dan*_*ana 33 .net asp.net lucene solr lucene.net
我听说过Lucene.Net,我听说过Apache Tika.问题是 - 如何使用C#和Java索引这些文档？我认为问题在于没有.Net等效的Tika从这些文档类型中提取相关文本.
更新 - 2011年2月5日
基于给定的响应,似乎目前不是Tika 的原生 .Net等价物.提到了两个有趣的项目,每个项目各有趣:
鉴于上述两个项目,我看到了几个选项.为了提取文本,我可以a)使用Omega正在使用的相同组件或b)使用IKVM来运行Tika.对我来说,选项b)看起来更干净,因为只有2个依赖项.
有趣的是,现在有几个搜索引擎可能可以从.Net使用.有Xapian,Lucene.Net甚至Lucene(使用IKVM).
更新 - 2011年2月7日
另一个答案是建议我查看ifilters.事实证明,这就是MS用于Windows搜索,因此Office ifilter随时可用.此外,还有一些PDF ifilters.缺点是它们是在非托管代码中实现的,因此使用COM互操作是必要的.我在DotLucene.NET档案中找到了以下代码snippit(不再是活动项目):
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;
namespace IFilter
{
[Flags]
public enum IFILTER_INIT : uint
{
NONE = 0,
CANON_PARAGRAPHS = 1,
HARD_LINE_BREAKS = 2,
CANON_HYPHENS = 4,
CANON_SPACES = 8,
APPLY_INDEX_ATTRIBUTES = 16,
APPLY_CRAWL_ATTRIBUTES = 256,
APPLY_OTHER_ATTRIBUTES = 32,
INDEXING_ONLY = 64,
SEARCH_LINKS = 128,
FILTER_OWNED_VALUE_OK = 512
}
public enum CHUNK_BREAKTYPE
{
CHUNK_NO_BREAK = 0,
CHUNK_EOW = 1,
CHUNK_EOS = 2,
CHUNK_EOP = 3,
CHUNK_EOC = 4
}
[Flags]
public enum CHUNKSTATE
{
CHUNK_TEXT = 0x1,
CHUNK_VALUE = 0x2,
CHUNK_FILTER_OWNED_VALUE = 0x4
}
[StructLayout(LayoutKind.Sequential)]
public struct PROPSPEC
{
public uint ulKind;
public uint propid;
public IntPtr lpwstr;
}
[StructLayout(LayoutKind.Sequential)]
public struct FULLPROPSPEC
{
public Guid guidPropSet;
public PROPSPEC psProperty;
}
[StructLayout(LayoutKind.Sequential)]
public struct STAT_CHUNK
{
public uint idChunk;
[MarshalAs(UnmanagedType.U4)] public CHUNK_BREAKTYPE breakType;
[MarshalAs(UnmanagedType.U4)] public CHUNKSTATE flags;
public uint locale;
[MarshalAs(UnmanagedType.Struct)] public FULLPROPSPEC attribute;
public uint idChunkSource;
public uint cwcStartSource;
public uint cwcLenSource;
}
[StructLayout(LayoutKind.Sequential)]
public struct FILTERREGION
{
public uint idChunk;
public uint cwcStart;
public uint cwcExtent;
}
[ComImport]
[Guid("89BCB740-6119-101A-BCB7-00DD010655AF")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IFilter
{
[PreserveSig]
int Init([MarshalAs(UnmanagedType.U4)] IFILTER_INIT grfFlags, uint cAttributes, [MarshalAs(UnmanagedType.LPArray, SizeParamIndex=1)] FULLPROPSPEC[] aAttributes, ref uint pdwFlags);
[PreserveSig]
int GetChunk(out STAT_CHUNK pStat);
[PreserveSig]
int GetText(ref uint pcwcBuffer, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder buffer);
void GetValue(ref UIntPtr ppPropValue);
void BindRegion([MarshalAs(UnmanagedType.Struct)] FILTERREGION origPos, ref Guid riid, ref UIntPtr ppunk);
}
[ComImport]
[Guid("f07f3920-7b8c-11cf-9be8-00aa004b9986")]
public class CFilter
{
}
public class IFilterConstants
{
public const uint PID_STG_DIRECTORY = 0x00000002;
public const uint PID_STG_CLASSID = 0x00000003;
public const uint PID_STG_STORAGETYPE = 0x00000004;
public const uint PID_STG_VOLUME_ID = 0x00000005;
public const uint PID_STG_PARENT_WORKID = 0x00000006;
public const uint PID_STG_SECONDARYSTORE = 0x00000007;
public const uint PID_STG_FILEINDEX = 0x00000008;
public const uint PID_STG_LASTCHANGEUSN = 0x00000009;
public const uint PID_STG_NAME = 0x0000000a;
public const uint PID_STG_PATH = 0x0000000b;
public const uint PID_STG_SIZE = 0x0000000c;
public const uint PID_STG_ATTRIBUTES = 0x0000000d;
public const uint PID_STG_WRITETIME = 0x0000000e;
public const uint PID_STG_CREATETIME = 0x0000000f;
public const uint PID_STG_ACCESSTIME = 0x00000010;
public const uint PID_STG_CHANGETIME = 0x00000011;
public const uint PID_STG_CONTENTS = 0x00000013;
public const uint PID_STG_SHORTNAME = 0x00000014;
public const int FILTER_E_END_OF_CHUNKS = (unchecked((int) 0x80041700));
public const int FILTER_E_NO_MORE_TEXT = (unchecked((int) 0x80041701));
public const int FILTER_E_NO_MORE_VALUES = (unchecked((int) 0x80041702));
public const int FILTER_E_NO_TEXT = (unchecked((int) 0x80041705));
public const int FILTER_E_NO_VALUES = (unchecked((int) 0x80041706));
public const int FILTER_S_LAST_TEXT = (unchecked((int) 0x00041709));
}
///
/// IFilter return codes
///
public enum IFilterReturnCodes : uint
{
///
/// Success
///
S_OK = 0,
///
/// The function was denied access to the filter file.
///
E_ACCESSDENIED = 0x80070005,
///
/// The function encountered an invalid handle, probably due to a low-memory situation.
///
E_HANDLE = 0x80070006,
///
/// The function received an invalid parameter.
///
E_INVALIDARG = 0x80070057,
///
/// Out of memory
///
E_OUTOFMEMORY = 0x8007000E,
///
/// Not implemented
///
E_NOTIMPL = 0x80004001,
///
/// Unknown error
///
E_FAIL = 0x80000008,
///
/// File not filtered due to password protection
///
FILTER_E_PASSWORD = 0x8004170B,
///
/// The document format is not recognised by the filter
///
FILTER_E_UNKNOWNFORMAT = 0x8004170C,
///
/// No text in current chunk
///
FILTER_E_NO_TEXT = 0x80041705,
///
/// No more chunks of text available in object
///
FILTER_E_END_OF_CHUNKS = 0x80041700,
///
/// No more text available in chunk
///
FILTER_E_NO_MORE_TEXT = 0x80041701,
///
/// No more property values available in chunk
///
FILTER_E_NO_MORE_VALUES = 0x80041702,
///
/// Unable to access object
///
FILTER_E_ACCESS = 0x80041703,
///
/// Moniker doesn't cover entire region
///
FILTER_W_MONIKER_CLIPPED = 0x00041704,
///
/// Unable to bind IFilter for embedded object
///
FILTER_E_EMBEDDING_UNAVAILABLE = 0x80041707,
///
/// Unable to bind IFilter for linked object
///
FILTER_E_LINK_UNAVAILABLE = 0x80041708,
///
/// This is the last text in the current chunk
///
FILTER_S_LAST_TEXT = 0x00041709,
///
/// This is the last value in the current chunk
///
FILTER_S_LAST_VALUES = 0x0004170A
}
///
/// Convenience class which provides static methods to extract text from files using installed IFilters
///
public class DefaultParser
{
public DefaultParser()
{
}
[DllImport("query.dll", CharSet = CharSet.Unicode)]
private extern static int LoadIFilter(string pwcsPath, [MarshalAs(UnmanagedType.IUnknown)] object pUnkOuter, ref IFilter ppIUnk);
private static IFilter loadIFilter(string filename)
{
object outer = null;
IFilter filter = null;
// Try to load the corresponding IFilter
int resultLoad = LoadIFilter(filename, outer, ref filter);
if (resultLoad != (int) IFilterReturnCodes.S_OK)
{
return null;
}
return filter;
}
public static bool IsParseable(string filename)
{
return loadIFilter(filename) != null;
}
public static string Extract(string path)
{
StringBuilder sb = new StringBuilder();
IFilter filter = null;
try
{
filter = loadIFilter(path);
if (filter == null)
return String.Empty;
uint i = 0;
STAT_CHUNK ps = new STAT_CHUNK();
IFILTER_INIT iflags =
IFILTER_INIT.CANON_HYPHENS |
IFILTER_INIT.CANON_PARAGRAPHS |
IFILTER_INIT.CANON_SPACES |
IFILTER_INIT.APPLY_CRAWL_ATTRIBUTES |
IFILTER_INIT.APPLY_INDEX_ATTRIBUTES |
IFILTER_INIT.APPLY_OTHER_ATTRIBUTES |
IFILTER_INIT.HARD_LINE_BREAKS |
IFILTER_INIT.SEARCH_LINKS |
IFILTER_INIT.FILTER_OWNED_VALUE_OK;
if (filter.Init(iflags, 0, null, ref i) != (int) IFilterReturnCodes.S_OK)
throw new Exception("Problem initializing an IFilter for:\n" + path + " \n\n");
while (filter.GetChunk(out ps) == (int) (IFilterReturnCodes.S_OK))
{
if (ps.flags == CHUNKSTATE.CHUNK_TEXT)
{
IFilterReturnCodes scode = 0;
while (scode == IFilterReturnCodes.S_OK || scode == IFilterReturnCodes.FILTER_S_LAST_TEXT)
{
uint pcwcBuffer = 65536;
System.Text.StringBuilder sbBuffer = new System.Text.StringBuilder((int)pcwcBuffer);
scode = (IFilterReturnCodes) filter.GetText(ref pcwcBuffer, sbBuffer);
if (pcwcBuffer > 0 && sbBuffer.Length > 0)
{
if (sbBuffer.Length < pcwcBuffer) // Should never happen, but it happens !
pcwcBuffer = (uint)sbBuffer.Length;
sb.Append(sbBuffer.ToString(0, (int) pcwcBuffer));
sb.Append(" "); // "\r\n"
}
}
}
}
}
finally
{
if (filter != null) {
Marshal.ReleaseComObject (filter);
System.GC.Collect();
System.GC.WaitForPendingFinalizers();
}
}
return sb.ToString();
}
}
}
目前,这似乎是在Windows服务器上使用.NET平台从文档中提取文本的最佳方式.谢谢大家的帮助.
更新 - 2011年3月8日
虽然我仍然认为ifilters是一个很好的方法,但我认为如果你想使用.NET中的Lucene索引文档,一个非常好的选择就是使用Solr.当我第一次开始研究这个主题时,我从未听说过Solr.所以,对于那些没有这两者的人来说,Solr是一个独立的搜索服务,在Lucene之上用Java编写.我们的想法是,你可以在防火墙的机器上启动Solr,并通过HTTP从.NET应用程序与它进行通信.Solr真的像服务一样写,可以做Lucene可以做的一切,(包括使用来自.PDF,.XLS,.DOC,.PPT等的Tika提取文本),然后是一些.Solr似乎也有一个非常活跃的社区,这是我对Lucene.NET不确定的一件事.
您还可以查看ifilters - 如果您搜索asp.net ifilters,有许多资源:
当然,如果要将其分发到客户端系统,则会增加麻烦,因为您需要将ifilter包含在您的发行版中,并将其与您的应用程序一起安装到他们的计算机上,否则他们将无法从任何文件中提取文本他们没有ifilters.
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