Java语言实现文件分割与合并

一：

题目：

写一个方法,将feige.exe文件分割为每份1MB大小的若干份(最后一份可以不满1MB),
存储在一个temp的文件夹中(每份文件名自己定义,例如1.temp 2.temp),
然后再写一个方法,将temp文件夹中的若干份合并为一个文件fg.exe

代码：

main

package com.ffyc.javaIO.zy.zy1;

import java.io.*;

public class T3 { 
    public static void main(String[] args) throws IOException {
        File file1 = new File("D:/feige.exe");
        resolve(file1);
        compound(file1);
    } 
}

分割

 
public static void resolve(File file) throws IOException {
    FileInputStream in = new FileInputStream(file);
    BufferedInputStream bin = new BufferedInputStream(in);
    File f = new File("D:/temp");
    if(!f.exists()){
        f.mkdir();
    }
    int size = 0;
    byte[] bytes = new byte[1024*1024];
    int i = 0;
    while ((size = bin.read(bytes)) != -1){
        i++;
        FileOutputStream out = new FileOutputStream("D:/temp/"+i+".temp");
        BufferedOutputStream bout = new BufferedOutputStream(out);
        bout.write(bytes, 0, size);
        bout.flush();
        bout.close();
    }
    bin.close();
}

合并

public static void compound(File file) throws IOException {
        FileOutputStream out = new FileOutputStream("D:/fg.exe");
        File f = new File("D:/temp");
        int num = f.list().length;
        for (int i = 1; i <= num; i++) {
            FileInputStream in = new FileInputStream("D:/temp/"+i+".temp");
            byte[] bytes = new byte[1024];
            int size = 0;
            while ((size = in.read(bytes)) != -1) {
                out.write(bytes, 0, size);
            }
            in.close();
        }
        out.close();
    }

运行

二：

题目：

完善文件分割,将1MB文件分多次读写

思路：

文件的大小 file.length 总共的字节数
每份的大小 1MB
总共有多少份 = 总共的字节数/每份大小+1
fori 知道输入多少个文件了
FileOutputStream out = new FileOutputStream("D:/temp/"+i+".temp");
int size = 0;
byte[] bytes = new byte[1024];
int i = 0;
while ( )

代码：

package com.ffyc.javaIO.zy.zy2;

import java.io.*;

public class T3 {
    public static void main(String[] args) throws IOException {
        File f = new File("D:/temp");
        if(!f.exists()){
            f.mkdir();
        }
        File file = new File("D:/feige.exe");
        FileInputStream in = new FileInputStream(file);
        //文件长度  字节数量
        long len = (file.length()%1024%1024)==0?(file.length()/1024/1024):(file.length()/1024/1024)+1;
        for (int i = 0; i < len; i++) {
            int sum = 0;
            int size = 0;
            byte[] bytes = new byte[1024];
            FileOutputStream out = new FileOutputStream("D:/temp/"+i+".temp");
            while ((size = in.read(bytes)) != -1){
                sum+=size;
                out.write(bytes,0,size);
                //记录有没有1mb
                if(sum>1024*1024){
                    break;
                }
            }
            out.close();
        }
        in.close();
    }
}