我一直在使用的一个应用程序在尝试序列化类型时失败了。

像这样的陈述

XmlSerializer lizer = new XmlSerializer(typeof(MyType));

生产:

System.IO.FileNotFoundException occurred
  Message="Could not load file or assembly '[Containing Assembly of MyType].XmlSerializers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified."
  Source="mscorlib"
  FileName="[Containing Assembly of MyType].XmlSerializers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"
  FusionLog=""
  StackTrace:
       at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection)
       at System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection)

我没有为我的类定义任何特殊的序列化器。

我该如何解决这个问题?


当前回答

另一方面,对编译错误进行故障排除是非常复杂的。这些问题在FileNotFoundException异常中显示,并显示如下信息:

File or assembly name abcdef.dll, or one of its dependencies, was not found. File name: "abcdef.dll"
   at System.Reflection.Assembly.nLoad( ... )
   at System.Reflection.Assembly.InternalLoad( ... )
   at System.Reflection.Assembly.Load(...)
   at System.CodeDom.Compiler.CompilerResults.get_CompiledAssembly() 

You may wonder what a file not found exception has to do with instantiating a serializer object, but remember: the constructor writes C# files and tries to compile them. The call stack of this exception provides some good information to support that suspicion. The exception occurred while the XmlSerializer attempted to load an assembly generated by CodeDOM calling the System.Reflection.Assembly.Load method. The exception does not provide an explanation as to why the assembly that the XmlSerializer was supposed to create was not present. In general, the assembly is not present because the compilation failed, which may happen because, under rare circumstances, the serialization attributes produce code that the C# compiler fails to compile.

请注意 当XmlSerializer在不能访问临时目录的帐户或安全环境下运行时,也会发生此错误。

来源: http://msdn.microsoft.com/en-us/library/aa302290.aspx

其他回答

信不信由你,这是正常行为。抛出一个异常,但由XmlSerializer处理,因此如果忽略它,一切都应该继续正常进行。

我发现这非常烦人,如果你搜索一下,会有很多抱怨,但据我所知,微软并不打算对此采取任何措施。

如果关闭特定异常的第一次机会异常,就可以避免在调试时一直弹出异常。在Visual Studio中,打开调试->异常(或按Ctrl + Alt + E),公共语言运行时异常->系统。IO -> System.IO.FileNotFoundException。

您可以在博客文章c# XmlSerializer FileNotFound异常(其中讨论了Chris Sells的工具XmlSerializerPreCompiler)中找到关于另一种方法的信息。

另一方面,对编译错误进行故障排除是非常复杂的。这些问题在FileNotFoundException异常中显示,并显示如下信息:

File or assembly name abcdef.dll, or one of its dependencies, was not found. File name: "abcdef.dll"
   at System.Reflection.Assembly.nLoad( ... )
   at System.Reflection.Assembly.InternalLoad( ... )
   at System.Reflection.Assembly.Load(...)
   at System.CodeDom.Compiler.CompilerResults.get_CompiledAssembly() 

You may wonder what a file not found exception has to do with instantiating a serializer object, but remember: the constructor writes C# files and tries to compile them. The call stack of this exception provides some good information to support that suspicion. The exception occurred while the XmlSerializer attempted to load an assembly generated by CodeDOM calling the System.Reflection.Assembly.Load method. The exception does not provide an explanation as to why the assembly that the XmlSerializer was supposed to create was not present. In general, the assembly is not present because the compilation failed, which may happen because, under rare circumstances, the serialization attributes produce code that the C# compiler fails to compile.

请注意 当XmlSerializer在不能访问临时目录的帐户或安全环境下运行时,也会发生此错误。

来源: http://msdn.microsoft.com/en-us/library/aa302290.aspx

只是作为参考。从D-B的回答和评论中,我得出了这个接近D-B的解决方案。它在我的所有情况下都工作得很好,并且是线程安全的。我不认为使用ConcurrentDictionary是可以的。

using System;
using System.Collections.Generic;
using System.Xml.Serialization;

namespace HQ.Util.General
{
    public class XmlSerializerHelper
    {
        private static readonly Dictionary<Type, XmlSerializer> _dictTypeToSerializer = new Dictionary<Type, XmlSerializer>();

        public static XmlSerializer GetSerializer(Type type)
        {
            lock (_dictTypeToSerializer)
            {
                XmlSerializer serializer;
                if (! _dictTypeToSerializer.TryGetValue(type, out serializer))
                {
                    var importer = new XmlReflectionImporter();
                    var mapping = importer.ImportTypeMapping(type, null, null);
                    serializer = new XmlSerializer(mapping);
                    return _dictTypeToSerializer[type] = serializer;
                }

                return serializer;
            }
        }
    }
}

用法:

        if (File.Exists(Path))
        {
            using (XmlTextReader reader = new XmlTextReader(Path))
            {
                // XmlSerializer x  = new XmlSerializer(typeof(T));
                var x = XmlSerializerHelper.GetSerializer(typeof(T));

                try
                {
                    options = (OptionsBase<T>)x.Deserialize(reader);
                }
                catch (Exception ex)
                {
                    Log.Instance.AddEntry(LogType.LogException, "Unable to open Options file: " + Path, ex);
                }
            }
        }

Martin Sheburn最初的回答是正确的。 来自edeboursetty, tomas-kubes)的代码示例,quadfinity应该解决在调试器中不引发过量异常的问题。

这里有一个简短的解决方案:

internal sealed static class XmlSerializerHelper
{
    private static readonly ConcurrentDictionary<Type, System.Xml.Serialization.XmlSerializer> s_xmlSerializers = new();

    public static System.Xml.Serialization.XmlSerializer Get<T>()
    {
        return s_xmlSerializers.GetOrAdd(typeof(T), _ => System.Xml.Serialization.XmlSerializer.FromTypes(new [] {typeof(T)})[0]);
    }
}

XmlSerializer函数。FromTypes不会抛出异常,但它会泄漏内存。这就是为什么你需要为每个类型缓存这样的序列化器,以避免内存泄漏为每个创建的实例。

创建自己的XmlSerializer工厂并简单地使用它:

XmlSerializer serializer = XmlSerializerFactoryNoThrow.Create(typeof(MyType));

工厂是这样的:

public static class XmlSerializerFactoryNoThrow
{
    public static Dictionary<Type, XmlSerializer> _cache = new Dictionary<Type, XmlSerializer>();

    private static object SyncRootCache = new object();        

    /// <summary>
    /// //the constructor XmlSerializer.FromTypes does not throw exception, but it is said that it causes memory leaks
    /// http://stackoverflow.com/questions/1127431/xmlserializer-giving-filenotfoundexception-at-constructor
    /// That is why I use dictionary to cache the serializers my self.
    /// </summary>
    public static XmlSerializer Create(Type type)
    {
        XmlSerializer serializer;

        lock (SyncRootCache)
        {
            if (_cache.TryGetValue(type, out serializer))
                return serializer;
        }

        lock (type) //multiple variable of type of one type is same instance
        {
            //constructor XmlSerializer.FromTypes does not throw the first chance exception           
            serializer = XmlSerializer.FromTypes(new[] { type })[0];
            //serializer = XmlSerializerFactoryNoThrow.Create(type);
        }

        lock (SyncRootCache)
        {
            _cache[type] = serializer;
        }
        return serializer;
    }       
}

更复杂的版本,没有内存泄漏的可能性(请有人检查代码):

    public static XmlSerializer Create(Type type)
    {
        XmlSerializer serializer;

        lock (SyncRootCache)
        {
            if (_cache.TryGetValue(type, out serializer))
                return serializer;
        }

        lock (type) //multiple variable of type of one type is same instance
        {
            lock (SyncRootCache)
            {
                if (_cache.TryGetValue(type, out serializer))
                    return serializer;
            }
            serializer = XmlSerializer.FromTypes(new[] { type })[0];
            lock (SyncRootCache)
            {
                _cache[type] = serializer;
            }
        }          
        return serializer;
    }       
}