NIO 网络编程应用实例-群聊系统
目标
需求:进一步理解 NIO 非阻塞网络编程机制，实现多人群聊
- 编写一个 NIO 群聊系统，实现客户端与客户端的通信需求（非阻塞）
- 服务器端：可以监测用户上线，离线，并实现消息转发功能
- 客户端：通过 channel 可以无阻塞发送消息给其它所有客户端用户，同时可以接受其它客户端用户通过服务端转发来的消息
服务端代码实现
/****
监听接收和读就绪事件
1.SelectionKey是接收事件:
直接获取当前接入的客户端通道
切换成非阻塞模式
将本客户端通道注册到选择器
监听读就绪事件
移除当前接收事件对应的SelectionKey
2.SelectionKey是读就绪事件:
获取消息
转发消息到其他所有的socket,排除自己
****/
public class Server {
//定义属性
private Selector selector;
private ServerSocketChannel ssChannel;
private static final int PORT = 9999;
//构造器
//初始化工作
public Server() {
try {
// 1、获取通道
ssChannel = ServerSocketChannel.open();
// 2、切换为非阻塞模式
ssChannel.configureBlocking(false);
// 3、绑定连接的端口
ssChannel.bind(new InetSocketAddress(PORT));
// 4、获取选择器Selector
selector = Selector.open();
// 5、将通道都注册到选择器上去，并且开始指定监听接收事件
ssChannel.register(selector , SelectionKey.OP_ACCEPT);
}catch (IOException e) {
e.printStackTrace();
}
}
//监听
public void listen() {
System.out.println("监听线程: " + Thread.currentThread().getName());
try {
while (selector.select() > 0){
System.out.println("开始一轮事件处理~~~");
// 7、获取选择器中的所有注册的通道中已经就绪好的事件
Iterator it = selector.selectedKeys().iterator();
// 8、开始遍历这些准备好的事件
while (it.hasNext()){
// 提取当前这个事件
SelectionKey sk = it.next();
// 9、判断这个事件具体是什么
if(sk.isAcceptable()){
// 10、直接获取当前接入的客户端通道
SocketChannel schannel = ssChannel.accept();
// 11 、切换成非阻塞模式
schannel.configureBlocking(false);
// 12、将本客户端通道注册到选择器
System.out.println(schannel.getRemoteAddress() + " 上线 ");
schannel.register(selector , SelectionKey.OP_READ);
//提示
}else if(sk.isReadable()){
//处理读 (专门写方法..)
readData(sk);
}
it.remove(); // 处理完毕之后需要移除当前事件
}
}
}catch (Exception e) {
e.printStackTrace();
}finally {
//发生异常处理....
}
}
//读取客户端消息
private void readData(SelectionKey key) {
//取到关联的channle
SocketChannel channel = null;
try {
//得到channel
channel = (SocketChannel) key.channel();
//创建buffer
ByteBuffer buffer = ByteBuffer.allocate(1024);
int count = channel.read(buffer);
//根据count的值做处理
if(count > 0) {
//把缓存区的数据转成字符串
String msg = new String(buffer.array());
//输出该消息
System.out.println("form 客户端: " + msg);
//向其它的客户端转发消息(去掉自己), 专门写一个方法来处理
sendInfoToOtherClients(msg, channel);
}
}catch (IOException e) {
try {
System.out.println(channel.getRemoteAddress() + " 离线了..");
e.printStackTrace();
//取消注册
key.cancel();
//关闭通道
channel.close();
}catch (IOException e2) {
e2.printStackTrace();;
}
}
}
//转发消息给其它客户(通道)
private void sendInfoToOtherClients(String msg, SocketChannel self ) throws IOException{
System.out.println("服务器转发消息中...");
System.out.println("服务器转发数据给客户端线程: " + Thread.currentThread().getName());
//遍历 所有注册到selector 上的 SocketChannel,并排除 self
for(SelectionKey key: selector.keys()) {
//通过 key 取出对应的 SocketChannel
Channel targetChannel = key.channel();
//排除自己
if(targetChannel instanceof SocketChannel && targetChannel != self) {
//转型
SocketChannel dest = (SocketChannel)targetChannel;
//将msg 存储到buffer
ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
//将buffer 的数据写入 通道
dest.write(buffer);
}
}
}
public static void main(String[] args) {
//创建服务器对象
Server groupChatServer = new Server();
groupChatServer.listen();
}
}
客户端代码实现
package com.itheima.chat;
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;
public class Client {
//定义相关的属性
private final String HOST = "127.0.0.1"; // 服务器的ip
private final int PORT = 9999; //服务器端口
private Selector selector;
private SocketChannel socketChannel;
private String username;
//构造器, 完成初始化工作
public Client() throws IOException {
selector = Selector.open();
//连接服务器
socketChannel = socketChannel.open(new InetSocketAddress("127.0.0.1", PORT));
//设置非阻塞
socketChannel.configureBlocking(false);
//将channel 注册到selector
socketChannel.register(selector, SelectionKey.OP_READ);
//得到username
username = socketChannel.getLocalAddress().toString().substring(1);
System.out.println(username + " is ok...");
}
//向服务器发送消息
public void sendInfo(String info) {
info = username + " 说：" + info;
try {
socketChannel.write(ByteBuffer.wrap(info.getBytes()));
}catch (IOException e) {
e.printStackTrace();
}
}
//读取从服务器端回复的消息
public void readInfo() {
try {
int readChannels = selector.select();
if(readChannels > 0) {//有可以用的通道
Iterator iterator = selector.selectedKeys().iterator();
while (iterator.hasNext()) {
SelectionKey key = iterator.next();
if(key.isReadable()) {
//得到相关的通道
SocketChannel sc = (SocketChannel) key.channel();
//得到一个Buffer
ByteBuffer buffer = ByteBuffer.allocate(1024);
//读取
sc.read(buffer);
//把读到的缓冲区的数据转成字符串
String msg = new String(buffer.array());
System.out.println(msg.trim());
}
}
iterator.remove(); //删除当前的selectionKey, 防止重复操作
} else {
//System.out.println("没有可以用的通道...");
}
}catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws Exception {
//启动我们客户端
Client chatClient = new Client();
//启动一个线程, 每个3秒，读取从服务器发送数据
new Thread() {
public void run() {
while (true) {
chatClient.readInfo();
try {
Thread.currentThread().sleep(3000);
}catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}.start();
//发送数据给服务器端
Scanner scanner = new Scanner(System.in);
while (scanner.hasNextLine()) {
String s = scanner.nextLine();
chatClient.sendInfo(s);
}
}
}
尚硅谷代码实现
package com.atguigu.nio.groupchat;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
public class GroupChatServer {
//定义属性
private Selector selector;
private ServerSocketChannel listenChannel;
private static final int PORT = 6667;
//构造器
//初始化工作
public GroupChatServer() {
try {
//得到选择器
selector = Selector.open();
//ServerSocketChannel
listenChannel = ServerSocketChannel.open();
//绑定端口
listenChannel.socket().bind(new InetSocketAddress(PORT));
//设置非阻塞模式
listenChannel.configureBlocking(false);
//将该listenChannel 注册到selector
listenChannel.register(selector, SelectionKey.OP_ACCEPT);
}catch (IOException e) {
e.printStackTrace();
}
}
//监听
public void listen() {
System.out.println("监听线程: " + Thread.currentThread().getName());
try {
//循环处理
while (true) {
int count = selector.select();//这2步可以放到while判断中
if(count > 0) {//如果有事件处理
//遍历得到selectionKey 集合
Iterator iterator = selector.selectedKeys().iterator();
while (iterator.hasNext()) {
//取出selectionkey
SelectionKey key = iterator.next();
//监听到accept
if(key.isAcceptable()) {
SocketChannel sc = listenChannel.accept();
sc.configureBlocking(false);
//将该 sc 注册到seletor,监听事件为读事件
sc.register(selector, SelectionKey.OP_READ);
//提示
System.out.println(sc.getRemoteAddress() + " 上线 ");
}
if(key.isReadable()) { //通道发送read事件，即通道是可读的状态
//处理读 (专门写方法..)
readData(key);
}
//当前的key 删除，防止重复处理
iterator.remove();
}
} else {
System.out.println("等待....");
}
}
}catch (Exception e) {
e.printStackTrace();
}finally {
//发生异常处理....
}
}
//读取客户端消息
private void readData(SelectionKey key) {
//取到关联的channle
SocketChannel channel = null;
try {
//得到channel
channel = (SocketChannel) key.channel();
//创建buffer
ByteBuffer buffer = ByteBuffer.allocate(1024);
int count = channel.read(buffer);
//根据count的值做处理
if(count > 0) {
//把缓存区的数据转成字符串
String msg = new String(buffer.array());
//输出该消息
System.out.println("form 客户端: " + msg);
//向其它的客户端转发消息(去掉自己), 专门写一个方法来处理
sendInfoToOtherClients(msg, channel);
}
}catch (IOException e) {
try {
System.out.println(channel.getRemoteAddress() + " 离线了..");
//取消注册
key.cancel();
//关闭通道
channel.close();
}catch (IOException e2) {
e2.printStackTrace();;
}
}
}
//转发消息给其它客户(通道)
private void sendInfoToOtherClients(String msg, SocketChannel self ) throws IOException{
System.out.println("服务器转发消息中...");
System.out.println("服务器转发数据给客户端线程: " + Thread.currentThread().getName());
//遍历 所有注册到selector 上的 SocketChannel,并排除 self
for(SelectionKey key: selector.keys()) {
//通过 key 取出对应的 SocketChannel
Channel targetChannel = key.channel();
//排除自己
if(targetChannel instanceof SocketChannel && targetChannel != self) {
//转型
SocketChannel dest = (SocketChannel)targetChannel;
//将msg 存储到buffer
ByteBuffer buffer = ByteBuffer.wrap(msg.getBytes());
//将buffer 的数据写入 通道
dest.write(buffer);
}
}
}
public static void main(String[] args) {
//创建服务器对象
GroupChatServer groupChatServer = new GroupChatServer();
groupChatServer.listen();
}
}
package com.atguigu.nio.groupchat;
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 GroupChatClient {
//定义相关的属性
private final String HOST = "127.0.0.1"; // 服务器的ip
private final int PORT = 6667; //服务器端口
private Selector selector;
private SocketChannel socketChannel;
private String username;
//构造器, 完成初始化工作
public GroupChatClient() throws IOException {
selector = Selector.open();
//连接服务器
socketChannel = socketChannel.open(new InetSocketAddress("127.0.0.1", PORT));
//设置非阻塞
socketChannel.configureBlocking(false);
//将channel 注册到selector
socketChannel.register(selector, SelectionKey.OP_READ);
//得到username
username = socketChannel.getLocalAddress().toString().substring(1);
System.out.println(username + " is ok...");
}
//向服务器发送消息
public void sendInfo(String info) {
info = username + " 说：" + info;
try {
socketChannel.write(ByteBuffer.wrap(info.getBytes()));
}catch (IOException e) {
e.printStackTrace();
}
}
//读取从服务器端回复的消息
public void readInfo() {
try {
int readChannels = selector.select();
if(readChannels > 0) {//有可以用的通道
Iterator iterator = selector.selectedKeys().iterator();
while (iterator.hasNext()) {
SelectionKey key = iterator.next();
if(key.isReadable()) {
//得到相关的通道
SocketChannel sc = (SocketChannel) key.channel();
//得到一个Buffer
ByteBuffer buffer = ByteBuffer.allocate(1024);
//读取
sc.read(buffer);
//把读到的缓冲区的数据转成字符串
String msg = new String(buffer.array());
System.out.println(msg.trim());
}
}
iterator.remove(); //删除当前的selectionKey, 防止重复操作
} else {
//System.out.println("没有可以用的通道...");
}
}catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws Exception {
//启动我们客户端
GroupChatClient chatClient = new GroupChatClient();
//启动一个线程, 每个3秒，读取从服务器发送数据
new Thread() {
public void run() {
while (true) {
chatClient.readInfo();
try {
Thread.currentThread().sleep(3000);
}catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}.start();
//发送数据给服务器端
Scanner scanner = new Scanner(System.in);
while (scanner.hasNextLine()) {
String s = scanner.nextLine();
chatClient.sendInfo(s);
}
}
}
