C# 将用户名和密码传递给Web API

我有一个角度2的方法：

login(usernameparam: string, passwordparam: string): Observable<boolean> {
    let headers = new Headers({
        'Content-Type': 'application/x-www-form-urlencoded', 'Accept-Charset': 'utf-16', 'Access-Control': 'Allow - Origin'
    });
    let options = new RequestOptions({ headers: headers });

    return this.http.post('http://localhost:64116/token',
        { username : usernameparam, password: passwordparam },
        options)
        .map((response: Response) => {
            // login successful if there's a jwt token in the response
            debugger;
            let token = response.json() && response.json().token;
            if (token) {
                this.token = token;

                localStorage.setItem('currentUser', JSON.stringify({ username: usernameparam, token: token }));
                return true;
            } else {
                return false;
            }
        });
}

---

但是，当我收到HttpContext时，用户名和密码都是空的。当查看来自浏览器的请求时，它清楚地指出，表单数据包含这两个。我遗漏了什么？

能否显示F11工具中的表单数据？

private async Task GenerateToken(HttpContext context)
{
    var username = context.Request.Form["username"];
    var password = context.Request.Form["password"];

    // The rest of the method
}