【Unity】使用UnityWebRequest将Http升级到Https / 【报错】Curl error 51: Cert verify failed

以PUT为例

Http：

    private void PutTest(string url,string parame)
    {
        UnityWebRequest webRequest = new UnityWebRequest(url,UnityWebRequest.kHttpVerbPUT);

        byte[] databyte = Encoding.UTF8.GetBytes(parame);
        webRequest.uploadHandler = new UploadHandlerRaw(databyte);

        webRequest.downloadHandler = new DownloadHandlerBuffer();

        webRequest.timeout = 5;

        webRequest.SetRequestHeader("Content-Type","text/json;charset=utf-8");

        webRequest.SendWebRequest();
    }

如果直接把Url从"http"改为"https"，

会有报错："Curl error 51: Cert verify failed: UNITYTLS_X509VERIFY_FLAG_NOT_TRUSTED"，证书验证失败，因为没有指定证书，使用的平台使用默认证书验证，导致失败

可以通过设置WebRequest.certificateHandler来指定证书，CertificateHandler类的ValidateCertificate函数返回值是false。自定义子类继承CertificateHandler，重写ValidateCertificate函数，就可以成功验证证书了

public class WebRequestCertificate : CertificateHandler
{
    protected override bool ValidateCertificate(byte[] certificateData)
    {
        //return base.ValidateCertificate(certificateData);
        return true;
    }
}

Https：

    private void PutTest(string url,string parame)
    {
        UnityWebRequest webRequest = new UnityWebRequest(url,UnityWebRequest.kHttpVerbPUT);

        byte[] databyte = Encoding.UTF8.GetBytes(parame);
        webRequest.uploadHandler = new UploadHandlerRaw(databyte);
        webRequest.downloadHandler = new DownloadHandlerBuffer();
        webRequest.timeout = 5;

        //拥有对CertificateHandler对象的引用，该对象可管理此UnityWebRequest的证书验证
        webRequest.certificateHandler = new WebRequestCertificate();

        webRequest.SetRequestHeader("Content-Type","text/json;charset=utf-8");
        webRequest.SendWebRequest();
    }