// 获得资源。返回字符串版本。Cache版本。
// return:
// -1 出错。具体出错原因在this.ErrorCode中。this.ErrorInfo中有出错信息。
// 0 成功
public long GetRes(
CfgCache cache,
string strPath,
string strStyle,
out string strResult,
out string strMetaData,
out byte[] baOutputTimeStamp,
out string strOutputResPath,
out string strError)
{
byte[] cached_timestamp = null;
string strTimeStamp;
string strLocalName;
// bool bExistInCache = false;
string strFullPath = this.Url + "?" + strPath;
if (StringUtil.IsInList("forceget", strStyle) == true)
{
// 强制获取
StringUtil.RemoveFromInList("forceget",
true,
ref strStyle);
goto GETDATA;
}
// 从cache中得到timestamp
// return:
// -1 error
// 0 not found
// 1 found
int nRet = cache.FindLocalFile(strFullPath,
out strLocalName,
out strTimeStamp);
if (nRet == -1)
{
strResult = "";
strMetaData = "";
baOutputTimeStamp = null;
strOutputResPath = "";
strError = "CfgCache 尚未初始化";
return -1;
}
if (nRet == 1)
{
Debug.Assert(strLocalName != "", "FindLocalFile()返回的strLocalName为空");
if (strTimeStamp == "")
goto GETDATA; // 时间戳不对, 那就只好重新获取服务器端内容
Debug.Assert(strTimeStamp != "", "FindLocalFile()获得的strTimeStamp为空");
cached_timestamp = ByteArray.GetTimeStampByteArray(strTimeStamp);
// bExistInCache = true;
}
else
goto GETDATA;
// 探测时间戳关系
string strNewStyle = strStyle;
/*
StringUtil.RemoveFromInList("metadata",
true,
ref strNewStyle); // 不要metadata
*/
StringUtil.RemoveFromInList("content,data,metadata", // 2012/12/31 BUG 以前忘记了加入content
true,
ref strNewStyle); // 不要数据体和metadata
long lRet = GetRes(strPath,
strNewStyle,
out strResult,
out strMetaData,
out baOutputTimeStamp,
out strOutputResPath,
out strError);
if (lRet == -1)
return -1;
// 如果证明timestamp没有变化, 但是本次并未返回内容,则从cache中取原来的内容
if (ByteArray.Compare(baOutputTimeStamp, cached_timestamp) == 0) // 时间戳相等
{
Debug.Assert(strLocalName != "", "strLocalName不应为空");
StreamReader sr = null;
try
{
sr = new StreamReader(strLocalName, Encoding.UTF8);
}
catch (Exception ex)
{
strError = ex.Message;
return -1;
}
strResult = sr.ReadToEnd();
sr.Close();
return 0; // 以无错误姿态返回
}
GETDATA:
// 重新正式获取内容
lRet = GetRes(strPath,
strStyle,
out strResult,
out strMetaData,
out baOutputTimeStamp,
out strOutputResPath,
out strError);
if (lRet == -1)
return -1;
// 因为时间戳不匹配而新获得了内容
// 保存到cache
cache.PrepareLocalFile(strFullPath, out strLocalName);
Debug.Assert(strLocalName != "", "PrepareLocalFile()返回的strLocalName为空");
// 写入文件,以便以后从cache获取
StreamWriter sw = new StreamWriter(strLocalName,
false, // append
System.Text.Encoding.UTF8);
sw.Write(strResult);
sw.Close();
sw = null;
Debug.Assert(baOutputTimeStamp != null, "下层GetRes()返回的baOutputTimeStamp为空");
nRet = cache.SetTimeStamp(strFullPath,
ByteArray.GetHexTimeStampString(baOutputTimeStamp),
out strError);
if (nRet == -1)
return -1;
return lRet;
}