二进制文件二分查找算法

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package com.xxx.xxx.query.version2;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.xxx.xxx.decode.MetaData;
import com.xxx.xxx.utils.DateFormatUtil;


public abstract class DataReader {
	protected static Log log = LogFactory.getLog(DataReader.class);
	
	
	protected static final int BUF_SIZE = 1024 * 4;
	
	protected static final long MIN = 0L;
	
	protected static final long MAX = 99999999999999L;
	
	static final ThreadLocal<SimpleDateFormat> TL_DATE_FORMAT = DateFormatUtil.threadLocalDateFormat("yyyyMMddHHmmss");
	
	public static long time_t2tick(long time_t, int clctDate){
		long tick = 0L;		
		Date date = new Date(time_t * 1000);		
		DateFormat df = TL_DATE_FORMAT.get();		
		String str = df.format(date);					
		tick = Long.parseLong(str);		
		int clctYear = clctDate/10000;
		int year = (int) (tick/10000000000L);
		
	//	System.out.println(clctYear + " " + year);
		if(((clctYear - year) > 1)||((clctYear - year) < -1)){
			long tail = tick%10000000000L;
			long head = clctYear * 10000000000L;
			tick = head + tail;
		//	System.out.println("tick " + tick);
		}
		return tick;
	}
	
	public abstract int getDataBuffSize();
	
	public MetaData readTailRecord(String fileName, int date){
		MetaData data = null;
		int dataBuffSize = this.getDataBuffSize();
		if(null != fileName && fileName.length() > 0 && dataBuffSize > 0){
			File file = new File(fileName);
			if(file.exists()){
				long len = file.length();
				long pos = len - dataBuffSize;
				data = readSingleData(fileName, pos, date);
			}			
		}
		return data;
	}
	
	public MetaData readRecordByTick(String fileName, long tick, int date){
		return binarySearchTick(fileName, tick, this.getDataBuffSize(), date);
	}
	
	protected MetaData readSingleData(String fileName, long pos, int date) {
		MetaData data = null;
		int dataBuffSize = this.getDataBuffSize();
		if(null != fileName && fileName.length() > 0 && pos >= 0 && dataBuffSize > 0){
			try {
				byte[] buf = readBuf(fileName, pos, pos + dataBuffSize, dataBuffSize);
				if(null != buf && buf.length == dataBuffSize){
					@SuppressWarnings("unchecked")
					List<MetaData> list = (List<MetaData>) this.decodeBody(buf, date);
					if(null != list && list.size() > 0){
						data = list.get(list.size() - 1);
					}
				}
			} catch (Exception e) {
				System.out.println(e);
			}
		}
		return data;
	}
		
	protected MetaData binarySearchTick(String fileName, long tick, int dataSize, int date) {
		MetaData data = null;	
				
		if(null != fileName && fileName.length() > 0 && tick > 0 && dataSize > 0){
			File file = new File(fileName);		
			if(file.exists()){			
				int low = 0;
				int high = (int)(file.length()/dataSize);
				int hit = 0;

				while(low <= high){
					int mid = (low + high) / 2;
					int midOffSet = mid * dataSize;
										
					MetaData current = readSingleData(fileName, midOffSet, date);					
					if(null != current){						
						long midTick = current.getTick();
												
						if(midTick < tick){
							low = mid + 1;
						}						
						else if(midTick > tick){
							high = mid - 1;
						}						
						else{
							hit = mid;
							data = current;
							break;
						}						
					}
					hit = low - 1;	
				}
						
				if(null == data && hit > 0){

				//	System.out.println("readSingleData " + fileName+ " " + hit * dataSize);
					if(hit * dataSize == file.length())
					{
						hit--;
					}
					data = readSingleData(fileName, hit * dataSize, date);	
			
				}
			}	
		}	
		return data;
	}
	
	protected final static byte[] readBuf(String filePath, long beginPos, long endPos, int buffSize){
		byte[] buf = null;
		File file = null;
		RandomAccessFile raf = null;

		if(null != filePath && filePath.length() > 0 && beginPos >= 0 && beginPos < endPos && buffSize > 0){
			buf = new byte[buffSize];
			try {
				file = new File(filePath);
				if(file.exists()){
					raf = new RandomAccessFile(file, "r");
					long size = raf.length();
					if(endPos <= size){
						raf.seek(beginPos);
						raf.read(buf);
					}
				}					
			} catch (Throwable e) {
				System.out.println(e);
			} finally {
				if (null != raf){
					try {
						raf.close();
					} catch (IOException e) {
					}
				}					
			}
		}
		return buf;
	}
	
	protected List<? extends MetaData> decodeBody(byte[] buf, int date) throws Exception{
		return this.decodeBody(buf, MIN, MAX, date);
	}

	protected abstract List<? extends MetaData> decodeBody(byte[] buf, long beginTime, long endTime, int date) throws Exception;
		
	protected final static byte[] intToByte2(int n) {
		byte[] bytes = new byte[2];
		for (int i = 0; i < 2; i++) {
			bytes[i] = (byte) (n % 256);
			n = n >> 8;
		}
		return bytes;
	}

	protected final static byte[] intToByte4(long n) {
		byte[] bytes = new byte[4];
		for (int i = 0; i < 4; i++) {
			bytes[i] = (byte) (n % 256);
			n = n >> 8;
		}
		return bytes;
	}

	protected final static byte[] longToByte8(long n) {
		byte[] bytes = new byte[8];
		for (int i = 0; i < 8; i++) {
			bytes[i] = (byte) (n % 256);
			n = n >> 8;
		}
		return bytes;
	}

	protected final static short byte1ToShort(byte b) {
		short n = 0;
		if (b < 0) {
			n = (short) (256 + b);
		} else {
			n = b;
		}
		return n;
	}

	protected final static int byte1ToInt(byte bt) {
		int n = 0;

		n = bt;
		if (bt < 0)
			n += 256;
		return n;
	}

	protected final static int byte2ToInt(byte[] buf, int start) {
		int n = 0;
		if (null != buf) {
			for (int i = 1; i >= 0; i--) {
				n <<= 8;
				n |= (buf[start + i] & 0x00ff);
			}
		}
		return n;
	}

	protected final static long byte8ToLong(byte[] buf, int start) {
		long n = 0;
		try {
			if (null != buf) {
				for (int i = 7; i >= 0; i--) {
					n <<= 8;
					n |= (buf[start + i] & 0x000000ff);
				}
			}
		} catch (Exception e) {
			log.error(e);
		}
		return n;
	}

	protected final static int byte4ToInt(byte[] buf, int start) {
		int n = 0;
		try {
			if (null != buf) {
				for (int i = 3; i >= 0; i--) {
					n <<= 8;
					n |= (buf[start + i] & 0x000000ff);
				}
			}
		} catch (Exception e) {
			log.error(e);
		}
		return n;
	}
}

package com.xxx.xxx.decode;

public abstract class MetaData
{
	public long getTick()
	{
		return tick;
	}

	public void setTick(long tick)
	{
		this.tick = tick;
	}
	

	
	protected long tick;
}

package com.xxx.xxx.utils;

import java.text.SimpleDateFormat;
import java.util.Locale;
import java.util.TimeZone;


public class DateFormatUtil {
	
	
	
	private static final String GMT_TIME_ZONE = "GMT+8:00".intern();
	
    public static ThreadLocal<SimpleDateFormat> threadLocalDateFormat(final String pattern) 
    {
        ThreadLocal<SimpleDateFormat> tl = new ThreadLocal<SimpleDateFormat>() {
            protected SimpleDateFormat initialValue() {
                SimpleDateFormat df = new SimpleDateFormat(pattern, Locale.ENGLISH);
                df.setTimeZone(TimeZone.getTimeZone(DateFormatUtil.GMT_TIME_ZONE));
                return df;
            }
        };
        return tl;
    }
    public static ThreadLocal<SimpleDateFormat> threadLocalDateFormat
    (final String pattern, final TimeZone time_zone) 
    {
        ThreadLocal<SimpleDateFormat> tl = new ThreadLocal<SimpleDateFormat>() 
        {
            protected SimpleDateFormat initialValue() {           	                       	
                SimpleDateFormat df = new SimpleDateFormat(pattern, Locale.ENGLISH);
                df.setTimeZone(time_zone);
                return df;
            }
        };
        return tl;
    }
}

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