用php实现stream模式

首先是前端的代码是：

var url = "https://www.example.com";
fetch(url, {
    method: 'POST',
    headers: {
        'Content-Type': 'application/json'
    },
    body: JSON.stringify(requestData),
}).then(response => {
    const reader = response.body.getReader();
    return new ReadableStream({
        start(controller2) {
            function push() {
                reader.read().then(({
                    value,
                    done
                }) => {
                    if (done) {
                        controller2.close();
                        return;
                    }
                    controller2.enqueue(value);
                    push();
                })
            }
            push();
        }
    });
}).then(str	const reader = stream.getReader();
    reader.read().then(function processResult(result) {
        if (result.done) {
        	console.log("finish");
            return;
        }
        const chunk = decoder.decode(result.value, {
            stream: true
        });
        console.log(chunk);
        return reader.read().then(processResult);
    });
}).catch(error => console.error(`Error fetching stream: 

　PHP端代码是：

    public function stream_gpt()
    {
        if (ob_get_level() > 0) {
            ob_end_clean(); 
        }
        header('Content-Type: text/event-stream');
        header('Cache-Control: no-cache');
        header('Connection: keep-alive');
        header('X-Accel-Buffering: no');
        echo "XXXX";
        flush();

        die();
    }

　PHP通过stream调用远端服务

        $post_params = input();    
        $opts = array(
            'http' => array(
                'method'  => 'POST',
                'header'  => 'Content-type: application/json',
                'content' => json_encode($post_params)
            ),
        );
        $context = stream_context_create($opts);

        $remoteUrl = 'https://www.example.com';
        $handle = fopen($remoteUrl, 'r', false, $context);

        while (!feof($handle)) {
            echo fgets($handle,4);
            flush();
        }
        fclose($handle);

　如果出现错误“422 unprocessable entity”，应该是post json的参数格式不对造成的，请调整http post的content参数，应该是string（json）格式