Xamarin Android-链接器和ServiceStack.Text

Question

我很难让应用程序使用完全链接。这是我的设置(我的程序集名称已更改(：

• 适用于Android的Mono 4.4.54
• 安卓应用程序(MyApp(
• 平台无关库(MyLib(

我正在尝试使用ServiceStack.text从JSON文本反序列化一个类型(Person(。它在仅链接SDK程序集时工作良好。

我不是在MyLib中放置链接器包含属性，而是在MyApp使用LinkDescriptionXML文件。它看起来像这样：

<?xml version="1.0" encoding="utf-8" ?>
<linker>
  <assembly fullname="MyLib">
    <type fullname="MyLib.Person" preserve="fields">
      <method name=".ctor" />
    </type>
  </assembly>
</linker>

这是我的logcat输出：

E/MyApp(14494): InitialiseUser(): System.TypeInitializationException: An exception was thrown by the type initializer for ServiceStack.Text.Json.JsonReader`1 ---> System.ArgumentNullException: Argument cannot be null.
E/MyApp(14494): Parameter name: method
E/MyApp(14494):   at System.Delegate.CreateDelegate (System.Type type, System.Object firstArgument, System.Reflection.MethodInfo method, Boolean throwOnBindFailure, Boolean allowClosed) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at System.Delegate.CreateDelegate (System.Type type, System.Reflection.MethodInfo method, Boolean throwOnBindFailure) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at ServiceStack.Text.PlatformExtensions.MakeDelegate (System.Reflection.MethodInfo mi, System.Type delegateType, Boolean throwOnBindFailure) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at ServiceStack.Text.Json.JsonReader.GetParseFn (System.Type type) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at ServiceStack.Text.Json.JsonTypeSerializer.GetParseFn (System.Type type) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at ServiceStack.Text.Common.TypeAccessor.Create (ITypeSerializer serializer, ServiceStack.Text.TypeConfig typeConfig, System.Reflection.PropertyInfo propertyInfo) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at ServiceStack.Text.Common.DeserializeTypeRef.GetTypeAccessorMap (ServiceStack.Text.TypeConfig typeConfig, ITypeSerializer serializer) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at ServiceStack.Text.Common.DeserializeType`1[ServiceStack.Text.Json.JsonTypeSerializer].GetParseMethod (ServiceStack.Text.TypeConfig typeConfig) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at ServiceStack.Text.Common.JsReader`1[ServiceStack.Text.Json.JsonTypeSerializer].GetCoreParseFn[Person] () [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at ServiceStack.Text.Common.JsReader`1[ServiceStack.Text.Json.JsonTypeSerializer].GetParseFn[Person] () [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at ServiceStack.Text.Json.JsonReader`1[MyLib.Person]..cctor () [0x00000] in <filename unknown>:0 
E/MyApp(14494):   --- End of inner exception stack trace ---
E/MyApp(14494):   at ServiceStack.Text.JsonSerializer.DeserializeFromString[Person] (System.String value) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at MyLib.Person.FromJson (System.String json, Boolean throwOnNullOrEmpty) [0x00000] in <filename unknown>:0 
E/MyApp(14494):   at MyApp.MainActivity.InitialiseUser () [0x00000] in <filename unknown>:0 

在此之后，我的Person实例为null。

从输出中似乎找不到Person的默认构造函数(它没有显式定义的构造函数(。

非常感谢您的帮助。

Answer 1

实际上是ServiceStack.Text本身被链接器搞砸了。JsonReader<T>.GetParseFn()是通过反射访问的，这显然导致了它的遗漏。

我去掉了LinkerDescriptionXML，并添加了一个类，如下所示：

using ServiceStack.Text.Common;
using ServiceStack.Text.Json;
namespace MyApp
{
    public class LinkerInclude
    {
        public ParseStringDelegate IncludeJsonReader<T>()
        {
            return JsonReader<T>.GetParseFn();
        }
    }
}

Answer 2

最后，我发现了更多的问题，这些问题我无法通过之前的答案中的代码方法解决。这是因为链接器忽略的某些类是ServiceStack.Text程序集的内部类。

最终，我恢复使用链接描述XML。它看起来是这样的：

<?xml version="1.0" encoding="utf-8" ?>
<linker>
  <assembly fullname="ServiceStack.Text">
    <type fullname="ServiceStack.Text.Json.JsonReader`1" >
      <method name="GetParseFn" />
    </type>
    <type fullname="ServiceStack.Text.Common.DeserializeListWithElements`2" >
      <method name="ParseGenericList" />
    </type>
    <type fullname="ServiceStack.Text.Common.WriteListsOfElements`2" >
      <method name="WriteList" />
      <method name="WriteArray" />
    </type>
  </assembly>
</linker>

我在博客中谈到了如何在这里实现这一点。