利用springboot-websocket 和Tomcat-websocket 实现websocket 客户端 并支持wss协议 ssl证书认证

在Spring Boot中利用WebSocket功能，通常会结合Spring Websocket库和WebSocket客户端库，例如`org.springframework.web.reactive.socket.client.WebSocketClient`，来实现实时通信。对于HTTPS（wss）的支持，需要配置SSL/TLS证书。

首先，你需要在Spring Boot项目中添加依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>

然后，在`application.yml`或`application.properties`文件中配置WebSocket服务器地址和SSL相关的设置：

server:
  port: 8443 # 如果你的服务器在非标准端口运行
  servlet:
    context-path: /your-context-path
  ssl:
    key-store: classpath:keystore.jks
    key-store-password: your-password
    keyAlias: your-key-alias

spring:
  application:
    name: your-app-name
  webflux:
    websocket:
      clients:
        default:
          uri: wss://your-backend-url/websocket

创建WebSocket客户端：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.http.HttpHeaders;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Component;
import org.springframework.util.Assert;
import org.springframework.web.reactive.function.client.WebClient;

@Component
public class WebSocketClient {

    private final ApplicationContext context;
    
    @Autowired
    public WebSocketClient(ApplicationContext context) {
        this.context = context;
    }

    public Mono<Void> sendMessage(String message) {
        // 获取当前用户凭据
        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON);

        // 添加WS-Security header if needed (for SSL)
        String user = auth.getName(); // 假设用户名已经从token解析出来
        headers.set("Sec-WebSocket-Protocol", "your-custom-subprotocol");
        headers.setBasicAuth(user, "your-password");

        return WebClient.create(context.getBean("uri", URI.class))
                .header(HttpHeaders.HOST, "your-backend-url")
                .headers(headers)
                .post()
                .retrieve()
                .bodyToMono(Void.class);
    }
}

当客户端尝试连接时，Spring Security会对连接请求进行验证。如果证书有效并且连接到的是正确的URL，那么连接将成功并可以开始发送和接收消息。