CSharp-Learning/lessons/Lesson08/Program.cs

using System;

namespace Lesson08
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("=== 异常处理演示 ===\n");

            // ========== 基本 try-catch ==========
            Console.WriteLine("--- 基本 try-catch ---");
            try
            {
                int[] numbers = { 1, 2, 3 };
                Console.WriteLine(numbers[10]);
            }
            catch (Exception ex)
            {
                Console.WriteLine($"捕获异常: {ex.Message}");
            }

            // ========== 捕获特定异常 ==========
            Console.WriteLine("\n--- 捕获特定异常 ---");
            string[] inputs = { "123", "abc", "9999999999999" };

            foreach (string input in inputs)
            {
                try
                {
                    int num = int.Parse(input);
                    Console.WriteLine($"转换成功: {num}");
                }
                catch (FormatException)
                {
                    Console.WriteLine($"\"{input}\" 格式错误，不是数字");
                }
                catch (OverflowException)
                {
                    Console.WriteLine($"\"{input}\" 数字太大");
                }
            }

            // ========== throw 抛出异常 ==========
            Console.WriteLine("\n--- throw 抛出异常 ---");
            try
            {
                SetAge(-5);
            }
            catch (ArgumentException ex)
            {
                Console.WriteLine($"捕获到: {ex.Message}");
            }

            try
            {
                SetAge(200);
            }
            catch (ArgumentException ex)
            {
                Console.WriteLine($"捕获到: {ex.Message}");
            }

            SetAge(25);  // 正常
            SetAge(0);   // 正常

            // ========== 实际项目场景 ==========
            Console.WriteLine("\n--- 设备连接场景 ---");
            MicrophoneDevice mic = new MicrophoneDevice("USB麦克风");

            // 场景1：设备未连接
            try
            {
                mic.StartListening();
            }
            catch (DeviceNotConnectedException ex)
            {
                Console.WriteLine($"错误: {ex.Message}");
                Console.WriteLine("建议：请检查设备连接");
            }

            // 场景2：连接后正常操作
            mic.Connect();
            try
            {
                mic.StartListening();
                Console.WriteLine("麦克风开始监听...");
                mic.StopListening();
                Console.WriteLine("麦克风停止监听...");
            }
            catch (DeviceNotConnectedException ex)
            {
                Console.WriteLine($"错误: {ex.Message}");
            }
            finally
            {
                mic.Disconnect();
                Console.WriteLine("设备已断开");
            }

            // ========== finally 演示 ==========
            Console.WriteLine("\n--- finally 执行时机 ---");
            try
            {
                Console.WriteLine("try 块执行");
                // int x = 1 / 0;  // 解开这行会跳到 catch
            }
            catch
            {
                Console.WriteLine("catch 块执行");
            }
            finally
            {
                Console.WriteLine("finally 块总是执行");
            }

            Console.WriteLine("\n=== 演示完成 ===");
            Console.ReadLine();
        }

        // ========== throw 示例 ==========
        static void SetAge(int age)
        {
            if (age < 0 || age > 150)
            {
                throw new ArgumentException($"年龄必须在 0-150 之间，当前: {age}");
            }
            Console.WriteLine($"年龄设置为: {age}");
        }
    }

    // ========== 自定义异常 ==========
    class DeviceNotConnectedException : Exception
    {
        public DeviceNotConnectedException(string message) : base(message) { }
        public DeviceNotConnectedException(string message, Exception inner) : base(message, inner) { }
    }

    // ========== 设备类 ==========
    class MicrophoneDevice
    {
        private string name;
        private bool isConnected;
        private bool isListening;

        public MicrophoneDevice(string name)
        {
            this.name = name;
            this.isConnected = false;
            this.isListening = false;
        }

        public void Connect()
        {
            isConnected = true;
            Console.WriteLine($"[{name}] 设备已连接");
        }

        public void Disconnect()
        {
            isConnected = false;
            Console.WriteLine($"[{name}] 设备已断开");
        }

        public void StartListening()
        {
            if (!isConnected)
            {
                throw new DeviceNotConnectedException($"{name} 未连接，无法开始监听");
            }
            if (isListening)
            {
                throw new InvalidOperationException($"{name} 已经在监听中");
            }
            isListening = true;
        }

        public void StopListening()
        {
            if (!isListening)
            {
                throw new InvalidOperationException($"{name} 没有在监听");
            }
            isListening = false;
        }
    }
}