我正在试图删除以下HTML代码的标题：
using System;
using System.Threading;
using System.Runtime.InteropServices;
using System.Collections;
using System.Linq;
namespace LowLevelAudio
{
internal class WaveOutHelper
{
public static void Try(int err)
{
if (err != WaveNative.MMSYSERR_NOERROR)
throw new Exception(err.ToString());
}
}
public delegate void BufferFillEventHandler(IntPtr data, int size);
public class WaveOutBuffer : IDisposable
{
private AutoResetEvent m_PlayEvent = new AutoResetEvent(false);
private IntPtr m_WaveOut;
private int m_buffersize;
private static byte[] m_samples;
private static double[] m_fftsamples;
private WaveNative.WaveHdr m_Header;
private byte[] m_HeaderData;
private GCHandle m_HeaderHandle;
private GCHandle m_HeaderDataHandle;
private WaveFormat m_waveformat;
private double[] m_fftOccurances;
private double[] m_fftHertzlist;
private bool m_Playing;
public int ID
{
get; set;
}
internal static void WaveOutProc(IntPtr hdrvr, int uMsg, int dwUser, ref WaveNative.WaveHdr wavhdr, int dwParam2)
{
if (uMsg == WaveNative.MM_WOM_DONE)
{
try
{
GCHandle h = (GCHandle)wavhdr.dwUser;
WaveOutBuffer buf = (WaveOutBuffer)h.Target;
buf.OnPlayCompleted();
}
catch(Exception ex)
{
Console.WriteLine("Exception: " + ex.Message);
}
}
}
public WaveOutBuffer(IntPtr waveOutHandle, int size, WaveFormat format)
{
m_WaveOut = waveOutHandle;
m_waveformat = format;
m_HeaderHandle = GCHandle.Alloc(m_Header, GCHandleType.Pinned);
m_Header.dwUser = (IntPtr)GCHandle.Alloc(this);
m_HeaderData = new byte[size];
m_HeaderDataHandle = GCHandle.Alloc(m_HeaderData, GCHandleType.Pinned);
m_Header.lpData = m_HeaderDataHandle.AddrOfPinnedObject();
m_Header.dwBufferLength = size;
m_buffersize = size;
m_samples = new byte[m_buffersize];
WaveOutHelper.Try(WaveNative.waveOutPrepareHeader(m_WaveOut, ref m_Header, Marshal.SizeOf(m_Header)));
}
~WaveOutBuffer()
{
Dispose();
}
public int Size
{
get { return m_Header.dwBufferLength; }
}
public IntPtr Data
{
get { return m_Header.lpData; }
}
public void Dispose()
{
if (m_Header.lpData != IntPtr.Zero)
{
WaveNative.waveOutUnprepareHeader(m_WaveOut, ref m_Header, Marshal.SizeOf(m_Header));
m_HeaderHandle.Free();
m_Header.lpData = IntPtr.Zero;
}
m_PlayEvent.Close();
if (m_HeaderDataHandle.IsAllocated)
m_HeaderDataHandle.Free();
}
public bool Play()
{
lock(this) // works, but has to be fine tuned... (to do)
{
m_PlayEvent.Reset();
m_Playing = WaveNative.waveOutWrite(m_WaveOut, ref m_Header, Marshal.SizeOf(m_Header)) == WaveNative.MMSYSERR_NOERROR;
if (!m_Playing)
throw new Exception("test exception");
return m_Playing;
}
}
public void WaitForMe()
{
Console.WriteLine(this.ID + " WaitFor()");
if (m_Playing)
{
m_Playing = m_PlayEvent.WaitOne();
}
else
{
m_Playing = false;
}
}
public void OnPlayCompleted()
{
Console.WriteLine(this.ID + " OnCompleted()");
m_PlayEvent.Set();
m_Playing = false;
}
}
public class WaveOutPlayer : IDisposable
{
private IntPtr m_WaveOut;
private WaveOutBuffer[] m_bufferlist;
private Thread m_Thread;
private BufferFillEventHandler m_FillProc;
private bool m_Finished;
private byte m_zero;
private int m_buffercount = 0;
private int m_buffersize = 0;
private WaveFormat m_waveformat;
private WaveNative.WaveDelegate m_BufferProc = new WaveNative.WaveDelegate(WaveOutBuffer.WaveOutProc);
public static int DeviceCount
{
get { return WaveNative.waveOutGetNumDevs(); }
}
public WaveOutPlayer(int device, WaveFormat format, int bufferSize, BufferFillEventHandler fillProc)
{
m_zero = format.wBitsPerSample == 8 ? (byte)128 : (byte)0;
m_FillProc = fillProc;
m_buffercount = 2;
m_buffersize = bufferSize;
m_waveformat = format;
WaveOutHelper.Try(WaveNative.waveOutOpen(out m_WaveOut, device, format, m_BufferProc, 0, WaveNative.CALLBACK_FUNCTION));
AllocateBuffers(bufferSize, m_buffercount, format);
m_Thread = new Thread(new ThreadStart(ThreadProc));
m_Thread.Start();
}
~WaveOutPlayer()
{
Dispose();
}
public void Dispose()
{
if (m_Thread != null)
{
try
{
m_Finished = true;
if (m_WaveOut != IntPtr.Zero)
WaveNative.waveOutReset(m_WaveOut);
m_Thread.Join();
m_FillProc = null;
FreeBuffers();
if (m_WaveOut != IntPtr.Zero)
WaveNative.waveOutClose(m_WaveOut);
}
finally
{
m_Thread = null;
m_WaveOut = IntPtr.Zero;
}
}
}
private void ThreadProc()
{
WaveOutBuffer b0 = m_bufferlist[0];
WaveOutBuffer b1 = m_bufferlist[1];
MainForm form = Program.getUI();
bool s = true;
m_FillProc(b0.Data, b0.Size);
while (!m_Finished)
{
if (s)
{
Console.WriteLine("-------------------------");
Console.WriteLine("Playing b0, filling b1");
b0.Play();
m_FillProc(b1.Data, b1.Size);
form.paintEqualizer(b0);
Console.WriteLine("callng waitFor on b0");
b0.WaitForMe();
}
else
{
Console.WriteLine("-------------------------");
Console.WriteLine("Playing b1, filling b0");
b1.Play();
m_FillProc(b0.Data, b0.Size);
form.paintEqualizer(b1);
Console.WriteLine("callng waitFor on b1");
b1.WaitForMe();
}
s = !s;
}
}
private void AllocateBuffers(int bufferSize, int bufferCount, WaveFormat format)
{
FreeBuffers();
m_bufferlist = new WaveOutBuffer[m_buffercount];
if (bufferCount > 0)
{
for (int i = 0; i < m_buffercount; i++)
{
m_bufferlist[i] = new WaveOutBuffer(m_WaveOut, bufferSize, format);
m_bufferlist[i].ID = i;
}
}
}
private void FreeBuffers()
{
if (m_bufferlist != null)
{
foreach (WaveOutBuffer currentBuffer in m_bufferlist)
{
if (currentBuffer != null)
{
currentBuffer.Dispose();
}
}
}
}
}
}
我正在使用此代码：
<FONT COLOR=#5FA505><B>Claim:</B></FONT> Coed makes unintentionally risqué remark about professor's "little quizzies."
<BR><BR>
<CENTER><IMG SRC="/images/content-divider.gif"></CENTER>
并且我成功地从前面提到的html代码中提取了我想要的正确def parse_article(self, response):
for href in response.xpath('//font[b = "Claim:"]/following-sibling::text()'):
print href.extract()
值，但它也（在同一页面中具有类似结构的其他）中拉出了下面的html。我定义了我的Claim:，只需提取名为xpath()的{{1}}标记，那么为什么它也会引入下面的font？我该如何解决？我试过看看我是否只能获得下一个Claim:而不是所有这些，但这不起作用
Origins答案 0 :(得分：0)
我认为您的xpath缺少text()限定符（解释here）。它应该是：
'//font/[b/text()="Claim:"]/following-sibling::text()'
答案 1 :(得分：0)
following-sibling轴返回元素后面的所有兄弟节点。如果您只想要第一个兄弟，请尝试XPath表达式：
//font[b = "Claim:"]/following-sibling::text()[1]
或者，根据您的具体用例：
(//font[b = "Claim:"]/following-sibling::text())[1]