ASP.NET for WebApi
WebApi,听说过吧?呵呵。
感觉比WebService,WCF要强。尤其是那个啥WCF,啥鬼东西,真难懂。真难搞。真难用。
说比WebService要强,是因为不用在本地先生成个代理。而且XML也显得过于庞大。
用ASP.NET 编写 WebApi 的话,跟MVC差不多。生成的项目也有控制器,视图之类。只不过,其控制器继承的是ApiController。
还有一个不同的是,是不用写action的,只有controller。当然,你硬是要写也可以。但根据RESTful原则,WebApi提供的API方法名称应该纯粹是名词,而没有动词,系统根据请求方式来判断请求者意图,并执行相应操作。什么意思呢?
比如一个API 地址为
http://192.168.0.1/api/book/108
相应的方法为
public class BookController : ApiController
{
public string Get(string id)
{//读取book信息
return "Get " + id;
}
public string Post([FromBody]object obj)
{//新增book
return "Post";
}
public string Put(int id,[FromBody]object obj)
{//修改book
return "Put " + id;
}
public string Delete(string id)
{//删除book
return "Delete " + id;
}
}
当请求方式为GET时,执行的是方法Get(),Post时,执行的是方法Post()。API地址就一个:
http://192.168.0.1/api/book/108
108是ID值。
而不必写成下面那么傻:
http://192.168.0.1/api/GetBook/108
http://192.168.0.1/api/DeleteBook/108
当然,RESTful原则是这么推荐,但现实往往比较骨感。因为许多网络环境并不支持PUT和DELETE的请求方式,只支持GET和POST。怪不得我调试的时候,GET和POST都可以,到了PUT和DELETE,都报405错误:方法不被允许。错误代码为4开头,说明是浏览器不支持。
幸而看了蒋金楠博客。解决方案如下:
//我们定义了如下一个HttpMethodOverrideHandler类型,它继承自DelegatingHandler。我们在重写的SendAsync方法中实现了对“X-HTTP-Method-Override”报头的提取和对HTTP方法的重写,最后调用基类的同名方法将处理后的请求传递给后续的HttpMessageHandler。
public class HttpMethodOverrideHandler : DelegatingHandler
{
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
IEnumerable<string> methodOverrideHeader;
if (request.Headers.TryGetValues("X-HTTP-Method-Override", out methodOverrideHeader))
{
request.Method = new HttpMethod(methodOverrideHeader.First());
}
return base.SendAsync(request, cancellationToken);
}
}
在api项目的global.asax.cs里调用这个类:
public class WebApiApplication : System.Web.HttpApplication
{
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
GlobalConfiguration.Configure(WebApiConfig.Register);
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
//调用基类的同名方法将处理后的请求传递给后续的HttpMessageHandler。
GlobalConfiguration.Configuration.MessageHandlers.Add(new HttpMethodOverrideHandler());
}
}
这样,请求过来时,读取这些额外设置的报头,系统就能知道请求者的意图了。
前端调用方式如下:
<script type="text/javascript">
(function(){
$.ajax({
type: 'POST',//明地里用支持的HTTP请求方式
url: 'http://192.168.0.1/api/GetBook/108',
data: '{"name":"王小波文集"}',
contentType: "application/json; charset=utf-8",
dataType: 'json',
beforeSend: function (xhr) {
//暗地里写入额外的报头信息
xhr.setRequestHeader('X-HTTP-Method-Override', 'PUT');
},
success: function (results) {
alert(results);
},
error: function (ex) {
alert("错误:" + ex.statusText);
}
})
})();
</script>
服务器端请求也可以,看俺的单元测试代码:
[TestClass()]
public class InterfaceControllerTests
{
string _baseurl = "http://192.168.0.1/api/GetBook/108";
public InterfaceControllerTests()
{
}
[TestMethod()]
public void GetTest()
{
string url = _baseurl + "/1";
string re;
using (WebClient webClient = new WebClient())
{
webClient.Encoding = Encoding.GetEncoding("utf-8");
webClient.Headers.Add("Content-Type", "application/x-www-form-urlencoded");//采取POST方式必须加的header,如果改为GET方式的话就去掉这句话即可
re = webClient.DownloadString(url);
}
Assert.AreEqual("\"Get 1\"", re);
}
[TestMethod()]
public void PostTest()
{
string url = _baseurl;
string postString = @"{""id"":108}";//这里即为传递的参数,可以用工具抓包分析,也可以自己分析,主要是form里面每一个name都要加进来
byte[] postData = Encoding.UTF8.GetBytes(postString);//编码,尤其是汉字,事先要看下抓取网页的编码方式
string re;
using (WebClient webClient = new WebClient())
{
webClient.Encoding = Encoding.GetEncoding("utf-8");
webClient.Headers.Add("Content-Type", "application/json");//采取POST方式必须加的header,如果改为GET方式的话就去掉这句话即可
byte[] responseData = webClient.UploadData(url, "POST", postData);//得到返回字符流
re = Encoding.UTF8.GetString(responseData);//解码
}
Assert.AreNotEqual(-1, re.IndexOf("Post"));
}
[TestMethod()]
public void PutTest()
{
string url = _baseurl + "/109";
string postString = @"{""id"":109}";
byte[] postData = Encoding.UTF8.GetBytes(postString);
string re;
using (WebClient webClient = new WebClient())
{
webClient.Encoding = Encoding.GetEncoding("utf-8");
webClient.Headers.Add("Content-Type", "application/json");
webClient.Headers.Add("X-HTTP-Method-Override", "PUT");
byte[] responseData = webClient.UploadData(url, "POST", postData);
re = Encoding.UTF8.GetString(responseData);
}
Assert.AreNotEqual(-1, re.IndexOf("Put"));
}
[TestMethod()]
public void DeleteTest()
{
string url = _baseurl + "/1";
string re;
using (WebClient webClient = new WebClient())
{
webClient.Encoding = Encoding.GetEncoding("utf-8");
webClient.Headers.Add("Content-Type", "application/x-www-form-urlencoded");
webClient.Headers.Add("X-HTTP-Method-Override", "DELETE");
re = webClient.DownloadString(url);
}
Assert.AreNotEqual(-1, re.IndexOf("Delete"));
}
}