
Selector selector;
boolean running;
SocketChannel sc;
public MySocketClient(){
running=true;
}
public void init() {
try {
sc = SocketChannel.open();
sc.configureBlocking(false);
sc.connect(new InetSocketAddress("localhost", 2345));
} catch (IOException ex) {
Logger.getLogger(MySocketClient.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static void main(String[] args){
MySocketClient client=new MySocketClient();
new Thread(client).start();
}
public void execute(){
int num=0;
try {
while (!sc.finishConnect()) {
}
} catch (IOException ex) {
Logger.getLogger(MySocketClient.class.getName()).log(Level.SEVERE, null, ex);
}
ReadKeyBoard rkb=new ReadKeyBoard();
new Thread(rkb).start();
while(running){
try {
ByteBuffer buffer=ByteBuffer.allocate(1024);
buffer.clear();
StringBuffer sb=new StringBuffer();
Thread.sleep(500);
while((num=sc.read(buffer))>0){
sb.append(new String(buffer.array(),0,num));
buffer.clear();
}
if(sb.length()>0) System.out.println(sb.toString());
if(sb.toString().toLowerCase().trim().equals("bye")){
System.out.println("closed....");
sc.close();
sc.socket().close();
rkb.close();
running=false;
}
} catch (InterruptedException ex) {
Logger.getLogger(MySocketClient.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(MySocketClient.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
public void run() {
init();
execute();
}
class ReadKeyBoard implements Runnable{
boolean running2=true;
public ReadKeyBoard(){
}
public void close(){
running2=false;
}
public void run() {
BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
while(running2){
try {
System.out.println("enter some commands:");
String str = reader.readLine();
sc.write(ByteBuffer.wrap(str.getBytes()));
} catch (IOException ex) {
Logger.getLogger(ReadKeyBoard.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}
}

总结：

1. 服务器端一定注意注册需要的操作，不要注册不需要的操作。比如在连接被接受后，其实scoket是可以读和可以写的。这里的注册读的话，那么意味着，只有真的有数据来了，才会接到消息。但是随时可以写，如果这个时候注册读写的话(sc.register(selector, SelectionKey.OP_READ|SelectionKey.OP_WRITE);)，那么服务器就会进入cpu 100%的状态。所以当连接刚被接受的时候，一定要注册读sc.register(selector, SelectionKey.OP_READ);

2. 服务器端写有两种方法：一种就是直接写。第二种是加入ATTACH，然后，通过skey.interestOps(skey.interestOps()|SelectionKey.OP_WRITE);把写消息写到interestOps集合中。就出发了可写的通知了。注意第二种方式，在接到可写的通知后，处理完了消息后，还是得恢复只对写有兴趣的interestOps 如key.interestOps(SelectionKey.OP_READ);

3. 得到所有服务器端的连接的方式是key.selector().keys()，但是一定记得，里面有一个是SocketServerChannel注册的key，这个只可以接受连接，其他的什么都做不了。更不能写数据给客户端。所以一定记得剔除这个。不然程序会抛异常。

4. 客户端比较简单，所以可以用select的方式，也可以不用。

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