文件的分割与合并

package service;
import service.oss.FileUtil;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.io.SequenceInputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Vector;
 
public class SplitFile {
    //文件的路径
    private String filePath;
    //文件名
    private String fileName;
    //文件大小
    private long length;
    //块数
    private int size;
    //每块的大小
    private long blockSize;
    //分割后的存放目录
    private String destBlockPath;
    //每块的名称
    private List<String> blockPath;
    
    public SplitFile(){
        blockPath = new ArrayList<String>();
    }
    public SplitFile(String filePath,String destBlockPath){
        this(filePath,destBlockPath,1024);        
    }
    public SplitFile(String filePath,String destBlockPath,long blockSize){
        this();
        this.filePath= filePath;
        this.destBlockPath =destBlockPath;
        this.blockSize=blockSize;
        init();
    }
    
    /**
     * 初始化操作 计算 块数、确定文件名
     */
    public void init(){
        File src =null;
        //健壮性
        if(null==filePath ||!(((src=new File(filePath)).exists()))){
            return;
        }
        if(src.isDirectory()){
            return ;
        }
        //文件名
        this.fileName =src.getName();
        
        //计算块数 实际大小 与每块大小
        this.length = src.length();
        //修正 每块大小
        if(this.blockSize>length){
            this.blockSize =length;
        }
        //确定块数        
        size= (int)(Math.ceil(length*1.0/this.blockSize));
        //确定文件的路径
        initPathName();
    }
    
    private void initPathName(){
        for(int i=0;i<size;i++){
            this.blockPath.add(destBlockPath+"/"+this.fileName+".part"+i);
        }
    }
    
    /**
     * 文件的分割
     * 0)、第几块
     * 1、起始位置
     * 2、实际大小
     * @param
     */
    public void split(){    
        long beginPos =0;  //起始点
        long actualBlockSize =blockSize; //实际大小        
        //计算所有块的大小、位置、索引
        for(int i=0;i<size;i++){
            if(i==size-1){ //最后一块
                actualBlockSize =this.length-beginPos;
            }            
            spiltDetail(i,beginPos,actualBlockSize);
            beginPos+=actualBlockSize; //本次的终点，下一次的起点
        }
        
    }
    /**
     * 文件的分割 输入 输出
     * 文件拷贝
     * @param idx 第几块
     * @param beginPos 起始点
     * @param actualBlockSize 实际大小
     */
    private void spiltDetail(int idx,long beginPos,long actualBlockSize){
        //1、创建源
        File src = new File(this.filePath);  //源文件
        File dest = new File(this.blockPath.get(idx)); //目标文件
        //2、选择流
        RandomAccessFile raf = null;  //输入流
        BufferedOutputStream bos=null; //输出流
        try {
            raf=new RandomAccessFile(src,"r");
            bos =new BufferedOutputStream(new FileOutputStream(dest));
            //读取文件
            raf.seek(beginPos);
            //缓冲区
            byte[] flush = new byte[1024];
            //接收长度
            int len =0;
            while(-1!=(len=raf.read(flush))){                
                if(actualBlockSize-len>=0){ //查看是否足够
                    //写出
                    bos.write(flush, 0, len);
                    actualBlockSize-=len; //剩余量
                }else{ //写出最后一次的剩余量
                    bos.write(flush, 0, (int)actualBlockSize);
                    break;
                }
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            FileUtil.close(bos,raf);
        }
    }
    /**
     * 文件的合并
     */
    public void merge(String destPath){
        //创建源
        File dest =new File(destPath);
        //选择流
        BufferedOutputStream bos=null; //输出流
        SequenceInputStream sis =null ;//输入流
        //创建一个容器
        Vector<InputStream> vi = new Vector<InputStream>();        
        try {
            for (int i = 0; i < this.blockPath.size(); i++) {
                vi.add(new BufferedInputStream(new FileInputStream(new File(this.blockPath.get(i)))));
            }    
            bos =new BufferedOutputStream(new FileOutputStream(dest,true)); //追加
            sis=new SequenceInputStream(vi.elements());            
            //缓冲区
            byte[] flush = new byte[1024];
            //接收长度
            int len =0;
            while(-1!=(len=sis.read(flush))){                        
                bos.write(flush, 0, len);
            }
            bos.flush();
            FileUtil.close(sis);
        } catch (Exception e) {
        }finally{
            FileUtil.close(bos);
        }        
    }
    /**
     * @param args
     */
    public static void main(String[] args) {
        //1024 * 30 表示按照每块30Kb大小分割
        SplitFile split = new SplitFile("C:\Users\Spring\Desktop\二期(后台)需求20191209(1).doc","C:/123/",1024);
        
        System.out.println(split.size);
//
//        split.split();
        
        split.merge("C:/123/logFile.doc");
        
    }
 
}