javase 数据流与文件分割合并

案例：对本地一张微信保存的图片进行分割和合并

package com.lx21;

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.SequenceInputStream;
import java.util.Enumeration;
import java.util.Vector;

public class FileDevisionMergeDemo {
	
	private static void division(File targetFile ,long cutsize) {
		if (targetFile==null) return;
		int num = targetFile.length()%cutsize==0?
				(int)(targetFile.length()/cutsize):(int)(targetFile.length()/cutsize+1);
		//构造输入流
		try {
			BufferedInputStream in  = new BufferedInputStream(new FileInputStream(targetFile));
			BufferedOutputStream out = null;
			
			byte[] bytes = null;
			int len = -1;
			int count = 0;//文件读取的次数
			for(int i = 0;i0&&(len=in.read(bytes))!=-1){
					out.write(bytes,0,len);
					out.flush();
					count--;
				}
				if(cutsize%1024!=0) {
					bytes = new byte[(int)cutsize%1024];
					len = in.read(bytes);
					out.write(bytes, 0, len);
					out.flush();
					out.close();
				}
			}
			in.close();
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	@SuppressWarnings("unused")
	private static void merge(Enumeration es) {
		//构造合并流
		SequenceInputStream sis = new SequenceInputStream(es);
		try {
			BufferedOutputStream bos =new BufferedOutputStream(new FileOutputStream("D:\javatest\wechat.png"));
			byte[] bytes = new byte[1024];
			int len = -1;
			while((len=sis.read(bytes))!=-1) {
				bos.write(bytes,0,len);
				bos.flush();
			}
			bos.close();
			sis.close();
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
	public static void main(String[] args) {
		File file = new File ("D:\javatest\20220102131730.jpg") ;
		division(file, 1024*1024);
		
		try {
			InputStream in1 =new FileInputStream(new File("D:\javatest1-temp-20220102131730.jpg"));
			InputStream in2 =new FileInputStream(new File("D:\javatest\javatest2-temp-20220102131730.jpg"));
			InputStream in3 =new FileInputStream(new File("D:\javatest\javatest3-temp-20220102131730.jpg"));
			InputStream in4 =new FileInputStream(new File("D:\javatest\javatest4-temp-20220102131730.jpg"));
			InputStream in5 =new FileInputStream(new File("D:\javatest\javatest5-temp-20220102131730.jpg"));
			InputStream in6 =new FileInputStream(new File("D:\javatest\javatest6-temp-20220102131730.jpg"));
			InputStream in7 =new FileInputStream(new File("D:\javatest\javatest7-temp-20220102131730.jpg"));
			InputStream in8 =new FileInputStream(new File("D:\javatest\javatest8-temp-20220102131730.jpg"));
			InputStream in9 =new FileInputStream(new File("D:\javatest\javatest9-temp-20220102131730.jpg"));
			InputStream in10 =new FileInputStream(new File("D:\javatest\javatest10-temp-20220102131730.jpg"));
			InputStream in11 =new FileInputStream(new File("D:\javatest\javatest11-temp-20220102131730.jpg"));
			InputStream in12 =new FileInputStream(new File("D:\javatest\javatest12-temp-20220102131730.jpg"));
			InputStream in13 =new FileInputStream(new File("D:\javatest\javatest13-temp-20220102131730.jpg"));
			InputStream in14 =new FileInputStream(new File("D:\javatest\javatest14-temp-20220102131730.jpg"));
			InputStream in15 =new FileInputStream(new File("D:\javatest\javatest15-temp-20220102131730.jpg"));
			Vector e = new Vector();
			e.add(in1);
			e.add(in2);
			e.add(in3);
			e.add(in4);
			e.add(in5);
			e.add(in6);
			e.add(in7);
			e.add(in8);
			e.add(in9);
			e.add(in10);
			e.add(in11);
			e.add(in12);
			e.add(in13);
			e.add(in14);
			e.add(in15);
			Enumeration es = e.elements();
			merge(es);
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
}