一、WebSocket基础
1. WebSocket介绍
WebSocket是一种网络通信协议,提供全双工通信通道,允许服务器和客户端之间进行持久、双向的通信。与传统HTTP不同,WebSocket在建立连接后保持开放状态,双方可以随时发送数据。
2. WebSocket与HTTP比较
3. WebSocket工作原理
连接建立:客户端发送标准HTTP请求,请求头包含升级协议信息
GET /chat HTTP/1.1
Host: server.example.com
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==
Sec-WebSocket-Protocol: chat, superchat
Sec-WebSocket-Version: 13
握手确认:服务器同意升级,返回确认响应
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk=
Sec-WebSocket-Protocol: chat
双向通信:握手成功后,连接保持开放,双方可以随时发送数据帧
连接关闭:任一方可以发送关闭帧,终止连接
二、Spring Boot整合WebSocket示例(聊天室)
下面详细介绍使用Spring Boot创建WebSocket聊天室应用的步骤:
步骤1:创建Spring Boot项目
- 使用Spring Initializr创建项目
- 添加必要依赖:
- Spring Web
- WebSocket
- Lombok(可选,简化代码)
pom.xml依赖:
<dependencies><!-- Spring Boot Web --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><!-- WebSocket --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-websocket</artifactId></dependency><!-- Lombok(可选) --><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency>
</dependencies>
步骤2:创建WebSocket配置类
创建WebSocketConfig类:
package com.example.websocket.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;@Configuration
public class WebSocketConfig {@Beanpublic ServerEndpointExporter serverEndpointExporter() {return new ServerEndpointExporter();}
}
说明:
ServerEndpointExporter
负责注册使用@ServerEndpoint
注解的WebSocket端点- 该Bean将自动扫描和注册带有
@ServerEndpoint
注解的类
步骤3:定义消息实体类
创建Message类:
package com.example.websocket.model;import lombok.Data;@Data
public class Message {private String username; // 发送者用户名private String content; // 消息内容private String timestamp; // 时间戳// 如果不使用Lombok,需要添加getter、setter和构造方法
}
步骤4:创建WebSocket端点类
创建ChatEndpoint类:
package com.example.websocket.endpoint;import com.example.websocket.model.Message;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;@Component
@ServerEndpoint("/chat/{username}")
public class ChatEndpoint {private static final Logger logger = LoggerFactory.getLogger(ChatEndpoint.class);private static final Map<String, Session> onlineSessions = new ConcurrentHashMap<>();private static final ObjectMapper objectMapper = new ObjectMapper();/*** 连接建立时调用*/@OnOpenpublic void onOpen(Session session, @PathParam("us