StringWriter 和StringBuilder 什么关系?

[tinranqi]

StringWriter 和StringBuilder 什么关系?
看了msdn依然的不明白

[堆代码的爱因斯坦]

using System;
using System.IO;
using System.Text;

class StrWriter
{
static void Main()
{
StringBuilder strBuilder =
new StringBuilder("file path characters are: ");
StringWriter strWriter = new StringWriter(strBuilder);

strWriter.Write(
Path.InvalidPathChars, 0, Path.InvalidPathChars.Length);

strWriter.Close();

// Since the StringWriter is closed, an exception will
// be thrown if the Write method is called. However,
// the StringBuilder can still manipulate the string.
strBuilder.Insert(0, "Invalid ");
Console.WriteLine(strWriter.ToString());
}
}

[tinranqi]

能详细说下不？
感觉他们差不多，
StringWriter 的Write和StringBuilder 的Append感觉是一样的
他们都是用来放字符串的

[tinranqi]

  System.Globalization.CultureInfo myCItrad = new System.Globalization.CultureInfo("ZH-CN", true);
  System.IO.StringWriter oStringWriter = new System.IO.StringWriter(myCItrad);
  System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);
  tb.RenderControl(oHtmlTextWriter);//将服务器控件的内容输出

还有这段代码
将tb控件中的内容放入oHtmlTextWriter对象中
oHtmlTextWriter对象自动将tb中的内容以HTML的形式呈现出来？呈现在哪？
上面又有用oStringWriter来初始化这个oHtmlTextWriter对象，msdn中说的是初始化使用默认制表符字符串的 HtmlTextWriter 类的新实例。 这个让我很费解？
求指点，比较菜。。。。

[挨踢直男]

stringwriter用来操作stringbuilder
好比 streamwriter 和 stream