<dependency>      <groupId>commons-codec</groupId>      <artifactId>commons-codec</artifactId>      <version>1.6</version>    </dependency>

import org.apache.commons.codec.binary.Base64;import java.io.*;import java.util.HashMap;import java.util.Map;/** * Created by Liwj on 2016/8/23. */public class FileSplit {    /**     * 分割     * @param fileName 文件路径     * @param Number 分块文件个数     * @throws Exception     */    public void splitByNumber(String fileName,int Number) throws Exception{        File oldFile=new File(fileName);        BufferedInputStream in=new BufferedInputStream(new FileInputStream(oldFile));        String file=encode(in);        int length=file.length();        System.out.println("字符串长度："+length);        int size=length/Number;        int start=0,end=size;        BufferedOutputStream out=null;        File newFile=null;        String str_temp=null;        for(int i=0;i<Number-1;i++){            str_temp=i+" "+oldFile.getName()+"\n";            str_temp+=file.substring(start,end);            newFile=new File("E:\\result\\"+randNumber()+".file");            out=new BufferedOutputStream(new FileOutputStream(newFile));            out.write(str_temp.getBytes());            out.close();            start+=size;            end+=size;        }        str_temp=Number-1+" "+oldFile.getName()+"\n";        str_temp+=file.substring(start);        newFile=new File("E:\\result\\"+randNumber()+".file");        out=new BufferedOutputStream(new FileOutputStream(newFile));        out.write(str_temp.getBytes());        out.close();        return;    }    /**     * 文件合并     * @param path     * @throws Exception     */    public void mergeByName(String path) throws Exception{        File file=new File(path);        File list[]=file.listFiles();        Map<String,String> map=new HashMap<String, String>();        String newFileName=null;        for(File f:list){            BufferedReader reader=new BufferedReader(new InputStreamReader(new FileInputStream(f)));            String str_head=reader.readLine();            String id=str_head.substring(0,str_head.indexOf(" "));            newFileName=str_head.substring(str_head.indexOf(" ")+1);            map.put(id,f.getAbsolutePath());            reader.close();        }        StringBuffer stringBuffer=new StringBuffer();        for(int i=0;i<list.length;i++){            File f=new File(map.get(String.valueOf(i)));            BufferedReader reader=new BufferedReader(new InputStreamReader(new FileInputStream(f)));            reader.readLine();            String temp=null;            while ((temp=reader.readLine())!=null){                stringBuffer.append(temp);            }            reader.close();        }        BufferedOutputStream out=new BufferedOutputStream(new FileOutputStream("E:\\answer\\"+newFileName));        out.write(decode(stringBuffer.toString()));        out.close();    }    /**     * 编码     * @param in     * @return     * @throws IOException     */    public String encode(InputStream in) throws IOException{        byte[] data = http://www.mamicode.com/new byte[in.available()];        in.read(data);        return Base64.encodeBase64String(data);    }    /**     * 解码     * @param base64Str     * @return     * @throws IOException     */    public byte[] decode(String base64Str)throws IOException{        return Base64.decodeBase64(base64Str);    }    /**     * 随机数     * @return     */    public String randNumber(){        double number=Math.random();        String str= String.valueOf(number);        str=str.replace(".","");        return str;    }    public static void main(String[] args){        try {            //分块            //new FileSplit().splitByNumber("E:\\20160824134947.jpg",10);            //合并            //new FileSplit().mergeByName("E:\\result\\");        }catch (Exception e){            e.printStackTrace();        }    }}