c#中winform程序如何调用webapi接口？附源码

我们开发winform程序时，通常使用传统的三层结构，包括：数据层、业务层、页面层。Form页面调用时，直接new个Service类，实现业务需求。但这种模式有个弊端，就是业务逻辑全部放到了客户端。这样操作对客户端的机器要求很高，又很容易被攻击或源码泄露。因此，越来越多的winform项目，也通过webapi接口实现业务逻辑。

1、定义webapi接口

我们先定义好两个webapi接口，一个get访问、另一个post访问。在vs中创建webapi的教程请参考这篇博客。开发、调试和部署完成后。我们就可以写winform端的代码了。
https://webapi2.navisoft.com.cn/api/DatumApi/TestHttpGet
https://webapi2.navisoft.com.cn/api/DatumApi/TestHttpPost

2、实现get访问

我们使用WebClient这个对象即可

2.1、调用代码如下

//get访问
string urlPath = @"https://webapi2.navisoft.com.cn/api/DatumApi/TestHttpGet?queryParams=hello-vincent.q";
string modelRes = UrlHelper.WebMethodGetData(urlPath);

2.2、返回结果

{"code":"0","msg":"访问成功,时间:2022-09-24 17:38:23","msgEx":null,"stackTrace":null,"actionName":null,"content":"Query参数hello-vincent.q","apiinfoJson":null}

3、实现post访问

这个代码有些复杂，因为要定义的参数的传输格式，就是如何接收和获取？推荐使用application/json和application/x-www-form-urlencoded这两种格式。

3.1、调用代码如下

DatumOpenApiQueryModel modelP = new DatumOpenApiQueryModel()
{
    openId = "id1",
    nickName = "name1",
    text = "text1",
    param1 = "param1",
    actionName = "action1"
};
string jsonP = JsonHelper.GetJsonByObject(modelP);
string urlPath = @"https://webapi2.navisoft.com.cn/api/DatumApi/TestHttpPost";
string modelRes = UrlHelper.WebMethodPostData(urlPath, jsonP, "utf-8", "application/json");

3.2、返回结果

{"code":"0","msg":"访问成功,时间:2022-09-24 17:12:43","msgEx":null,"stackTrace":null,"actionName":null,"content":"Form参数{\"openId\":\"id1\",\"nickName\":\"name1\",\"actionName\":\"action1\",\"text\":\"text1\",\"param1\":\"param1\",\"openPlat\":null,\"imageBase64\":null,\"imageBase64_2\":null,\"audioBase64\":null,\"fileBase64\":null,\"fileName\":null,\"productKind\":null,\"queryName\":null,\"quickSearch\":null,\"productName\":null,\"accessToken\":null,\"accessProductCode\":null,\"accessProductVersion\":null,\"wxUserCode\":null,\"wxAccessToken\":null,\"currentUserCode\":null,\"currentUserName\":null,\"logonType\":0,\"recordCount\":0,\"pageInfo\":null,\"orderBys\":{}}","apiinfoJson":null}

4、如何实现？

如何实现get和post访问的代码如下所示，也不是很复杂吧？

/// <summary>
/// 提交GET方法至指定的Url,解析返回的数据
/// </summary>
/// <param name="url"></param>
/// <param name="charset"></param>
/// <returns></returns>
[ShortDescription("根据Get方式请求URL下载数据")]
public static string WebMethodGetData(string url, string charset = "utf-8")
{
    WebResponse response = null;
    Stream receiveStream = null;

    try
    {
        WebClientEx wc = new WebClientEx();
        byte[] byteResponse = wc.DownloadData(url);
        wc.Dispose();   //及时释放、避免第二次下载时、奇怪的"操作超时"的问题

        //字符集为UTF8
        string responseStr = Encoding.GetEncoding(charset).GetString(byteResponse);
        return responseStr;
    }
    catch (WebException ex)
    {
        string errorMessage = ex.Message;

        //需判断response是否==null
        response = ex.Response;
        if (response == null)
        {
            dynamic objErrorData = new { message = errorMessage, subErrors = "" };
            string jsonErrorData = JsonHelper.GetJsonByObject(objErrorData);
            throw new CustomApiJsonException(jsonErrorData, url, ex);
        }
        else
        {
            receiveStream = response.GetResponseStream();
            Encoding encode = Encoding.GetEncoding(charset);
            StreamReader sr = new StreamReader(receiveStream, encode);
            char[] readbuffer = new char[2048];
            int n = sr.Read(readbuffer, 0, 2048);

            string result = string.Empty;
            while (n > 0)
            {
                string str = new string(readbuffer, 0, n);
                result += str;
                n = sr.Read(readbuffer, 0, 2048);
            }
            response.Close();

            //此处将错误信息和json信息同时返回
            dynamic objErrorData = new { message = errorMessage, subErrors = result };
            string jsonErrorData = JsonHelper.GetJsonByObject(objErrorData);
            throw new CustomApiJsonException(jsonErrorData, url, ex);
        }
    }
    finally
    {
        //使用完后、释放资源
        if (response != null) response.Close();
        if (receiveStream != null) receiveStream.Close();
    }
}

/// <summary>
/// 提交POST方法至指定的Url,解析返回的数据
/// 参考地址:http://www.cnblogs.com/teikey/p/3373882.html
/// </summary>
/// <param name="url"></param>
/// <param name="requestParam"></param>
/// <param name="charset"></param>
/// <param name="contentType"></param>
/// <param name="dicHeader"></param>
/// <returns></returns>
[ShortDescription("根据Post方式请求URL下载数据")]
public static string WebMethodPostData(string url, string requestParam, string charset = "utf-8", string contentType = "application/x-www-form-urlencoded",Dictionary<string,string>dicHeader=null)
{
    WebRequest hr = null;
    WebResponse response = null;
    Stream receiveStreamIn = null;
    Stream receiveStreamOut = null;
    StreamReader srIn = null;
    StreamReader srOut = null;

    try
    {
        //创建访问对象
        hr = HttpWebRequest.Create(url);
        hr.Timeout = requestTimeOut;

        //拼接参数
        byte[] buf = System.Text.Encoding.GetEncoding(charset).GetBytes(requestParam);
        //hr.ContentType = "application/x-www-form-urlencoded";
        hr.ContentType = contentType;
        hr.ContentLength = buf.Length;
        hr.Method = "POST";

        if (dicHeader != null)
        {
            foreach (string sKey in dicHeader.Keys)
            {
                string sValue = dicHeader[sKey];

                hr.Headers.Add(sKey, sValue);
            }
        }

        System.IO.Stream RequestStream = hr.GetRequestStream();
        RequestStream.Write(buf, 0, buf.Length);
        RequestStream.Close();

        response = hr.GetResponse();
        receiveStreamIn = response.GetResponseStream();
        Encoding encode = Encoding.GetEncoding(charset);
        srIn = new StreamReader(receiveStreamIn, encode);
        char[] readbuffer = new char[2048];
        int n = srIn.Read(readbuffer, 0, 2048);

        string result = string.Empty;
        while (n > 0)
        {
            string str = new string(readbuffer, 0, n);
            result += str;
            n = srIn.Read(readbuffer, 0, 2048);
        }
        response.Close();   //注:此处用完以后立即关闭

        //如果未取得Json数据，则抛出异常
        if (string.IsNullOrEmpty(result)) throw new CustomApiException("消息长度：" + response.ContentLength + "消息内容：" + response.ToString(), url);

        return result;
    }
    catch (WebException ex)
    {
        string errorMessage = ex.Message;

        //需判断response是否==null
        response = ex.Response;
        if (response == null)
        {
            dynamic objErrorData = new { message = errorMessage, subErrors = "" };
            string jsonErrorData = JsonHelper.GetJsonByObject(objErrorData);

            throw new CustomApiJsonException(jsonErrorData, url + "?" + requestParam, ex);
        }
        else
        {
            receiveStreamOut = response.GetResponseStream();
            Encoding encode = Encoding.GetEncoding(charset);
            srOut = new StreamReader(receiveStreamOut, encode);
            char[] readbuffer = new char[2048];
            int n = srOut.Read(readbuffer, 0, 2048);

            string result = string.Empty;
            while (n > 0)
            {
                string str = new string(readbuffer, 0, n);
                result += str;
                n = srOut.Read(readbuffer, 0, 2048);
            }
            response.Close();

            //此处将错误信息和json信息同时返回
            dynamic objErrorData = new { message = errorMessage, subErrors = result };
            string jsonErrorData = JsonHelper.GetJsonByObject(objErrorData);

            throw new CustomApiJsonException(jsonErrorData, url + "?" + requestParam, ex);
        }
    }
    finally
    {
        //http://www.cnblogs.com/huangtailang/archive/2013/07/09/3180651.html
        if (hr != null) hr.Abort();//中止请求
        hr = null;  //需要写下Null

        if (response != null) response.Close();
        if (receiveStreamIn != null) receiveStreamIn.Close();
        if (receiveStreamOut != null) receiveStreamOut.Close();
        if (srIn != null) srIn.Close();
        if (srOut != null) srOut.Close();

        System.GC.Collect();//强制垃圾回收,并释放资源
    }
}

/// <summary>
/// 生成图片流的字符串参数值(目前用于速卖通图片上传)
/// </summary>
/// <param name="url"></param>
/// <param name="stream"></param>
/// <param name="contentType"></param>
/// <returns></returns>
[ShortDescription("根据Post方式请求URL下载数据")]
public static string WebMethodPostData(string url, Stream stream, string contentType)
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
    request.Timeout = requestTimeOut;
    try
    {
        request.Method = "POST";
        request.Accept = "*/*";
        request.KeepAlive = true;
        request.ContentType = contentType;
        request.Credentials = System.Net.CredentialCache.DefaultCredentials;
        request.ContentLength = stream.Length;

        using (Stream requestStream = request.GetRequestStream())
        {
            //将内存流数据读取位置归零
            stream.Position = 0;
            byte[] tempBuffer = new byte[stream.Length];
            stream.Read(tempBuffer, 0, tempBuffer.Length);
            stream.Close();

            //将内存流中的buffer写入到请求写入流
            requestStream.Write(tempBuffer, 0, tempBuffer.Length);
            requestStream.Close();

            //获取到上传请求的响应
            WebResponse response = request.GetResponse();

            //获取到上传返回的数据
            StreamReader reader = new StreamReader(response.GetResponseStream(), System.Text.Encoding.UTF8);
            string content = reader.ReadToEnd();
            response.Close();
            request = null;

            return content;
        }
    }
    finally
    {
        if (request != null) request.Abort();//中止请求
        request = null;  //需要写下Null

        System.GC.Collect();//强制垃圾回收,并释放资源
    }
}

public class WebClientEx : WebClient
{
    private int timeOut = 200;  //自定义读写超时设置(s)

    protected override WebRequest GetWebRequest(Uri address)
    {
        WebRequest request = base.GetWebRequest(address);
        request.Timeout = timeOut * 1000;

        return request;
    }
}

想要完整代码的小伙伴，可加小编微信：xiyang1011，免费领取

221102补充

1、JsonHelper.GetJsonByObject(objErrorData)，这个方法是引用Newtonsoft.Json这个类库，将Mode类转为Json的，一句代码就能搞定

2、CustomApiJsonException，这个类是基于Exception的创建的，直接改成这个就可以

3、所有代码加起来，其实就是完整的代码。哪里不清楚的，再加小编微信