日志写入到RichTextBox中展示

# 传统方式
```java
  public enum LogLevel
  {
      Info,
      Error
  }
  /// <summary>
  /// 日志写入到RichTextBox中展示
  /// </summary>
  public class RichTextBoxLogHelper
  {
      private RichTextBox _richTextBox;

public RichTextBoxLogHelper(RichTextBox richTextBox)
      {
          _richTextBox = richTextBox;
      }
      public void Log(string message, LogLevel logLevel = LogLevel.Info)
      {
          string logMessage = $"{DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")} - {logLevel.ToString().ToUpper()} - {message}";
          if (_richTextBox.InvokeRequired)
          {
              _richTextBox.Invoke(new MethodInvoker(() => Log(logMessage, logLevel)));
          }
          else
          {
              _richTextBox.SelectionStart = _richTextBox.TextLength;
              _richTextBox.SelectionLength = 0;

switch (logLevel)
              {
                  case LogLevel.Info:
                      _richTextBox.SelectionColor = Color.Black;
                      break;
                  case LogLevel.Error:
                      _richTextBox.SelectionColor = Color.Red;
                      break;
              }

_richTextBox.AppendText(logMessage);
              _richTextBox.SelectionColor = _richTextBox.ForeColor;
              _richTextBox.ScrollToCaret();
          }
      }
  }
```

# 推荐 扩展方法
```java
 /// <summary>
 /// 推荐使用此方法
 /// </summary>
 public static class RichTextBoxExtensions
 {
     public static void Log(this RichTextBox _richTextBox, string message, LogLevel logLevel = LogLevel.Info)
     {
         string logMessage = $"{DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")} - {logLevel.ToString().ToUpper()} - {message}";
         if (_richTextBox.InvokeRequired)
         {
             _richTextBox.Invoke(new MethodInvoker(() => Log(_richTextBox, logMessage, logLevel)));
         }
         else
         {
             _richTextBox.SelectionStart = _richTextBox.TextLength;
             _richTextBox.SelectionLength = 0;

switch (logLevel)
             {
                 case LogLevel.Info:
                     _richTextBox.SelectionColor = Color.Black;
                     break;
                 case LogLevel.Error:
                     _richTextBox.SelectionColor = Color.Red;
                     break;
             }

_richTextBox.AppendText(logMessage + Environment.NewLine);
             _richTextBox.SelectionColor = _richTextBox.ForeColor;
             _richTextBox.ScrollToCaret();
         }
     }
 }
```
# 调用示例
```java
 public partial class Form1 : Form
 {
     private LogHelper _logHelper;
     public Form1()
     {
         InitializeComponent();
     }

private void button1_Click(object sender, EventArgs e)
     {
         try
         {
             // 模拟错误
             throw new Exception("这是一个错误");
         }
         catch (Exception ex)
         {
             _logHelper.Log(ex.ToString(), LogLevel.Error);
         }
     }

private void button2_Click(object sender, EventArgs e)
     {
         for (int i = 0; i < 10; i++)
         {
             _logHelper.Log("应用程序启动" + i.ToString());
         }
     }

private void Form1_Load(object sender, EventArgs e)
     {
         _logHelper = new LogHelper(richTextBox1);

// 模拟日志输出
         _logHelper.Log("应用程序启动");
         _logHelper.Log("这是一条信息日志");
         _logHelper.Log("这是一条错误日志", LogLevel.Error);
     }
 }
```