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perBlockSize perPartSize=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path if (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0 System.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) { } } }
时间: 2024-10-10 04:37:10