ASP.NET CORE下用盛派微信SDK取微信openid

在ASP.NET Core下使用盛派微信SDK获取微信openid的步骤如下：

1. 在`Startup.cs`文件中配置服务，添加`WeChatConfig`类用于存储微信配置信息：

public class WeChatConfig
{
    public string AppId { get; set; }
    public string AppSecret { get; set; }
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        // 添加WeChatConfig服务
        services.Configure<WeChatConfig>(Configuration.GetSection("WeChatConfig"));

        // 添加WeChatProvider服务
        services.AddScoped<IWeChatProvider, WeChatProvider>();
    }
}

2. 配置`appsettings.json`文件，添加微信配置信息：

{
    "WeChatConfig": {
        "AppId": "your_appid",
        "AppSecret": "your_appsecret"
    }
}

3. 创建`WeChatController`，在`Action`方法中调用`IWeChatProvider`接口的`GetOpenIdAsync`方法获取用户的openid：

[Route("wechat")]
public class WeChatController : Controller
{
    private readonly IWeChatProvider _weChatProvider;
    private readonly ILogger<WeChatController> _logger;

    public WeChatController(IWeChatProvider weChatProvider, ILogger<WeChatController> logger)
    {
        _weChatProvider = weChatProvider;
        _logger = logger;
    }

    [Route("callback")]
    public async Task<IActionResult> Callback(string code)
    {
        try
        {
            var openId = await _weChatProvider.GetOpenIdAsync(code);
            // 处理openid
            return Ok(openId);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "获取openid失败");
            return BadRequest();
        }
    }
}

4. 实现`IWeChatProvider`接口，调用盛派微信SDK的`GetOpenIdAsync`方法：

public interface IWeChatProvider
{
    Task<string> GetOpenIdAsync(string code);
}

public class WeChatProvider : IWeChatProvider
{
    private readonly WeChatConfig _weChatConfig;

    public WeChatProvider(IOptions<WeChatConfig> options)
    {
        _weChatConfig = options.Value;
    }

    public async Task<string> GetOpenIdAsync(string code)
    {
        var weChatApi = new WeChatApi(_weChatConfig.AppId, _weChatConfig.AppSecret);
        var tokenResult = await weChatApi.GetAccessTokenAsync(code);
        var userInfoResult = await weChatApi.GetUserInfoAsync(tokenResult.access_token, tokenResult.openid);
        return userInfoResult.openid;
    }
}

以上就是在ASP.NET Core下使用盛派微信SDK获取微信openid的步骤。需要注意的是，获取用户openid需要用户授权，因此需要在微信公众平台中配置授权回调域名，并在前端页面中调用微信授权接口获取code参数。