Python与Go实现服务器发送事件(SSE)详解：协议、代码与调试

Content-Type: text/event-stream
Cache-Control: no-cache
Connection: keep-alive

from flask import Flask, Response

app = Flask(__name__)


@app.route('/events')
def sse_handler():
    def generate():
        paragraph = [
            "Hello, this is an example of a continuous text output.",
            "It contains multiple sentences, each of which will be sent to the client as an event.",
            "This is to simulate the functionality of Server-Sent Events (SSE).",
            "We can use this method to push real-time updates.",
            "End of sample text, thank you!",
        ]

        for sentence in paragraph:
            yield f"data: {sentence}\n\n"

            import time
            time.sleep(1)

    return Response(generate(), mimetype='text/event-stream')


if __name__ == '__main__':
    app.run(host='0.0.0.0', port=8081, debug=True)

package main

import (
    "fmt"
    "log"
    "net/http"
    "time"
)

func main() {
    http.HandleFunc("/events", sseHandler)

    fmt.Println("Starting server on :8080")
    if err := http.ListenAndServe(":8080", nil); err != nil {
        log.Fatalf("Server error: %v", err)
    }
}

func sseHandler(w http.ResponseWriter, r *http.Request) {
    flusher, ok := w.(http.Flusher)
    if !ok {
        http.Error(w, "Streaming unsupported!", http.StatusInternalServerError)
        return
    }

    w.Header().Set("Content-Type", "text/event-stream")
    w.Header().Set("Cache-Control", "no-cache")
    w.Header().Set("Connection", "keep-alive")

    // Change the output here to a specific text
    paragraph := []string{
        "Hello, this is an example of a continuous text output.",
        "It contains multiple sentences, each of which will be sent to the client as an event.",
        "This is to simulate the functionality of Server-Sent Events (SSE).",
        "We can use this method to push real-time updates.",
        "End of sample text, thank you!",
    }

    for _, sentence := range paragraph {
        _, err := fmt.Fprintf(w, "data: %s\n\n", sentence)
        if err != nil {
            return
        }
        flusher.Flush()
        time.Sleep(1 * time.Second) // Wait 1 second before sending the next piece of text
    }
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>SSE Example 🌟</title>
</head>
<body>
    <h1>Server-Sent Events Example 🚀</h1>
    <div id="messages"></div>
    <script>
        window.onload = function() {
            if (typeof(EventSource) !== "undefined") {
                const eventSource = new EventSource('/events');

                eventSource.onmessage = function(event) {
                    const newElement = document.createElement("p");
                    newElement.textContent = "Message: " + event.data;

                    document.getElementById("messages").appendChild(newElement);
                };

                eventSource.onerror = function(event) {
                    console.error("Error occurred: ", event);
                    const newElement = document.createElement("p");
                    newElement.textContent = "An error occurred while connecting to the event source.";
                    document.getElementById("messages").appendChild(newElement);
                    eventSource.close(); 
                };
            } else {
                document.getElementById("messages").textContent = "Sorry, your browser does not support server-sent events...";
            }
        };
    </script>
</body>
</html>