看到过很多使用ConcurrentDictionary的建议，但没有可靠的例子，所以我将全身心投入到这个解决方案竞赛中。我不是一个线程安全的开发人员，所以如果这段代码不可靠，请为那些跟随的人说出来。

public static class XmlSerializerHelper
{
    private static readonly ConcurrentDictionary<Type, XmlSerializer> TypeSerializers = new ConcurrentDictionary<Type, XmlSerializer>();

    public static XmlSerializer GetSerializer(Type type)
    {
        return TypeSerializers.GetOrAdd(type,
        t =>
        {
            var importer = new XmlReflectionImporter();
            var mapping = importer.ImportTypeMapping(t, null, null);
            return new XmlSerializer(mapping);
        });
    }
}

我看过其他关于ConcurrentDictionary和Lazy加载值的文章。我不确定这是否与此相关，但这里是它的代码:

private static readonly ConcurrentDictionary<Type, Lazy<XmlSerializer>> TypeSerializers = new ConcurrentDictionary<Type, Lazy<XmlSerializer>>();

public static XmlSerializer GetSerializer(Type type)
{
    return TypeSerializers.GetOrAdd(type,
    t =>
    {
        var importer = new XmlReflectionImporter();
        var mapping = importer.ImportTypeMapping(t, null, null);
        var lazyResult = new Lazy<XmlSerializer>(() => new XmlSerializer(mapping), LazyThreadSafetyMode.ExecutionAndPublication);
        return lazyResult;
    }).Value;
}

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

我的解决方案是直接使用反射来创建序列化器。这就绕过了导致异常的奇怪文件加载。我将其打包在一个helper函数中，该函数还负责缓存序列化器。

private static readonly Dictionary<Type,XmlSerializer> _xmlSerializerCache = new Dictionary<Type, XmlSerializer>();

public static XmlSerializer CreateDefaultXmlSerializer(Type type) 
{
    XmlSerializer serializer;
    if (_xmlSerializerCache.TryGetValue(type, out serializer))
    {
        return serializer;
    }
    else
    {
        var importer = new XmlReflectionImporter();
        var mapping = importer.ImportTypeMapping(type, null, null);
        serializer = new XmlSerializer(mapping);
        return _xmlSerializerCache[type] = serializer;
    }
}

在我的一个。net标准dll中也有类似的问题。

我使用了Microsoft.XmlSerializer.Generator nuget，它可以在. net Core和. net Standard上预生成XmlSerializer。

Like Martin Sherburn said, this is normal behavior. The constructor of the XmlSerializer first tries to find an assembly named [YourAssembly].XmlSerializers.dll which should contain the generated class for serialization of your type. Since such a DLL has not been generated yet (they are not by default), a FileNotFoundException is thrown. When that happenes, XmlSerializer's constructor catches that exception, and the DLL is generated automatically at runtime by the XmlSerializer's constructor (this is done by generating C# source files in the %temp% directory of your computer, then compiling them using the C# compiler). Additional constructions of an XmlSerializer for the same type will just use the already generated DLL.

更新:从。net 4.5开始，XmlSerializer不再执行代码生成，也不再为了在运行时创建序列化程序集而使用c#编译器执行编译，除非通过设置配置文件设置(useLegacySerializerGeneration)显式强制执行。此更改消除了对csc.exe的依赖，并提高了启动性能。来源:. net Framework 4.5 Readme，章节1.3.8.1。

异常由XmlSerializer的构造函数处理。你不需要自己做任何事情，你可以点击“继续”(F5)继续执行你的程序，一切都会好的。如果你被异常停止程序执行并弹出异常助手所困扰，你要么关闭“只是我的代码”，要么将FileNotFoundException设置为在抛出时中断执行，而不是在“User-unhandled”时。

打开“Just My Code”，请转到“Tools >> Options >> Debugging >> General >> enable Just My Code”。要关闭FileNotFound被抛出时的执行中断，请转到调试>>异常>>找到>>输入'FileNotFoundException' >>取消System.IO.FileNotFoundException中的' thrown '复选框。

我也遇到了类似的问题，忽略这个异常对我不起作用。我的代码调用NServiceBus的配置configuration . with(…).XmlSerializer()…

对我来说，解决这个问题的方法是改变我项目的平台。

去构建\配置管理器… 找到你的项目并更改平台(在我的情况下，从x86到任何CPU)