从一个流中查找指定数组

import java.io.InputStream;


public class SeekInputStream 
{
	
	/**
	 * 在流中查找,不适合查找全0数组,by samyou
	 * @param in
	 * @param key
	 * @return
	 */
	public static int seekBytes(InputStream in,byte[] key)
	{
		int lastSeekEnd = 0;
		int result = -1;
		byte buff[] = new byte[1000];
		if(key.length > buff.length)
		{
			return -1;
		}
		try 
		{
			in.read(buff);
			do{
				result = normalSeek(buff, key);
				if(result >= 0)
				{
					break;
				}
				System.arraycopy(buff, buff.length-key.length, buff, 0, key.length);
				lastSeekEnd+=buff.length-key.length;
			}
			while( in.read(buff, key.length, buff.length-key.length) >0 );
			
		} 
		catch (Exception e) 
		{
			e.printStackTrace();
			try {
				in.close();
			} catch (Exception e2) {
			}
			return -1;
		}
		try {
			in.close();
		} catch (Exception e2) {
		}
		return result+lastSeekEnd;
	}
	
	
	
	
	/**
	 KMP查找算法
	 在一块buff中找
	 */
	private static int normalSeek(byte[] buff,byte[] key)
	{
		for(int i=0;i<buff.length -key.length;i++)
		{
			boolean seekSuccess = true;
			for(int j=0;j<key.length;j++)
			{
				if(buff[i+j] != key[j])
				{
					seekSuccess  =false;
					break;
				}
			}
			if(seekSuccess)
			{
				return i;
			}
		}
		return -1;
	}

}