.NET HttpWebRequest、WebClient、HttpClient
HttpWebRequest:
继承 WebRequest
命名空间: System.Net,这是.NET创建者最初开发用于使用HTTP请求的标准类。使用HttpWebRequest可以让开发者控制请求/响应流程的各个方面,如 timeouts, cookies, headers, protocols。另一个好处是HttpWebRequest类不会阻塞UI线程。例如,当您从响应很慢的API服务器下载大文件时,您的应用程序的UI不会停止响应。HttpWebRequest通常和WebResponse一起使用,一个发送请求,一个获取数据。HttpWebRquest更为底层一些,能够对整个访问过程有个直观的认识,但同时也更加复杂一些。
//POST方法
public static string HttpPost(string Url, string postDataStr)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
request.Method = “POST”;
request.ContentType = “application/x-www-form-urlencoded”;
Encoding encoding = Encoding.UTF8;
byte[] postData = encoding.GetBytes(postDataStr);
request.ContentLength = postData.Length;
Stream myRequestStream = request.GetRequestStream();
myRequestStream.Write(postData, 0, postData.Length);
myRequestStream.Close();
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream myResponseStream = response.GetResponseStream();
StreamReader myStreamReader = new StreamReader(myResponseStream, encoding);
string retString = myStreamReader.ReadToEnd();
myStreamReader.Close();
myResponseStream.Close();
return retString;
}
//GET方法
public static string HttpGet(string Url, string postDataStr)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url + (postDataStr == “” ? “” : “?”) + postDataStr);
request.Method = “GET”;
request.ContentType = “text/html;charset=UTF-8”;
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream myResponseStream = response.GetResponseStream();
StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding(“utf-8”));
string retString = myStreamReader.ReadToEnd();
myStreamReader.Close();
myResponseStream.Close();
return retString;
}
WebClient:
public abstract class WebRequest : MarshalByRefObject, ISerializable
public class HttpWebRequest : WebRequest, ISerializable
public class WebClient : Component
命名空间System.Net,WebClient是一种更高级别的抽象,是HttpWebRequest为了简化最常见任务而创建的,使用过程中你会发现他缺少基本的header,timeoust的设置,不过这些可以通过继承httpwebrequest来实现。相对来说,WebClient比WebRequest更加简单,它相当于封装了request和response方法,不过需要说明的是,**Webclient和WebRequest继承的是不同类,两者在继承上没有任何关系。**使用WebClient可能比HttpWebRequest直接使用更慢(大约几毫秒),但却更为简单,减少了很多细节,代码量也比较少。
public class WebClientHelper
{
public static string DownloadString(string url)
{
WebClient wc = new WebClient();
//wc.BaseAddress = url; //设置根目录
wc.Encoding = Encoding.UTF8; //设置按照何种编码访问,如果不加此行,获取到的字符串中文将是乱码
string str = wc.DownloadString(url);
return str;
}
public static string DownloadStreamString(string url)
{
WebClient wc = new WebClient();
wc.Headers.Add(“User-Agent”, “Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36”);
Stream objStream = wc.OpenRead(url);
StreamReader _read = new StreamReader(objStream, Encoding.UTF8); //新建一个读取流,用指定的编码读取,此处是utf-8
string str = _read.ReadToEnd();
objStream.Close();
_read.Close();
return str;
}
public static void DownloadFile(string url, string filename)
{
WebClient wc = new WebClient();
wc.DownloadFile(url, filename); //下载文件
}
public static void DownloadData(string url, string filename)
{
WebClient wc = new WebClient();
byte [] bytes = wc.DownloadData(url); //下载到字节数组
FileStream fs = new FileStream(filename, FileMode.Create);
fs.Write(bytes, 0, bytes.Length);
fs.Flush();
fs.Close();
}
public static void DownloadFileAsync(string url, string filename)
{
WebClient wc = new WebClient();
wc.DownloadFileCompleted += DownCompletedEventHandler;
wc.DownloadFileAsync(new Uri(url), filename);
Console.WriteLine("下载中。。。");
}
private static void DownCompletedEventHandler(object sender, AsyncCompletedEventArgs e)
{
Console.WriteLine(sender.ToString()); //触发事件的对象
Console.WriteLine(e.UserState);
Console.WriteLine(e.Cancelled);
Console.WriteLine("异步下载完成!");
}
public static void DownloadFileAsync2(string url, string filename)
{
WebClient wc = new WebClient();
wc.DownloadFileCompleted += (sender, e) =>
{
Console.WriteLine("下载完成!");
Console.WriteLine(sender.ToString());
Console.WriteLine(e.UserState);
Console.WriteLine(e.Cancelled);
};
wc.DownloadFileAsync(new Uri(url), filename);
Console.WriteLine("下载中。。。");
}
}
HttpClient:
public class HttpClient : HttpMessageInvoker
HttpClient是.NET4.5引入的一个HTTP客户端库,其命名空间为 System.Net.Http ,.NET 4.5之前我们可能使用WebClient和HttpWebRequest来达到相同目的。HttpClient利用了最新的面向任务模式,使得处理异步请求非常容易。它适合用于多次请求操作,一般设置好默认头部后,可以进行重复多次的请求,基本上用一个实例可以提交任何的HTTP请求。HttpClient有预热机制,第一次进行访问时比较慢,所以不应该用到HttpClient就new一个出来,应该使用单例或其他方式获取HttpClient的实例
static void Main(string[] args)
{
const string GetUrl = “http://xxxxxxx/api/UserInfo/GetUserInfos”;//查询用户列表的接口,Get方式访问
const string PostUrl = “http://xxxxxxx/api/UserInfo/AddUserInfo”;//添加用户的接口,Post方式访问
//使用Get请求
GetFunc(GetUrl);
UserInfo user = new UserInfo { Name = "jack", Age = 23 };
string userStr = JsonHelper.SerializeObject(user);//序列化
//使用Post请求
PostFunc(PostUrl, userStr);
Console.ReadLine();
}
/// <summary>
/// Get请求
/// </summary>
/// <param name="path"></param>
static async void GetFunc(string path)
{
//消息处理程序
HttpClientHandler handler = new HttpClientHandler() { AutomaticDecompression = DecompressionMethods.GZip };
HttpClient httpClient = new HttpClient();
//异步get请求
HttpResponseMessage response = await httpClient.GetAsync(path);
//确保响应正常,如果响应不正常EnsureSuccessStatusCode()方法会抛出异常
response.EnsureSuccessStatusCode();
//异步读取数据,格式为String
string resultStr = await response.Content.ReadAsStringAsync();
Console.WriteLine(resultStr);
}
/// <summary>
/// Post请求
/// </summary>
/// <param name="path"></param>
/// <param name="data"></param>
static async void PostFunc(string path, string data)
{
HttpClientHandler handler = new HttpClientHandler() { AutomaticDecompression = DecompressionMethods.GZip };
HttpClient httpClient = new HttpClient(handler);
//HttpContent是HTTP实体正文和内容标头的基类。
HttpContent httpContent = new StringContent(data, Encoding.UTF8, "text/json");
//httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("BasicAuth", Ticket);//验证请求头赋值
//httpContent.Headers.Add(string name,string value) //添加自定义请求头
//发送异步Post请求
HttpResponseMessage response = await httpClient.PostAsync(path, httpContent);
response.EnsureSuccessStatusCode();
string resultStr = await response.Content.ReadAsStringAsync();
Console.WriteLine(resultStr);
}
}
注意:因为HttpClient有预热机制,第一次进行访问时比较慢,所以我们最好不要用到HttpClient就new一个出来,应该使用单例或其他方式获取HttpClient的实例