.NET 6 - Build Line Notify Web API

文章目錄

此篇文章將會透過 .NET 6 來實作Line Notify，傳送文字、貼圖與相片至Line。

詳細的Line API規格請至Line官方文件查詢。

Implementation

1. Line Notify服務申請

自Line Notify申請服務以取得Client ID、Client Secret，並設定Callback URL。

Line Notify申請服務

2. 基本設定

  • 在appsettings.json中，設定client_id、client_secret、redirect_uri。
"LineNotifySetting": {
    "client_id": "...",      // Client ID
    "client_secret": "...",  // Client Secret
    "redirect_uri": "http://localhost:4200" // Callback URL
},
  • 建立資料模型(data model)。
public class LineNotifySetting
{
    public string Client_ID { get; set; } = null!;
    public string Client_Secret { get; set; } = null!;
    public string Redirect_URI { get; set; } = null!;
}
  • 建立服務(service)。
    • 宣告欲使用的LINE Notify API。
    • 注入IConfiguration，以取得appsettings.json中的LineNotifySetting。
    • 注入IHttpClientFactory，並在program.cs中呼叫AddHttpClient方法進行註冊，以建立HttpClient執行個體來發送Http請求。
      // Add HttpClient service
builder.Services.AddHttpClient();

public class LineNotifyService
{
    private const string LineAuthorizeAPI = "https://notify-bot.line.me/oauth/authorize";
    private const string LineTokenAPI = "https://notify-bot.line.me/oauth/token";
    private const string LineNotifyAPI = "https://notify-api.line.me/api/notify";
    private const string LineRevokeAPI = "https://notify-api.line.me/api/revoke";

    private readonly IConfiguration _configuration;
    private readonly LineNotifySetting _lineNotifySetting = new LineNotifySetting();
    private readonly IHttpClientFactory _httpClientFactory;

    public LineNotifyService(IConfiguration configuration, IHttpClientFactory httpClientFactory)
    {
        _configuration = configuration;
        _lineNotifySetting.Client_ID = _configuration["LineNotifySetting:client_id"];
        _lineNotifySetting.Client_Secret = _configuration["LineNotifySetting:client_secret"];
        _lineNotifySetting.Redirect_URI = _configuration["LineNotifySetting:redirect_uri"];
        _httpClientFactory = httpClientFactory;
    }
}

2. 導向Line Notify授權網頁

將使用者導向Line Notify服務授權之頁面。

使用者授權使用Line Notify服務使用者授權使用Line Notify服務

  • LineNotifyService.cs

    public string GetAuthorizationUrl(string name)
{
    var URL = LineAuthorizeAPI;
    URL += "?response_type=code";
    URL += $"&client_id={_lineNotifySetting.Client_ID}";
    URL += $"&redirect_uri={_lineNotifySetting.Redirect_URI}";
    URL += "&scope=notify";
    URL += $"&state={name}";
    URL += "&response_mode=form_post";
    return URL;
}

  • LineNotifyController.cs

    [HttpGet("{name}")]
public IActionResult GetAuthorizationUrl(string name)
{
    var URL = _lineNotifyService.GetAuthorizationUrl(name);
    return Ok(Content(URL));
}

3. 取得AccessToken

授權成功後，將自動導向至服務路徑(redirect_uri)，並帶有兩參數code與state。該服務路徑應自動發送Post請求，透過code來取得AccessToken。此範例將取得的AccessToken傳回前台，實務上應將取得的AccessToken存入資料庫。 取得Line AccessToken

  • LineNotifyService.cs

    public async Task<HttpResponseMessage> PostTokenAsync(string code)
{
    HttpClient client = _httpClientFactory.CreateClient();
    client.Timeout = new TimeSpan(0, 0, 60);

    var content = new FormUrlEncodedContent(new[]
    {
        new KeyValuePair<string, string>("grant_type", "authorization_code"),
        new KeyValuePair<string, string>("code", code),
        new KeyValuePair<string, string>("redirect_uri", _lineNotifySetting.Redirect_URI),
        new KeyValuePair<string, string>("client_id", _lineNotifySetting.Client_ID),
        new KeyValuePair<string, string>("client_secret", _lineNotifySetting.Client_Secret)
    });
    return await client.PostAsync(LineTokenAPI, content);
}

  • LineNotifyController.cs

    [HttpPost]
public async Task<IActionResult> PostTokenAsync([FromBody] LineAuthRes authRes)
{
    try
    {
        var res = await _lineNotifyService.PostTokenAsync(authRes.Code);
        var msg = await res.Content.ReadAsStringAsync();
        return StatusCode((int)res.StatusCode, msg);
    }
    catch (Exception ex)
    {
        return StatusCode((int)HttpStatusCode.InternalServerError, ex.Message);
    }
}

  • LineAuthRes.cs

    public class LineAuthRes
{
    public string Code { get; set; } = null!;
    public string State { get; set; } = null!;
}

4. 發送訊息

在Header加上Authorization Bearer <access_token>，以發送Line訊息；認證方式為Bearer，憑證則為使用者的Access Token。

訊息可為一般文字、貼圖或相片，但須注意message參數不可為空。

發送Line訊息

  • LineNotifyService.cs

    public async Task<HttpResponseMessage> SendAsync(string token, LineSendInfo info)
{
    HttpClient client = _httpClientFactory.CreateClient();
    client.Timeout = new TimeSpan(0, 0, 60);
    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);

    var uri = $"{LineNotifyAPI}?message={info.Message}";
    if (info.StickerPackageId != null) uri = $"{uri}&stickerPackageId={info.StickerPackageId}"; 
    if (info.StickerId != null) uri = $"{uri}&stickerId={info.StickerId}";

    var content = new MultipartFormDataContent();
    if (info.ImageFile != null)
    {
        if(info.ImageFile.Length > 0)
        {
            using (var ms = new MemoryStream())
            {
                await info.ImageFile.CopyToAsync(ms);
                var baContent = new ByteArrayContent(ms.ToArray());
                content.Add(baContent, "imageFile", info.ImageFile.FileName);
            }
        }
    }
    else
    {
        content = null;
    }

    return await client.PostAsync(uri, content);
}

  • LineNotifyController.cs

    [HttpPost("Notify")]
public async Task<IActionResult> PostMessageAsync(string token, [FromForm] LineSendInfo info)
{
    try
    {
        var res = await _lineNotifyService.SendAsync(token, info);
        var msg = await res.Content.ReadAsStringAsync();
        return StatusCode((int)res.StatusCode, msg);
    }
    catch (Exception ex)
    {
        return StatusCode((int)HttpStatusCode.InternalServerError, ex.Message);
    }
}

  • LineSendInfo.cs

    public class LineSendInfo
{
    public string Message { get; set; } = null!;
    public IFormFile? ImageFile { get; set; }
    public string? StickerPackageId { get; set; }
    public string? StickerId { get; set; }
}

5. 撤消AccessToken

  • LineNotifyService.cs

    public async Task<HttpResponseMessage> RevokeToken(string token)
{
    HttpClient client = _httpClientFactory.CreateClient();
    client.Timeout = new TimeSpan(0, 0, 60);
    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);

    return await client.PostAsync(LineRevokeAPI, null);
}

  • LineNotifyController.cs

    [HttpPost("Revoke")]
public async Task<IActionResult> RevokeAsync(string token)
{
    try
    {
        var res = await _lineNotifyService.RevokeToken(token);
        var msg = await res.Content.ReadAsStringAsync();
        return StatusCode((int)res.StatusCode, msg);
    }
    catch (Exception ex)
    {
        return StatusCode((int)HttpStatusCode.InternalServerError, ex.Message);
    }
}

參考資料

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