学步园

前面做一个基于sybase的mis系统， 由于sybase的后台是cp850编码，而.net平台不支持cp850编码。所以在程序中所有从数据库读出的中文都显示为''?''。
于是考虑在.net 平台中转换字符编码。于是查看了.net中字符编码的类System.Text.Encoding
里面支持的字符集编码有ibm850,没有cp850,后来查看资料才知道原来这两个名字指的是同一种编码规范。
于是开始进行编码转换，首先找到一个java的程序：

        public String CP850ToGB2312(String str)
        ...{
            try
            ...{
                byte[] temp = str.getBytes("cp850");
                String result = new String(temp, "gb2312");
                return result;
            }
            catch (UnsupportedEncodingException ex)
            ...{ return null; }
        }
        public String GB2312ToCP850(String str)
        ...{
            try
            ...{
                byte[] temp = str.getBytes("gb2312");
                String result = new String(temp, "cp850");
                return result;
            }
            catch (UnsupportedEncodingException ex)
            ...{
                return null;
            }
        }
 

然后在根据查找的System.Text.Encoding类的属性，方法写了如下的转换程序：

        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;
            }
        }
 

主要使用的就是获取编码方式的类对象，
 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。

        static void Main(string[] args)
        {
            FileStream fs;
            string fileName = "C://test.xml";
            string message = "呵呵";

            string m=System.Web.HttpUtility.UrlEncode(message, System.Text.Encoding.UTF8);

            fs = new FileStream(fileName, FileMode.OpenOrCreate);
            StreamWriter sw = new StreamWriter(fs);
            fs.Seek(0, SeekOrigin.End);

            sw.WriteLine("<?xml version=/"1.0/" encoding=/"UTF-8/"?><menu>" + message + "</menu>");
            sw.Close();
            fs.Close();
            Console.Read();

        }
        private static string ToGB2312(string utfInfo)
        {
            string gb2312Info = string.Empty;
            Encoding utf8 = Encoding.UTF8;
            Encoding gb2312 = Encoding.GetEncoding("gb2312");
            byte[] unicodeBytes = utf8.GetBytes(utfInfo);
            byte[] asciiBytes = Encoding.Convert(utf8, gb2312, unicodeBytes);
            char[] asciiChars = new char[gb2312.GetCharCount(asciiBytes, 0, asciiBytes.Length)];
            gb2312.GetChars(asciiBytes, 0, asciiBytes.Length, asciiChars, 0);
            string gb2312info = new string(asciiChars);
            return gb2312info;
        }

        private static string ToUTF8(string gb2312Info)
        {
            string utf8Info = string.Empty;
            Encoding utf8 = Encoding.UTF8;
            Encoding gb2312 = Encoding.GetEncoding("gb2312");
            byte[] unicodeBytes = gb2312.GetBytes(gb2312Info);
            byte[] asciiBytes = Encoding.Convert(gb2312, utf8, unicodeBytes);
            char[] asciiChars = new char[utf8.GetCharCount(asciiBytes, 0, asciiBytes.Length)];
            utf8.GetChars(asciiBytes, 0, asciiBytes.Length, asciiChars, 0);
            string utf8info = new string(asciiChars);
            return utf8info;
        }