用java分割与合并文件的一个简单示例

转载： http://hi.baidu.com/triceratops/blog

import java.io.*;

public class SplitAndCombineFile{
private byte[] buffer = new byte[1024];
private int current;

public void split(File file, long threshold) throws IOException{ 
   long fileSize = file.length();
   int fileFragmentCount = (int)(fileSize/threshold+1);
   long accumulate;
   String filePath = file.getAbsolutePath();
   FileInputStream fis = new FileInputStream(file);
   FileOutputStream fos;
   for(int i=0;i<fileFragmentCount;i++){
    fos = new FileOutputStream(new File(filePath+".part"+(i+1))); 
    accumulate = 0;
    while((current=fis.read(buffer,0,1024))!=-1){
     accumulate+=current;
     fos.write(buffer,0,current);
     fos.flush();
     if(accumulate>=threshold)
      break; 
    }
    fos.close();
   }  
}

public void combine(File targetFile, File partFileFolder) throws IOException{
    if(partFileFolder.isFile())
     throw new IOException("\""+partFileFolder+"\" is not a file folder!");
   
    FileOutputStream fos = new FileOutputStream(targetFile);
    FileInputStream fis;
    File[] partFiles = partFileFolder.listFiles();
    for(int i=0;i<partFiles.length;i++){
     fis = new FileInputStream(partFiles[i]);
     while((current=fis.read(buffer,0,1024))!=-1){
      fos.write(buffer,0,current);
      fos.flush();
     }
    }
    fos.close();
}
}