{"Message":"Exception message","StackTrace":" at WebApplication.HelloService.HelloWorld() in C:\Projects\Stackoverflow Examples\WebApplication\WebApplication\HelloService.asmx.cs:line 22","ExceptionType":"System.ApplicationException"}
- 当打开自定义错误时，Web服务向客户端返回默认消息，并删除堆栈跟踪和异常类型：{"Message":"There was an error processing the request.","StackTrace":"","ExceptionType":""}
因此，我们需要关闭Web服务的自定义错误，并插入一个HTTP模块，它可以：using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Web;
public class ErrorHandlerModule : IHttpModule {
public void Init(HttpApplication context) {
context.PostRequestHandlerExecute += OnPostRequestHandlerExecute;
context.EndRequest += OnEndRequest;
}
static void OnPostRequestHandlerExecute(object sender, EventArgs e) {
HttpApplication context = (HttpApplication) sender;
// TODO: Update with the correct check for your application
if (context.Request.Path.StartsWith("/HelloService.asmx")
&& context.Response.StatusCode == 500) {
context.Response.Filter =
new ErrorHandlerFilter(context.Response.Filter);
context.EndRequest += OnEndRequest;
}
}
static void OnEndRequest(object sender, EventArgs e) {
HttpApplication context = (HttpApplication) sender;
ErrorHandlerFilter errorHandlerFilter =
context.Response.Filter as ErrorHandlerFilter;
if (errorHandlerFilter == null) {
return;
}
string originalContent =
Encoding.UTF8.GetString(
errorHandlerFilter.OriginalBytesWritten.ToArray());
// If customErrors are Off then originalContent will contain JSON with
// the original exception message, stack trace and exception type.
// TODO: log the exception
}
public void Dispose() { }
}这个模块使用以下过滤器来覆盖发送给客户端的内容并存储原始字节（其中包括异常消息、堆栈跟踪和异常类型）：
public class ErrorHandlerFilter : Stream {
private readonly Stream _responseFilter;
public List OriginalBytesWritten { get; private set; }
private const string Content =
"{\"Message\":\"There was an error processing the request.\"" +
",\"StackTrace\":\"\",\"ExceptionType\":\"\"}";
public ErrorHandlerFilter(Stream responseFilter) {
_responseFilter = responseFilter;
OriginalBytesWritten = new List();
}
public override void Flush() {
byte[] bytes = Encoding.UTF8.GetBytes(Content);
_responseFilter.Write(bytes, 0, bytes.Length);
_responseFilter.Flush();
}
public override long Seek(long offset, SeekOrigin origin) {
return _responseFilter.Seek(offset, origin);
}
public override void SetLength(long value) {
_responseFilter.SetLength(value);
}
public override int Read(byte[] buffer, int offset, int count) {
return _responseFilter.Read(buffer, offset, count);
}
public override void Write(byte[] buffer, int offset, int count) {
for (int i = offset; i < offset + count; i++) {
OriginalBytesWritten.Add(buffer[i]);
}
}
public override bool CanRead {
get { return _responseFilter.CanRead; }
}
public override bool CanSeek {
get { return _responseFilter.CanSeek; }
}
public override bool CanWrite {
get { return _responseFilter.CanWrite; }
}
public override long Length {
get { return _responseFilter.Length; }
}
public override long Position {
get { return _responseFilter.Position; }
set { _responseFilter.Position = value; }
}
}使用这种方法需要关闭Web服务的自定义错误。您可能希望在应用程序的其余部分保持自定义错误打开，因此Web服务应该放置在子目录中。可以使用覆盖父设置的web.config仅在该目录中关闭自定义错误。
您在后台运行存储过程。然后，对于一个单变量，它返回了多个值。由此产生了冲突，并且抛出了这个错误。
我知道这并不完全回答了问题，但我曾经自己去寻找过这个答案，最终却一无所获。最后只好在每个 Web 服务调用中加入 try/catch，并在 catch 中调用我们的错误日志记录器。虽然有些麻烦，但至少能够解决问题。