SpringBoot整合SSE，基于okhttp

一、引入依赖

<dependency>
    <groupId>com.squareup.okhttp3</groupId>
    <artifactId>okhttp</artifactId>
    <version>4.10.0</version>
</dependency>
<dependency>
    <groupId>com.squareup.okhttp3</groupId>
    <artifactId>okhttp-sse</artifactId>
    <version>4.10.0</version>
</dependency>

二、创建 SSE 客户端服务类

import okhttp3.*;
import okhttp3.sse.EventSource;
import okhttp3.sse.EventSourceListener;
import okhttp3.sse.EventSources;
import org.springframework.stereotype.Service;

import java.util.concurrent.TimeUnit;

@Service
public class SseClientService {

    private final OkHttpClient okHttpClient;
    private EventSource eventSource;

    public SseClientService() {
        this.okHttpClient = new OkHttpClient.Builder()
                .connectTimeout(10, TimeUnit.SECONDS)
                .readTimeout(0, TimeUnit.SECONDS) // 0表示不超时
                .writeTimeout(10, TimeUnit.SECONDS)
                .build();
    }

    public void connectToSseServer(String url) {
        Request request = new Request.Builder()
                .url(url)
                .build();

        EventSource.Factory factory = EventSources.createFactory(okHttpClient);
        
        this.eventSource = factory.newEventSource(request, new EventSourceListener() {
            @Override
            public void onOpen(EventSource eventSource, Response response) {
                System.out.println("SSE连接已建立");
            }

            @Override
            public void onEvent(EventSource eventSource, String id, String type, String data) {
                System.out.printf("收到事件: id=%s, type=%s, data=%s%n", id, type, data);
                // 在这里处理收到的数据
            }

            @Override
            public void onClosed(EventSource eventSource) {
                System.out.println("SSE连接已关闭");
            }

            @Override
            public void onFailure(EventSource eventSource, Throwable t, Response response) {
                System.err.println("SSE连接失败: " + t.getMessage());
                // 可以在这里实现重连逻辑
                reconnect(url);
            }
        });
    }

    private void reconnect(String url) {
        try {
            Thread.sleep(5000); // 5秒后重连
            connectToSseServer(url);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }

    public void closeConnection() {
        if (eventSource != null) {
            eventSource.cancel();
        }
        okHttpClient.dispatcher().executorService().shutdown();
    }
}

三、 创建控制器测试

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/sse-client")
public class SseClientController {

    private final SseClientService sseClientService;

    public SseClientController(SseClientService sseClientService) {
        this.sseClientService = sseClientService;
    }

    @GetMapping("/connect")
    public String connect() {
        // 连接到SSE服务器（可以是另一个Spring Boot应用的SSE端点）
        sseClientService.connectToSseServer("http://localhost:8080/sse-server/subscribe");
        return "SSE客户端已启动";
    }

    @GetMapping("/disconnect")
    public String disconnect() {
        sseClientService.closeConnection();
        return "SSE客户端已关闭";
    }
}

四、 高级功能实现

1. 自定义事件处理

// 在EventSourceListener中添加更多事件处理
@Override
public void onEvent(EventSource eventSource, String id, String type, String data) {
    switch (type) {
        case "message":
            handleMessageEvent(data);
            break;
        case "system-alert":
            handleSystemAlert(data);
            break;
        default:
            handleDefaultEvent(data);
    }
}

2. 添加认证头

public void connectToSseServerWithAuth(String url, String token) {
    Request request = new Request.Builder()
            .url(url)
            .header("Authorization", "Bearer " + token)
            .build();
    
    // 其余代码与基础实现相同
}

3. 心跳检测

@Override
public void onEvent(EventSource eventSource, String id, String type, String data) {
    if ("heartbeat".equals(type)) {
        System.out.println("收到心跳: " + data);
        return;
    }
    // 处理其他事件
}

五、OkHttpConfig单独配置

import okhttp3.OkHttpClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.concurrent.TimeUnit;

@Configuration
public class OkHttpConfig {

    @Bean
    public OkHttpClient okHttpClient() {
        return new OkHttpClient.Builder()
                .connectTimeout(15, TimeUnit.SECONDS)
                .readTimeout(0, TimeUnit.SECONDS) // 0表示不超时
                .writeTimeout(15, TimeUnit.SECONDS)
                .retryOnConnectionFailure(true)
                .build();
    }
}