【OpenAI&SK】：百行行代码实现GPT的chat

　　SemanticKernel其中一个功能是实现像https://chat.openai.com那样的问答聊天功能，给过SK封装，就变得简单灵活了，下面是不到百地代码实现的一个简单聊天功能。

　　32行(后端)+51行(前端)=83行

　　后端：

using Microsoft.SemanticKernel;
using Microsoft.SemanticKernel.AI.ChatCompletion;
using Microsoft.SemanticKernel.Connectors.AI.OpenAI.ChatCompletion;
using System.Text;
var key = File.ReadAllText(@"C:\\GPT\key.txt");
var builder = WebApplication.CreateBuilder(args);
var kernel = Kernel.Builder  
    .WithOpenAIChatCompletionService("gpt-4", key, serviceId: "gsw_chat")
    .Build();
var chatGPT = kernel.GetService<IChatCompletion>();
builder.Services.AddSingleton(chatGPT);
builder.Services.AddSingleton((OpenAIChatHistory)chatGPT.CreateNewChat());
var app = builder.Build();
app.UseStaticFiles();
app.MapGet("/chat", AskAsync);
app.Run();
async IAsyncEnumerable<string> AskAsync(IChatCompletion chat, OpenAIChatHistory history, string ask)
{
    history.AddUserMessage(ask);
    var reply = chat.GenerateMessageStreamAsync(history, new ChatRequestSettings() { MaxTokens = 2048 });
    var answer = new StringBuilder();
    await foreach (var item in reply)
    { 
        if(item==null)
        {
            continue;
        }
        answer.Append(item);
        yield return item;
    }
    history.AddAssistantMessage(answer.ToString());
}

　　首先构建一个KernelBuilder，把OpenAI的ChatCompletion服务添加到Builder中，然后把Chat服务注入到asp.net core的服务容器中，同时也把History列表注入到服务容器中，当前api有访问的时候，通过chat结合history来获取OpenAI返回的聊天信息，以流的形式输出到前端。

　　前端：

<!DOCTYPE html>
<html>
<head>
    <title>小助手</title>
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@5.2.3/dist/css/bootstrap.min.css">
</head>
<body>
    <div class="container">
        <div class="row">
            <h3 class="display-4">小助手</h3>
        </div>
        <div class="row">
            <div class="input-group mb-3">
                <input type="text" id="ask" class="form-control" placeholder="请输入问题" aria-label="请输入问题" aria-describedby="chat">
                <button class="btn btn-outline-secondary" type="button" id="chat">开始</button>
            </div>
        </div>
        <div id="messagesdiv" class="row"></div>
    </div>
    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
    <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.2.3/dist/js/bootstrap.bundle.min.js"></script>
    <script>
        $(function () {
            $("#chat").click(function () {
                var askDiv = $("<div class='alert alert-primary'>");
                askDiv.text("【您】" + $("#ask").val());
                var answerDiv = $("<textarea  class='alert alert-warning' style='min-height:150px'>");
                $("#messagesdiv").append(askDiv);
                $("#messagesdiv").append(answerDiv);               
                var xhr = new $.ajaxSettings.xhr();
                xhr.onreadystatechange = function () {
                    if (xhr.readyState == 3) {
                        var content = "";
                        var list = JSON.parse(xhr.responseText.replace(']', '') + ']');
                        $(list).each(function (index, item) {
                            content += item
                        })
                        answerDiv.text(content)
                    } else if (xhr.readyState == 4) {
                        answerDiv.removeClass("alert-warning")
                        answerDiv.addClass("alert-success")
                        $("#ask").val("")
                    }
                }
                xhr.open('GET', '/chat?ask=' + $("#ask").val())
                xhr.send()
            })
        });
</script>
</body>
</html>