JAVA IO（5）使用序列流进行文件切割和合并

import java.io.*;
import java.util.*;

public class Main{
     /* 文件切割  */
     private static final int SIZE = 1024*1024;
     
     public static void splitFile(File file) throws IOException {
         
         FileInputStream fis = new FileInputStream(file);
         byte[] buffer = new byte[SIZE]; //切成n块SIZE大小
         FileOutputStream fos = null;
         int len = 0;
         int cnt = 1;
         
         /*使用properties记录切割文件产生的个数和被切割文件的名称，方便合并时使用 */
         Properties prop = new Properties();
         
         File partDir = new File("C:\\partFiles");
         if(!partDir.exists())
              partDir.mkdir();
         while((len = fis.read(buffer)) != -1) {
              fos = new FileOutputStream(new File(partDir,(cnt++)+".part")); //自定义碎片文件后缀.part
              fos.write(buffer,0,len);
              fos.close();
         }
         
         //将切割文件信息保存在Properties中
         prop.setProperty("partNum", cnt+"");
         prop.setProperty("fileName", file.getName());
         fos = new FileOutputStream(new File(partDir,(cnt++)+".properties"));
         prop.store(fos, "");//将properties集合中的信息存储到文件中。
         fos.close();
         fis.close();
     }
     
     /* 合并碎片文件 */
     public static void mergeFile(File dir) throws IOException {
         
         File[] files = dir.listFiles(new SuffixFilter(".properties"));
         if(files.length != 1)
              throw new RuntimeException(dir+"配置文件不存在或配置文件重复");
         
         //记录配置文件信息
         File confile = files[0];
         
         //获取该文件信息
         Properties prop = new Properties();
         FileInputStream fis = new FileInputStream(confile);
         prop.load(fis);
         
         //获取prop中的信息
         String fileName = prop.getProperty("filename");
         int cnt = Integer.parseInt(prop.getProperty("partNum"));
         
         //获取该文件夹下所有碎片，统计个数
         File[] partFiles = dir.listFiles(new SuffixFilter(".part"));
         if(partFiles.length != (cnt-1))
              throw new RuntimeException("碎片个数不对，应为"+cnt+"个");
         
         //添加集合
         ArrayList<FileInputStream> a1 = new ArrayList<FileInputStream>();
         for(int i=0; i<partFiles.length; i++)
              a1.add(new FileInputStream(files[i]));
         
         Enumeration<FileInputStream> en = Collections.enumeration(a1);
         SequenceInputStream sis = new SequenceInputStream(en);
         FileOutputStream fos = new FileOutputStream(new File(dir,fileName));
         
         byte[] buffer = new byte[1024*1024];
         int len = 0;
         
         while((len = sis.read(buffer)) != -1) {
              fos.write(buffer,0,len);
         }
         fos.close();
         sis.close();
     }
     
     public static void main(String[] args) throws IOException {
         splitFile(new File("D:\\demo4.txt"));
         mergeFile(new File("C:\\partFiles"));
         
     }    
}



class SuffixFilter implements FilenameFilter {
    
    private String suffix;
    
    public SuffixFilter(String suffix) {
        super();
        this.suffix = suffix;
    }

    @Override
    public boolean accept(File dir, String name) {
        
        return name.endsWith(suffix);
    }

}