聊天室案例
用户登录后实现单聊和群聊功能。
1. 定义消息
按照业务功能的不同：分为登录消息，退出消息，单聊请求消息，单聊回复消息，建群消息，发群消息，回应群消息，进群消息和退群消息，心跳消息：
java
public class LoginRequestMessage extends Message {
private String username;
private String password;
public LoginRequestMessage() {
}
public LoginRequestMessage(String username, String password) {
this.username = username;
this.password = password;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public int getMessageType() {
return LoginRequestMessage;
}
}
java
public class LoginResponseMessage extends AbstractResponseMessage {
public LoginResponseMessage(boolean success, String reason) {
super(success, reason);
}
@Override
public int getMessageType() {
return LoginResponseMessage;
}
}
java
public class ChatRequestMessage extends Message {
private String content;
private String to;
private String from;
public ChatRequestMessage() {
}
public ChatRequestMessage(String from, String to, String content) {
this.from = from;
this.to = to;
this.content = content;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public String getTo() {
return to;
}
public void setTo(String to) {
this.to = to;
}
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
@Override
public int getMessageType() {
return ChatRequestMessage;
}
}
java
public class ChatResponseMessage extends AbstractResponseMessage {
private String from;
private String content;
public ChatResponseMessage(boolean success, String reason) {
super(success, reason);
}
public ChatResponseMessage(String from, String content) {
this.from = from;
this.content = content;
}
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
@Override
public int getMessageType() {
return ChatResponseMessage;
}
}
java
public class GroupCreateRequestMessage extends Message {
private String groupName;
private Set<String> members;
public GroupCreateRequestMessage(String groupName, Set<String> members) {
this.groupName = groupName;
this.members = members;
}
public String getGroupName() {
return groupName;
}
public void setGroupName(String groupName) {
this.groupName = groupName;
}
public Set<String> getMembers() {
return members;
}
public void setMembers(Set<String> members) {
this.members = members;
}
@Override
public int getMessageType() {
return GroupCreateRequestMessage;
}
}
java
public class GroupCreateResponseMessage extends AbstractResponseMessage {
public GroupCreateResponseMessage(boolean success, String reason) {
super(success, reason);
}
@Override
public int getMessageType() {
return GroupCreateResponseMessage;
}
}
java
public class GroupChatRequestMessage extends Message {
private String content;
private String groupName;
private String from;
public GroupChatRequestMessage(String from, String groupName, String content) {
this.content = content;
this.groupName = groupName;
this.from = from;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public String getGroupName() {
return groupName;
}
public void setGroupName(String groupName) {
this.groupName = groupName;
}
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
@Override
public int getMessageType() {
return GroupChatRequestMessage;
}
}
java
public class GroupChatResponseMessage extends AbstractResponseMessage {
private String from;
private String content;
public GroupChatResponseMessage(boolean success, String reason) {
super(success, reason);
}
public GroupChatResponseMessage(String from, String content) {
this.from = from;
this.content = content;
}
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
@Override
public int getMessageType() {
return GroupChatResponseMessage;
}
}
java
public class GroupJoinRequestMessage extends Message {
private String groupName;
private String username;
public GroupJoinRequestMessage(String username, String groupName) {
this.groupName = groupName;
this.username = username;
}
@Override
public int getMessageType() {
return GroupJoinRequestMessage;
}
public String getGroupName() {
return groupName;
}
public void setGroupName(String groupName) {
this.groupName = groupName;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
}
java
public class GroupJoinResponseMessage extends AbstractResponseMessage {
public GroupJoinResponseMessage(boolean success, String reason) {
super(success, reason);
}
@Override
public int getMessageType() {
return GroupJoinResponseMessage;
}
}
java
public class GroupQuitRequestMessage extends Message {
private String groupName;
private String username;
public GroupQuitRequestMessage(String username, String groupName) {
this.groupName = groupName;
this.username = username;
}
public String getGroupName() {
return groupName;
}
public void setGroupName(String groupName) {
this.groupName = groupName;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
@Override
public int getMessageType() {
return GroupQuitRequestMessage;
}
}
java
public class GroupQuitResponseMessage extends AbstractResponseMessage {
public GroupQuitResponseMessage(boolean success, String reason) {
super(success, reason);
}
@Override
public int getMessageType() {
return GroupQuitResponseMessage;
}
}
java
public class PingMessage extends Message {
@Override
public int getMessageType() {
return PingMessage;
}
}
2. 客户端代码
java
public static void main(String[] args) {
NioEventLoopGroup group = new NioEventLoopGroup();
LoggingHandler LOGGING_HANDLER = new LoggingHandler(LogLevel.DEBUG);
WXMessageCodec MESSAGE_CODEC = new WXMessageCodec();
CountDownLatch WAIT_FOR_LOGIN = new CountDownLatch(1);
AtomicBoolean LOGIN = new AtomicBoolean(false);
AtomicBoolean EXIT = new AtomicBoolean(false);
Scanner scanner = new Scanner(System.in);
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.channel(NioSocketChannel.class);
bootstrap.group(group);
bootstrap.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new LengthFieldBasedFrameDecoder(1024, 12, 4, 0, 0));
ch.pipeline().addLast(MESSAGE_CODEC);
// 用来判断是不是 读空闲时间过长，或 写空闲时间过长
// 3s 内如果没有向服务器写数据，会触发一个 IdleState#WRITER_IDLE 事件
ch.pipeline().addLast(new IdleStateHandler(0, 3, 0));
// ChannelDuplexHandler 可以同时作为入站和出站处理器
ch.pipeline().addLast(new ChannelDuplexHandler() {
// 用来触发特殊事件
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
IdleStateEvent event = (IdleStateEvent) evt;
// 触发了写空闲事件
if (event.state() == IdleState.WRITER_IDLE) {
log.debug("3s 没有写数据了，发送一个心跳包");
ctx.writeAndFlush(new PingMessage());
}
}
});
ch.pipeline().addLast("client handler", new ChannelInboundHandlerAdapter() {
// 接收响应消息
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
log.debug("msg: {}", msg);
if ((msg instanceof LoginResponseMessage)) {
LoginResponseMessage response = (LoginResponseMessage) msg;
if (response.isSuccess()) {
// 如果登录成功
LOGIN.set(true);
}
// 唤醒 system in 线程
WAIT_FOR_LOGIN.countDown();
}
}
// 在连接建立后触发 active 事件
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
// 负责接收用户在控制台的输入，负责向服务器发送各种消息
new Thread(() -> {
System.out.println("请输入用户名:");
String username = scanner.nextLine();
if (EXIT.get()) {
return;
}
System.out.println("请输入密码:");
String password = scanner.nextLine();
if (EXIT.get()) {
return;
}
// 构造消息对象
LoginRequestMessage message = new LoginRequestMessage(username, password);
System.out.println(message);
// 发送消息
ctx.writeAndFlush(message);
System.out.println("等待后续操作...");
try {
WAIT_FOR_LOGIN.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
// 如果登录失败
if (!LOGIN.get()) {
ctx.channel().close();
return;
}
while (true) {
System.out.println("==================================");
System.out.println("send [username] [content]");
System.out.println("gsend [group name] [content]");
System.out.println("gcreate [group name] [m1,m2,m3...]");
System.out.println("gmembers [group name]");
System.out.println("gjoin [group name]");
System.out.println("gquit [group name]");
System.out.println("quit");
System.out.println("==================================");
String command = null;
try {
command = scanner.nextLine();
} catch (Exception e) {
break;
}
if (EXIT.get()) {
return;
}
String[] s = command.split(" ");
switch (s[0]) {
case "send":
ctx.writeAndFlush(new ChatRequestMessage(username, s[1], s[2]));
break;
case "gsend":
ctx.writeAndFlush(new GroupChatRequestMessage(username, s[1], s[2]));
break;
case "gcreate":
Set<String> set = new HashSet<>(Arrays.asList(s[2].split(",")));
set.add(username); // 加入自己
ctx.writeAndFlush(new GroupCreateRequestMessage(s[1], set));
break;
case "gmembers":
ctx.writeAndFlush(new GroupMembersRequestMessage(s[1]));
break;
case "gjoin":
ctx.writeAndFlush(new GroupJoinRequestMessage(username, s[1]));
break;
case "gquit":
ctx.writeAndFlush(new GroupQuitRequestMessage(username, s[1]));
break;
case "quit":
ctx.channel().close();
return;
}
}
}, "system in").start();
}
// 在连接断开时触发
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
log.debug("连接已经断开，按任意键退出..");
EXIT.set(true);
}
// 在出现异常时触发
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
log.debug("连接已经断开，按任意键退出..{}", cause.getMessage());
EXIT.set(true);
}
});
}
});
Channel channel = bootstrap.connect("localhost", 8080).sync().channel();
channel.closeFuture().sync();
} catch (Exception e) {
log.error("client error", e);
} finally {
group.shutdownGracefully();
}
}3. 服务端代码
服务器端将handler独立出来
java
public static void main(String[] args) throws InterruptedException {
NioEventLoopGroup group = new NioEventLoopGroup();
ServerBootstrap serverBootstrap = new ServerBootstrap();
LoggingHandler loggingHandler = new LoggingHandler(LogLevel.INFO);
try {
serverBootstrap.group(group);
serverBootstrap.channel(NioServerSocketChannel.class);
serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(loggingHandler);
/**
* TODO 添加业务handler
*/
}
});
ChannelFuture channelFuture = serverBootstrap.bind("192.168.101.1", 8080);
channelFuture.channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}4. 聊天室业务-单聊
java
@ChannelHandler.Sharable
public class LoginRequestMessageHandler extends SimpleChannelInboundHandler<LoginRequestMessage> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, LoginRequestMessage msg) throws Exception {
String username = msg.getUsername();
String password = msg.getPassword();
boolean login = UserServiceFactory.getUserService().login(username, password);
LoginResponseMessage message;
if(login) {
SessionFactory.getSession().bind(ctx.channel(), username);
message = new LoginResponseMessage(true, "登录成功");
} else {
message = new LoginResponseMessage(false, "用户名或密码不正确");
}
ctx.writeAndFlush(message);
}
}
java
@ChannelHandler.Sharable
public class ChatRequestMessageHandler extends SimpleChannelInboundHandler<ChatRequestMessage> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, ChatRequestMessage msg) throws Exception {
String to = msg.getTo();
Channel channel = SessionFactory.getSession().getChannel(to);
// 在线
if(channel != null) {
channel.writeAndFlush(new ChatResponseMessage(msg.getFrom(), msg.getContent()));
}
// 不在线
else {
ctx.writeAndFlush(new ChatResponseMessage(false, "对方用户不存在或者不在线"));
}
}
}
5. 聊天室业务-群聊
java
@ChannelHandler.Sharable
public class GroupCreateRequestMessageHandler extends SimpleChannelInboundHandler<GroupCreateRequestMessage> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, GroupCreateRequestMessage msg) throws Exception {
String groupName = msg.getGroupName();
Set<String> members = msg.getMembers();
// 群管理器
GroupSession groupSession = GroupSessionFactory.getGroupSession();
Group group = groupSession.createGroup(groupName, members);
if (group == null) {
// 发生成功消息
ctx.writeAndFlush(new GroupCreateResponseMessage(true, groupName + "创建成功"));
// 发送拉群消息
List<Channel> channels = groupSession.getMembersChannel(groupName);
for (Channel channel : channels) {
channel.writeAndFlush(new GroupCreateResponseMessage(true, "您已被拉入" + groupName));
}
} else {
ctx.writeAndFlush(new GroupCreateResponseMessage(false, groupName + "已经存在"));
}
}
}
java
@ChannelHandler.Sharable
public class GroupChatRequestMessageHandler extends SimpleChannelInboundHandler<GroupChatRequestMessage> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, GroupChatRequestMessage msg) throws Exception {
List<Channel> channels = GroupSessionFactory.getGroupSession()
.getMembersChannel(msg.getGroupName());
for (Channel channel : channels) {
channel.writeAndFlush(new GroupChatResponseMessage(msg.getFrom(), msg.getContent()));
}
}
}
java
@ChannelHandler.Sharable
public class GroupJoinRequestMessageHandler extends SimpleChannelInboundHandler<GroupJoinRequestMessage> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, GroupJoinRequestMessage msg) throws Exception {
Group group = GroupSessionFactory.getGroupSession().joinMember(msg.getGroupName(), msg.getUsername());
if (group != null) {
ctx.writeAndFlush(new GroupJoinResponseMessage(true, msg.getGroupName() + "群加入成功"));
} else {
ctx.writeAndFlush(new GroupJoinResponseMessage(true, msg.getGroupName() + "群不存在"));
}
}
}
java
@ChannelHandler.Sharable
public class GroupQuitRequestMessageHandler extends SimpleChannelInboundHandler<GroupQuitRequestMessage> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, GroupQuitRequestMessage msg) throws Exception {
Group group = GroupSessionFactory.getGroupSession().removeMember(msg.getGroupName(), msg.getUsername());
if (group != null) {
ctx.writeAndFlush(new GroupJoinResponseMessage(true, "已退出群" + msg.getGroupName()));
} else {
ctx.writeAndFlush(new GroupJoinResponseMessage(true, msg.getGroupName() + "群不存在"));
}
}
}
java
@ChannelHandler.Sharable
public class GroupMembersRequestMessageHandler extends SimpleChannelInboundHandler<GroupMembersRequestMessage> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, GroupMembersRequestMessage msg) throws Exception {
Set<String> members = GroupSessionFactory.getGroupSession()
.getMembers(msg.getGroupName());
ctx.writeAndFlush(new GroupMembersResponseMessage(members));
}
}
6. 聊天室业务-退出
java
@ChannelHandler.Sharable
public class QuitHandler extends ChannelInboundHandlerAdapter {
// 当连接断开时触发 inactive 事件
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
SessionFactory.getSession().unbind(ctx.channel());
log.debug("{} 已经断开", ctx.channel());
}
// 当出现异常时触发
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
SessionFactory.getSession().unbind(ctx.channel());
log.debug("{} 已经异常断开 异常是{}", ctx.channel(), cause.getMessage());
}
}7. 聊天室业务-空闲检测
在实际使用中需要处理连接假死的情况，假死的原因有：
- 网络设备出现故障，例如网卡，机房等，底层的TCP连接已经断开了，但应用程序没有感知到，仍然占用着资源。
- 公网网络不稳定，出现丢包。如果连续出现丢包，这时现象就是客户端数据发不出去，服务端也一直收不到数据，就这么一直耗着。
- 应用程序线程阻塞，无法进行数据读写。
导致的问题：
- 假死的连接占用的资源不能自动释放。
- 向假死的连接发送数据，得到的反馈是发送超时。
服务器端解决方案：如果能收到客户端数据，说明没有假死。因此策略就可以定为，每隔一段时间就检查这段时间内是否接收到客户端数据，没有就可以判定为连接假死。但如果用户在登录的过程中，或者用户在线并没有聊天的情形下并不能统一认为客户端就是假死。因此在客户端设置一个定时周期任务发送心跳检测消息给服务器。
java
// 用来判断是不是 读空闲时间过长，或 写空闲时间过长
// 5s 内如果没有收到 channel 的数据，会触发一个 IdleState#READER_IDLE 事件
ch.pipeline().addLast(new IdleStateHandler(5, 0, 0));
// ChannelDuplexHandler 可以同时作为入站和出站处理器
ch.pipeline().addLast(new ChannelDuplexHandler() {
// 用来触发特殊事件
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception{
IdleStateEvent event = (IdleStateEvent) evt;
// 触发了读空闲事件
if (event.state() == IdleState.READER_IDLE) {
log.debug("已经 5s 没有读到数据了");
ctx.channel().close();
}
}
});
java
// 用来判断是不是 读空闲时间过长，或 写空闲时间过长
// 3s 内如果没有向服务器写数据，会触发一个 IdleState#WRITER_IDLE 事件
ch.pipeline().addLast(new IdleStateHandler(0, 3, 0));
// ChannelDuplexHandler 可以同时作为入站和出站处理器
ch.pipeline().addLast(new ChannelDuplexHandler() {
// 用来触发特殊事件
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception{
IdleStateEvent event = (IdleStateEvent) evt;
// 触发了写空闲事件
if (event.state() == IdleState.WRITER_IDLE) {
// log.debug("3s 没有写数据了，发送一个心跳包");
ctx.writeAndFlush(new PingMessage());
}
}
});
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