C#如何改变字符串编码

public string UTF8ToGB2312(string str)
        {
            try
            {   
                Encoding utf8 = Encoding.GetEncoding(65001);
                Encoding gb2312 = Encoding.GetEncoding("gb2312");//Encoding.Default ,936
                byte[] temp = utf8.GetBytes(str);
                byte[] temp1 = Encoding.Convert(utf8, gb2312, temp);
                string result = gb2312.GetString(temp1);
                return result;
            }
            catch  (Exception ex)//(UnsupportedEncodingException ex)
            {
                MessageBox.Show(ex.ToString());
                return null;
            }
        }
        public string GB2312ToUTF8(string str)
        {
            try
            {
                Encoding uft8 = Encoding.GetEncoding(65001);
                Encoding gb2312 = Encoding.GetEncoding("gb2312");
                byte[] temp = gb2312.GetBytes(str);
                MessageBox.Show("gb2312的编码的字节个数：" + temp.Length);
                for (int i = 0; i < temp.Length; i++)
                {
                    MessageBox.Show(Convert.ToUInt16(temp[i]).ToString());
                }   
                byte[] temp1 = Encoding.Convert(gb2312, uft8, temp);
                MessageBox.Show("uft8的编码的字节个数：" + temp1.Length);
                for (int i = 0; i < temp1.Length; i++)
                {
                    MessageBox.Show(Convert.ToUInt16(temp1[i]).ToString());
                }              
                string result = uft8.GetString(temp1);
                return result;
            }
            catch  (Exception ex)//(UnsupportedEncodingException ex)
            {
                MessageBox.Show(ex.ToString());
                return null;
            }
        }

代码说明：

 Encoding utf8 = Encoding.GetEncoding(65001);//使用code page

 Encoding gb2312 = Encoding.GetEncoding("gb2312");//通过bodyname

获取字符编码字节序列：byte[] temp=utf8.GetBytes(str);

编码方式转换：byte[] temp1=Encoding.Convert(utf8, gb2312, temp);

获取编码的字符串：string str1=gb2312.GetString(temp1);

这样即完成了字符编码的转换。

Encoding.Default在 简体中文os中一般是gb2312格式。