我想在动态变量中反序列化一个json文档，但它会抛出
错误：
byte[] decodedString = Base64.decode(byte_arr, Base64.DEFAULT);代码：
[MonoDroid] UNHANDLED EXCEPTION:
[MonoDroid] System.InvalidCastException: Cannot cast from source type to destination type.
[MonoDroid] at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () <IL 0x00011, 0x00078>
[MonoDroid] at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>m__0 (object) <IL 0x00006, 0x0006b>
[MonoDroid] at Android.App.SyncContext/<Post>c__AnonStorey0.<>m__0 () [0x00000] in /Users/builder/data/lanes/1879/5f55a9ef/source/monodroid/src/Mono.Android/src/Android.App/SyncContext.cs:18
[MonoDroid] at Java.Lang.Thread/RunnableImplementor.Run () [0x0000b] in /Users/builder/data/lanes/1879/5f55a9ef/source/monodroid/src/Mono.Android/src/Java.Lang/Thread.cs:36
[MonoDroid] at Java.Lang.IRunnableInvoker.n_Run (intptr,intptr) [0x00009] in /Users/builder/data/lanes/1879/5f55a9ef/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Java.Lang.IRunnable.cs:71
[MonoDroid] at (wrapper dynamic-method) object.461b928a-1fde-4250-8fe8-4ab69b1f0acd (intptr,intptr) <IL 0x00011, 0x0003b>
[art] JNI RegisterNativeMethods: attempt to register 0 native methods for md52ce486a14f4bcd95899665e9d932190b.JavaProxyThrowable
[AndroidRuntime] Shutting down VM
Json看起来像这样：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Json;
using System.Net;
using System.IO;
using System.Threading.Tasks;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Newtonsoft.Json;
namespace HomecheckApp {
[Activity(Label = "LoginActivity", MainLauncher = true)]
public class LoginActivity : Activity {
private const string apiKey = "*********************************************";
protected override void OnCreate(Bundle bundle) {
base.OnCreate(bundle);
SetContentView(Resource.Layout.Login);
EditText email = FindViewById<EditText>(Resource.Id.editEmail);
EditText password = FindViewById<EditText>(Resource.Id.editPassword);
Button loginButton = FindViewById<Button>(Resource.Id.loginButton);
// string url = "http://homecheck.192.168.1.102.xip.io/appapi/finduser?email" + email.Text + "&pass=" + password.Text + "&key=" + apiKey;
loginButton.Click += async (sender, e) => {
string url = "http://homecheck.********.eu/appapi/finduser?email=" + email.Text + "&pass=" + password.Text + "&key=" + apiKey;
JsonValue json = await FetchUserAsync(url, apiKey);
//This is where it breaks
dynamic userInfo = JsonConvert.DeserializeObject(json);
//*********
Console.WriteLine("Email is: " + userInfo.email);
};
}
private async Task<JsonValue> FetchUserAsync(string url, string apiKey) {
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(new Uri(url));
request.ContentType = "application/json";
request.Method = "POST";
using(WebResponse response = await request.GetResponseAsync()) {
using(Stream stream = response.GetResponseStream()) {
JsonValue jsonResponse = await Task.Run(() => JsonObject.Load(stream));
Console.WriteLine(jsonResponse.ToString());
return jsonResponse;
}
}
}
}
}
当我尝试使用{"error":false,"id":3,"name":"***********","surname":"*******","email":"***********@gmail.com","gsm":"1239102312930","company":"","address":3}
反序列化时出现相同的错误。这是IDE本身的问题（我使用的是Xamarin Studio）还是其他的东西？
答案 0 :(得分：1)
JsonConvert.DeserializeObject()将string作为其第一个参数。但是，您提供的类型为JsonValue的对象。我不太确定为什么编译器甚至允许这样做，但这很可能是你问题的根源。
简单地改变
dynamic userInfo = JsonConvert.DeserializeObject(json);
到
dynamic userInfo = JsonConvert.DeserializeObject(json.ToString());
至少应该修复你的异常。然而，这可能不是最优雅的解决方案。