private static string DecodeField(string str) // 将字段值解码(含非ASCII码时)
{
string decodedField = "";
string[] fields = str.Split('?'); // 会分成5段，第2段为字符编码，第3段为字节编码，第4段为内容
if (fields.Length == 5)
{
string encodeType1 = fields[1]; // 字符编码
string encodeType2 = fields[2];
if (encodeType2 == "B") // 如果是Base64编码
{
decodedField += MyEncoder.DecodeWithBase64(fields[3], Encoding.GetEncoding(encodeType1));
// 先转为字节数组，再以GBK解码
}
else if (encodeType2 == "Q") // 如果是Quoted-printable编码
{
decodedField += MyEncoder.DecodeWithQP(fields[3], Encoding.GetEncoding(encodeType1));
}
else // 暂时不处理其他类型的编码
{
decodedField += (fields[3] + " ");
}
}
else // 不带编码，纯英文
{
decodedField = str + " ";
}
return(decodedField);
}
/* 将字符串转为信体结构 */
public static Body GetBody(string rawStr)
{
Body body = new Body();
string unfoledRawStr = rawStr.Replace("\r\n ", " ").Replace("\r\n\t", " "); // 展开字段
/* 处理Content-Type和Transfer-Encoding-Type */
string contentTypePattern = "(\r\n|\n)Content-Type:([^;]*);(.*)(\r\n|\n)"; // Content-Type匹配模式
string encodingTypePattern = "(\r\n|\n)Content-Transfer-Encoding:[ ]*(.*)[ ]*(\r\n|\n)"; // Transfer-Encoding-Type匹配模式
Match conmatch = Regex.Match(unfoledRawStr, contentTypePattern);
Match enmatch = Regex.Match(unfoledRawStr, encodingTypePattern);
if (!conmatch.Success || !enmatch.Success) // 两个必有属性必须匹配成功
{
return(body);
}
string contentTypeStr = conmatch.Groups[2].Value.Trim().Trim('"').ToLower(); // 主属性
string otherAttributes = conmatch.Groups[3].Value; // 其他属性
body.ContentType = GetContentType(contentTypeStr); // 添加Content-Type
body.EncodeType = GetEncodingType(enmatch.Groups[2].Value.Trim().Trim('"')); // 添加Transfer-Encoding-Type
/* 依据不同的内容类型分别处理 */
if (contentTypeStr.Contains("multipart")) // 混合类型
{
body.Boundary = GetBoundary(otherAttributes);
body.Charset = GetCharset(otherAttributes);
string boundary = "--" + body.Boundary; // 分割字符串
string endBoundary = "--" + body.Boundary + "--"; // 结尾字符串
string[] parts = Regex.Split(rawStr.Replace(endBoundary, boundary), boundary); // 按边界切割
/* 处理每个子部分 */
for (int i = 1; i < parts.Length; i++) // 忽略第一部分，因为是信头
{
if (parts[i] == "\r\n" || parts[i] == "\r\n\r\n" || parts[i] == "") // 跳过无意义的部分
{
continue;
}
body.SubBodies.Add(GetBody(parts[i])); // 递归处理子信体
}
}
else if (contentTypeStr.Contains("text")) // 文本类型
{
body.Charset = GetCharset(otherAttributes);
string[] strs = Regex.Split(rawStr, "\r\n\r\n");
string data = "";
for (int i = 1; i < strs.Length; i++) // 跳过信头
{
if (strs[i] == "\r\n" || strs[i] == "\r\n\r\n" || strs[i] == "") // 跳过无意义的部分
{
continue;
}
string contentStr;
switch (body.EncodeType) // 依据不同编码进行解码
{
case Transfer_Encoding.Base64:
contentStr = strs[i].Replace("\r\n", ""); // 去除所有换行标记
data += (MyEncoder.DecodeWithBase64(contentStr, body.Charset) + "\n");
break;
case Transfer_Encoding.Quoted_Printable:
strs[i] += "\r\n"; // 每段结尾补一个\r\n，以避免QP编码换行标志被破坏
contentStr = strs[i].Replace("=\r\n", "").Replace("\r\n", ""); // 去除所有换行标记
data += (MyEncoder.DecodeWithQP(contentStr, body.Charset) + "\n");
break;
case Transfer_Encoding.Bit8:
contentStr = strs[i].Replace("\r\n", ""); // 去除所有换行标记
data += (MyEncoder.DecodeWithBit8(contentStr, body.Charset) + "\n");
break;
case Transfer_Encoding.Bit7:
contentStr = strs[i].Replace("\r\n", ""); // 去除所有换行标记
data += (contentStr + "\n");
break;
default:
contentStr = strs[i].Replace("\r\n", ""); // 去除所有换行标记
data += (contentStr + "\n");
break;
}
}
body.Data = body.Charset.GetBytes(data);
}
else if (contentTypeStr.Contains("application")) // 应用类型
{
body.Name = GetName(otherAttributes);
body.Disposition = GetDisposition(rawStr);
string[] paras = Regex.Split(rawStr, "\r\n\r\n");
byte[] data;
switch (body.EncodeType) // 依据不同编码进行解码
{
case Transfer_Encoding.Base64:
data = MyEncoder.DecodeWithBase64(paras[1].Replace("\r\n", ""));
break;
case Transfer_Encoding.Quoted_Printable:
data = MyEncoder.DecodeWithQP(paras[1].Replace("=\r\n", "").Replace("\r\n", ""));
break;
case Transfer_Encoding.Bit8:
data = MyEncoder.DecodeWithBit8(paras[1].Replace("\r\n", ""));
break;
case Transfer_Encoding.Bit7:
data = Encoding.Default.GetBytes(paras[1].Replace("\r\n", ""));
break;
default:
data = Encoding.Default.GetBytes(paras[1].Replace("\r\n", ""));
break;
}
body.Data = data;
}
else if (contentTypeStr.Contains("image")) // 图片类型
{
body.Name = GetName(otherAttributes);
string[] paras = Regex.Split(rawStr, "\r\n\r\n");
byte[] data;
switch (body.EncodeType) // 依据不同编码进行解码
{
case Transfer_Encoding.Base64:
data = MyEncoder.DecodeWithBase64(paras[1].Replace("\r\n", ""));
break;
case Transfer_Encoding.Quoted_Printable:
data = MyEncoder.DecodeWithQP(paras[1].Replace("=\r\n", "").Replace("\r\n", ""));
break;
case Transfer_Encoding.Bit8:
data = MyEncoder.DecodeWithBit8(paras[1].Replace("\r\n", ""));
break;
case Transfer_Encoding.Bit7:
data = Encoding.Default.GetBytes(paras[1].Replace("\r\n", ""));
break;
default:
data = Encoding.Default.GetBytes(paras[1].Replace("\r\n", ""));
break;
}
body.Data = data;
}
else
{
}
return(body);
}
