UTF-8编码字符串：棰?，如何还原为GB2312字符串：题-

[justduit]

原标题为：题-
通过项目里的FLASH组件，传递过来了UTF-8编码字符串：棰?
如何还原为GB2312编码字符串：题-

[兔子-顾问]

byte[] dest = Encoding.Convert(Encoding.UTF8,Encoding.GetEncoding("GB2312"),Encoding.UTF8.GetBytes(yourUtf8String));
string result = Encoding.GetEncoding("GB2312").GetString(dest);

[justduit]

[Quote=引用 1 楼 wuyazhe 的回复:]

C# code
byte[] dest = Encoding.Convert(Encoding.UTF8,Encoding.GetEncoding("GB2312"),Encoding.UTF8.GetBytes(yourUtf8String));
string result = Encoding.GetEncoding("GB2312").GetString(dest);
[/Quote]

使用后，输出结果还是：棰?，没有还原回去。

[qqiuzaihui]

            string name = Encoding.GetEncoding("GB2312").GetString(Encoding.UTF8.GetBytes(yourUtf8String));

[justduit]

    protected void Page_Load(object sender, EventArgs e)
    {
        string title = "北-";
        string utf = TransGB2312ToUTF8(title);
        Response.Write(string.Format("gb title : {0}", title));
        Response.Write("<br />");
        Response.Write(string.Format("utf title : {0}", utf));
        Response.Write("<br />");
        Response.Write(string.Format("trans title : {0}", Trans(utf)));
        Response.Write("<br />");
        Response.Write(string.Format("trans first title : {0}", TransFirst(utf)));
        Response.Write("<br />");
        Response.Write(string.Format("trans second title : {0}", TransSecond(utf)));
        Response.Write("<br />");
        title = "北京";
        utf = TransGB2312ToUTF8(title);
        Response.Write(string.Format("gb title : {0}", title));
        Response.Write("<br />");
        Response.Write(string.Format("utf title : {0}", utf));
        Response.Write("<br />");
        Response.Write(string.Format("trans title : {0}", Trans(utf)));
        Response.Write("<br />");
        Response.Write(string.Format("trans first title : {0}", TransFirst(utf)));
        Response.Write("<br />");
        Response.Write(string.Format("trans second title : {0}", TransSecond(utf)));
        Response.Write("<br />");
    }

    /// <summary>
    /// GB2312转UTF8
    /// </summary>
    /// <param name="input">源字符串</param>
    /// <returns></returns>
    public string TransGB2312ToUTF8(string input)
    {
        string reResult = string.Empty;
        Encoding gb = Encoding.GetEncoding("gb2312");
        byte[] bt = Encoding.Convert(Encoding.Default, Encoding.UTF8, gb.GetBytes(input));
        reResult = gb.GetString(bt);
        return reResult;
    }

    /// <summary>
    /// UTF8转GB2312
    /// </summary>
    /// <param name="input">源字符串</param>
    /// <returns></returns>
    public string Trans(string input)
    {
        string res = input;
        UTF8Encoding utf = new UTF8Encoding();
        byte[] bt = Encoding.Convert(Encoding.UTF8, Encoding.Default, utf.GetBytes(res));
        res = utf.GetString(bt);
        return res;
    }


    /// <summary>
    /// UTF8转GB2312(方法一)
    /// </summary>
    /// <param name="input">源字符串</param>
    /// <returns></returns>
    public string TransFirst(string input)
    {
        string res = input;
        byte[] dest = Encoding.Convert(Encoding.UTF8, Encoding.GetEncoding("GB2312"), Encoding.UTF8.GetBytes(res));
        res = Encoding.GetEncoding("GB2312").GetString(dest);
        return res;
    }

    /// <summary>
    /// UTF8转GB2312(方法二)
    /// </summary>
    /// <param name="input">源字符串</param>
    /// <returns></returns>
    public string TransSecond(string input)
    {
        string res = input;
        res = Encoding.GetEncoding("GB2312").GetString(Encoding.UTF8.GetBytes(res));
        return res;
    }

以上输出结果为：
gb title : 北-
utf title : 鍖?
trans title : ??
trans first title : 鍖?
trans second title : 閸?
gb title : 北京
utf title : 鍖椾含
trans title : 北京
trans first title : 鍖椾含
trans second title : 閸栨ぞ鍚?

当原字符串为偶数个中文时，用Trans方法可以还原回去
当原字符串为奇数个中文+字母|符号|数字，所有的方法都不能还原回去

这是否在转码的过程当中丢失了数据？

[gomoku]

没有“UTF-8编码字符串”这种说法。可以说“UTF-8编码字节串”。

.net的字符串都是UTF-16编码的。
某些组合是不被UTF-16认可的，所以，不是任何的字节串都能用.net的字符串表示的。