异常Exception（二）

学习网址：https://docs.microsoft.com/zh-cn/dotnet/standard/exceptions/exception-class-and-properties

了解Exception的常见属性。

Data：Exception的键/值对数据。

using System;
using System.Collections;

namespace ConsoleApp5
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                NestedRoutine1(true);
            }
            catch (Exception e)
            {
                // 打印Data
                if (e.Data.Count > 0)
                {
                    foreach (DictionaryEntry de in e.Data)
                        Console.WriteLine("    Key: {0,-20}      Value: {1}",
                                          "'" + de.Key.ToString() + "'", de.Value);
                }
            }
            Console.ReadLine();
        }
       

        public static void NestedRoutine1(bool displayDetails)
        {
            try
            {
                NestedRoutine2(displayDetails);
            }
            catch (Exception e)
            {
                // 给data添加异常信息
                e.Data["ExtraInfo"] = "Information from NestedRoutine1.";
                e.Data.Add("MoreExtraInfo", "More information from NestedRoutine1.");
                // throw后面不加异常对象，默认是当前异常
                throw;
            }
        }

        public static void NestedRoutine2(bool displayDetails)
        {
            Exception e = new Exception("This statement is the original exception message.");
            if (displayDetails)
            {
                // 给data添加异常信息
                string s = "Information from NestedRoutine2.";
                int i = -903;
                DateTime dt = DateTime.Now;
                e.Data.Add("stringInfo", s);
                e.Data["IntInfo"] = i;
                e.Data["DateTimeInfo"] = dt;
            }
            throw e;
        }
    }
}

HelpLink：指向帮助文件的 URL，没有值就为null。

InnerException：内部异常信息，当前异常可能是其他异常导致的，记录当前异常的原始异常。

代码：

using System;
using System.Collections;

namespace ConsoleApp5
{
    class Program
    {
        static void Main(string[] args)
        {           
            try
            {
                CatchInner();
            }
            catch (AppException e)
            {
                Console.WriteLine("外层异常信息: {0}", e.Message);
                if (e.InnerException != null)
                    Console.WriteLine("Inner exception: {0}", e.InnerException);
            }
            Console.ReadLine();
        }

        public static void ThrowInner()
        {
            throw new AppException("ThrowInner内部异常信息");
        }

        public static void CatchInner()
        {
            try
            {
                ThrowInner();
            }
            catch (AppException e)
            {
                throw new AppException("CatchInner外部异常信息", e);
            }
        }
    }

    public class AppException : Exception
    {
        public AppException(String message) : base(message)
        { }

        public AppException(String message, Exception inner) : base(message, inner) { }
    }
}