Java文件的拆分与合并(一)
package cn.com;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.RandomAccessFile;//文件的拆分和组合//步骤://1 依据源文件大小和每块的大小计算出块数//2 将每一块写到一个对应的文件public class FileSeparatorAndUnite {long rawFileSize;long blocksNumber;String rawFileName=null;String [] allPaths=null;public static void main(String[] args) { FileSeparatorAndUnite test=new FileSeparatorAndUnite(); //拆分文件 String [] allPaths=test.separatorFile("F:\\2.jpg", 1024*10); //组合文件 test.uniteFile(allPaths, "F:\\99.jpg");}/** * @param rawFilePath 待拆分文件的路径 * @param perBlockSize 拆分后每份的大小 * @return 各部分路径的数组集合 */private String[] separatorFile(String rawFilePath,long perBlockSize){File rawFile=new File(rawFilePath);rawFileName=rawFile.getName();rawFileSize=rawFile.length();blocksNumber=getBlocksNumber(rawFileSize,perBlockSize);allPaths=new String[(int)blocksNumber];if (blocksNumber==1) {perBlockSize=rawFileSize;}long perPartSize=0;long perPartBeginPosition=0;String perPartPath=null;for (int i = 1; i <=blocksNumber; i++) {if (i<blocksNumber) {//每一块的大小就为perBlockSizeperPartSize=perBlockSize;} else {//最后一块的大小为总大小-该块的起始位置 perPartSize=rawFileSize-perPartBeginPosition;}//得到每一块的pathif (blocksNumber==1) {perPartPath=rawFilePath+".bat";} else {perPartPath=getPerPartFilePath(rawFilePath, i);}//操作每一块//第一次调用时perPartBeginPosition当然为0System.out.println("该Block开始位置:perPartBeginPosition="+perPartBeginPosition);writePerPartToFile(rawFilePath, perPartPath, perPartSize, perPartBeginPosition); //计算每一块的在原文件中的起始位置.perPartBeginPosition=perPartBeginPosition+perPartSize;//保存每一块的路径allPaths[i-1]=perPartPath;System.out.println("该Block大小:perPartSize="+perPartSize);}return allPaths;}/** * @param rawFilePath 原文件路径 * @param perPartFilePath 每部分对应的路径 * @param blockSize 每部分的块大小 * @param beginPosition 每部分在原文件中的开始位置 * @return * * rafForReader.read(buffer, 0, everyTimeReadLen) * 表示:向buffer中读入everyTimeReadLen个字节 */public boolean writePerPartToFile(String rawFilePath,String perPartFilePath,long blockSize,long beginPosition){RandomAccessFile rafForReader=null;RandomAccessFile rafForWriter=null;boolean isContinueReading=true;//每次应该读取的字节数 int everyTimeReadLen=0;byte [] buffer=new byte[1024*8];try {rafForReader=new RandomAccessFile(rawFilePath, "r");rafForReader.seek(beginPosition);File perPartFile=new File(perPartFilePath);rafForWriter=new RandomAccessFile(perPartFile, "rw");//设置文件大小rafForWriter.setLength(blockSize);int writerOff=0;//设置第一次read()应该读取的字节if (blockSize>buffer.length) {everyTimeReadLen=buffer.length;}else {everyTimeReadLen=(int)blockSize;}while (rafForReader.read(buffer, 0, everyTimeReadLen)!=-1&&isContinueReading){ rafForWriter.seek(writerOff); writerOff+=everyTimeReadLen; rafForWriter.write(buffer, 0, everyTimeReadLen); //动态改变下次该读取的字节数 if (blockSize-writerOff>buffer.length) {everyTimeReadLen=buffer.length;}else {everyTimeReadLen=(int)blockSize-writerOff;} //读取完毕 if (everyTimeReadLen==0) {isContinueReading=false;}}rafForReader.close();rafForWriter.close();} catch (Exception e) {return false;}return true;}/** * @param rawFileSize 原文件大小 * @param perBlockSize 每块的大小 * @return 拆分后块数 */public long getBlocksNumber(long rawFileSize,long perBlockSize){if (rawFileSize<=perBlockSize) {return 1;} else { if (rawFileSize%perBlockSize==0) {return (rawFileSize/perBlockSize);} else { return (rawFileSize/perBlockSize)+1;}}}/** * @param rawFilePath 原文件路径 * @param blockNumer 当前块号码 * @return 当前块对应的路径 */public String getPerPartFilePath(String rawFilePath,int blockNumer){String perPartFilePath=rawFilePath+".part"+blockNumer;return perPartFilePath;}/** * @param partsPaths 各部分路径 * @param unitedFilePath 合并后文件路径 */public void uniteFile(String [] partsPaths,String unitedFilePath){try {File perPartFile=null;File unitedFile=new File(unitedFilePath);FileOutputStream fos=new FileOutputStream(unitedFile);FileInputStream fis=null;for (int i = 0; i < partsPaths.length; i++) {perPartFile=new File(partsPaths[i]);fis=new FileInputStream(perPartFile);byte [] buffer=new byte[1024*8];int len=0;while ((len=fis.read(buffer))!=-1) {fos.write(buffer, 0, len);}}fis.close();fos.close();} catch (Exception e) {}}}