出现的环境.Net4.0 + WebApi1(4.0.30506.0) + Microsoft.Bcl.Async.1.0.168
自己死活看不出原因, 分享出来给大家看看,希望有人能找到问题的关键
出现错误的是下面这两个模块
下面的CorsMessageHandler,抄的http://www.cnblogs.com/artech/p/cors-4-asp-net-web-api-04.html, 做了部分修改
1 public class CorsMessageHandler : DelegatingHandler
2 {
3 private static readonly CorsAttribute DEFAULT_CORS = new CorsAttribute("*");//默认支持所有
4
5 protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
6 {
7 cancellationToken.ThrowIfCancellationRequested();
8 try
9 {
10 //得到描述目标Action的HttpActionDescriptor
11 HttpMethod originalMethod = request.Method;
12 bool isPreflightRequest = request.IsPreflightRequest();
13 if (isPreflightRequest)
14 {
15 string method = request.Headers.GetValues("Access-Control-Request-Method").First();
16 request.Method = new HttpMethod(method);
17 }
18 HttpConfiguration configuration = request.GetConfiguration();
19 HttpControllerDescriptor controllerDescriptor = configuration.Services.GetHttpControllerSelector().SelectController(request);
20 HttpControllerContext controllerContext = new HttpControllerContext(request.GetConfiguration(), request.GetRouteData(), request)
21 {
22 ControllerDescriptor = controllerDescriptor
23 };
24 //避免权限错误
25 //HttpActionDescriptor actionDescriptor = configuration.Services.GetActionSelector().SelectAction(controllerContext);
26
27 //根据HttpActionDescriptor得到应用的CorsAttribute特性
28 CorsAttribute corsAttribute = null;
29 //corsAttribute = actionDescriptor.GetCustomAttributes<CorsAttribute>().FirstOrDefault();
30 corsAttribute = corsAttribute?? controllerDescriptor.GetCustomAttributes<CorsAttribute>().FirstOrDefault();
31 if (null == corsAttribute)
32 {
33 corsAttribute = DEFAULT_CORS;
34 //return base.SendAsync(request, cancellationToken);
35 }
36
37 //利用CorsAttribute实施授权并生成响应报头
38 IDictionary<string, string> headers;
39 request.Method = originalMethod;
40 bool authorized = corsAttribute.TryEvaluate(request, out headers);
41 HttpResponseMessage response;
42 if (isPreflightRequest)
43 {
44 if (authorized)
45 {
46 response = new HttpResponseMessage(HttpStatusCode.OK);
47 }
48 else
49 {
50 response = request.CreateErrorResponse(HttpStatusCode.BadRequest, corsAttribute.ErrorMessage);
51 }
52 }
53 else
54 {
55 var tmp = base.SendAsync(request, cancellationToken);
56 tmp.Wait();
57 response = tmp.Result;
58 }
59
60 if (headers != null)
61 {
62 foreach (var item in headers)
63 {
64 response.Headers.Add(item.Key, item.Value);
65 }
66 }
67 return response;
68 }
69 catch
70 {
71 }
72 //catch -> fallback
73 return await base.SendAsync(request, cancellationToken);
74 }
75 }
76 [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
77 public class CorsAttribute : Attribute
78 {
79 public Uri[] AllowOrigins { get; private set; }
80 public string ErrorMessage { get; private set; }
81
82 public CorsAttribute(params string[] allowOrigins)
83 {
84 var tmp = (allowOrigins ?? new string[0]);
85 if (tmp.Length == 1 && "*" == tmp[0])
86 {
87 this.AllowOrigins = null;
88 }
89 else
90 {
91 this.AllowOrigins = tmp.Select(origin => new Uri(origin)).ToArray();
92 }
93 }
94
95 public bool TryEvaluate(HttpRequestMessage request, out IDictionary<string, string> headers)
96 {
97 headers = null;
98
99 //bugfix: GetValues在找不到时会报错
100 IEnumerable<string> origins;
101 if (request.Headers.TryGetValues("Origin", out origins))
102 {
103 string origin = origins.FirstOrDefault();
104 if (!String.IsNullOrEmpty(origin))
105 {
106 Uri originUri = new Uri(origin);
107 if (this.AllowOrigins == null || this.AllowOrigins.Contains(originUri))//支持"*"
108 {
109 headers = this.GenerateResponseHeaders(request);
110 return true;
111 }
112 }
113 }
114 this.ErrorMessage = "Cross-origin request denied";
115 return false;
116 }
117
118 private IDictionary<string, string> GenerateResponseHeaders(HttpRequestMessage request)
119 {
120 //设置响应报头"Access-Control-Allow-Methods"
121 string origin = request.Headers.GetValues("Origin").First();
122 Dictionary<string, string> headers = new Dictionary<string, string>();
123 headers.Add("Access-Control-Allow-Origin", origin);
124 if (request.IsPreflightRequest())
125 {
126 //设置响应报头"Access-Control-Request-Headers"
127 //和"Access-Control-Allow-Headers"
128 string requestHeaders = request.Headers.GetValues("Access-Control-Request-Headers").FirstOrDefault();
129 if (!string.IsNullOrEmpty(requestHeaders))
130 {
131 headers.Add("Access-Control-Allow-Headers", requestHeaders);
132 }
133 //string requestMethods = request.Headers.GetValues("Access-Control-Request-Method").FirstOrDefault();
134 //if (!string.IsNullOrEmpty(requestHeaders))
135 //{
136 // headers.Add("Access-Control-Allow-Methods", requestMethods + ", OPTIONS");
137 //}
138 //else
139 //{
140 headers.Add("Access-Control-Allow-Methods", "*");
141 //}
142 }
143 headers.Add("Access-Control-Allow-Credentials", "true");//true, 允许跨域传cookie, 要在POST的返回值中也存在
144 return headers;
145 }
146 }
一个简单的异常过滤器
1 public class JsonExceptionFilter : FilterAttribute, IExceptionFilter//, IActionFilter
2 {
3
4 public Task ExecuteExceptionFilterAsync(HttpActionExecutedContext actionExecutedContext, CancellationToken cancellationToken)
5 {
6 return Task.Factory.StartNew((obj) =>
7 {
8 CancellationToken ct = (CancellationToken)obj;
9 if (actionExecutedContext.Exception != null)
10 {
11 var res = new ResultModel<String>(false, actionExecutedContext.Exception.GetType().ToString());
12 var resText = JsonConvert.SerializeObject(res);
13 if (actionExecutedContext.Response == null)
14 {
15 actionExecutedContext.Response = new HttpResponseMessage();
16 }
17 actionExecutedContext.Response.Content = new StringContent("{\"State\":-255}", Encoding.UTF8, "application/json");
18 }
19 }, cancellationToken, cancellationToken);
20 }
21 }
现在存在的问题是如果Action内部有异常被过滤器捕获, CorsMessageHandler就卡死在
var tmp = base.SendAsync(request, cancellationToken); response = tmp.Result;//卡死在这里, 用tmp.Wait();也是一样卡死
调试看task的State是WaitingForActivation, 但是用Wait/Result无限期卡死无法得到结果, 但是用await(Microsoft.Bcl.Async引入)就不存在问题, 能正常执行出结果
时间： 2024-10-13 23:49:38