异常Exception（三）

using System;
using System.Collections;
using System.IO;

namespace ConsoleApp5
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                using (StreamReader sr = File.OpenText("data.txt"))
                {
                    Console.WriteLine($"The first line of this file is {sr.ReadLine()}");
                }
            }
            catch (FileNotFoundException e)
            {
                Console.WriteLine($"The file was not found: ‘{e}‘");
            }
            catch (DirectoryNotFoundException e)
            {
                Console.WriteLine($"The directory was not found: ‘{e}‘");
            }
            catch (IOException e)
            {
                Console.WriteLine($"The file could not be opened: ‘{e}‘");
            }
            catch (Exception e)
            {
                Console.WriteLine($"其他异常：{e}");
            }
            Console.ReadLine();
        }    
    }
}

using System;
using System.IO;

namespace ConsoleApp5
{
    class Program
    {
        static void Main(string[] args)
        {
            FileStream fs=null;
            try
            {
                fs = new FileStream(@"C:\temp\data.txt", FileMode.Open);
                var sr = new StreamReader(fs);

                string line = sr.ReadLine();
                Console.WriteLine(line);
            }
            catch (FileNotFoundException e)
            {
                Console.WriteLine($"[Data File Missing] {e}");
                throw new FileNotFoundException(@"[data.txt not in c:\temp directory]", e);
                // 直接使用throw相当抛出当前异常。
            }
            finally
            {
                if (fs != null)
                {
                    fs.Close();
                    Console.WriteLine("关掉");
                }
            }
            Console.ReadLine();
        }    
    }
}