Java将文件分割为多个子文件再将子文件合并成原始文件

import java.io.File;
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.OutputStream;
import java.io.FileOutputStream;
import java.util.Properties;
import java.util.Iterator;
import java.util.TreeSet;
import java.util.Set;

public class Test
{
	public static void main(String[] args) throws Exception
	{
		/*
		*将一个文件分割为多个文件,然后再组合成一个文件
		* 找到文件,读入一个1M的buffer中,然后写入一个Part文件中,循环此操作直到文件读取完毕
		*/

		String sourceFilePath = "D:" + File.separator + "Code" + File.separator + "source" + File.separator + "031316_【第13章：Java类集】_属性类：Properties.wmv";
		int partFileLength = 1024*1024;//指定分割的子文件大小为1M
		splitFile(sourceFilePath,partFileLength);//将文件分割
		combineFile("D:" + File.separator + "Code" + File.separator + "target");//将分割后的文件合并
	}

	public static void combineFile(String directoryPath) throws Exception
	{
		Properties config = new Properties();
		InputStream ips = null;
		ips = new FileInputStream(new File(directoryPath + File.separator + "config.properties"));
		config.load(ips);

		Set keySet = config.keySet();//需要将keySet转换为int型
		
		
		//将keySet迭代出来,转换成int类型的set,排序后存储进去
		Set intSet = new TreeSet();
		Iterator iterString = keySet.iterator();
		while(iterString.hasNext())
		{
			String tempKey = (String)iterString.next();
			if("name".equals(tempKey))
			{}
			else
			{
				int tempInt ;
				tempInt = Integer.parseInt(tempKey);
				intSet.add(tempInt);
			}
		}
		
		Set sortedKeySet = new TreeSet();
		sortedKeySet.addAll(intSet);

		OutputStream eachFileOutput = null;
		eachFileOutput = new FileOutputStream(new File("D:" + File.separator + "Code" + File.separator + config.getProperty("name")));

		Iterator iter = sortedKeySet.iterator();
		while(iter.hasNext())
		{
			String key = new String("" + iter.next());
			if(key.equals("name"))
			{}
			else
			{
				//System.out.println("debug---");
				String fileNumber = null;
				String filePath = null;
				fileNumber = key;
				filePath = config.getProperty(fileNumber);

				//循环读取文件 --> 依次写入

				InputStream eachFileInput = null;
				
				eachFileInput = new FileInputStream(new File(filePath));
				
				byte[] buffer = new byte[1024*1024*1];//缓冲区文件大小为1M
				int len = 0;
				while((len = eachFileInput.read(buffer,0,1024*1024*1)) != -1)
				{
					eachFileOutput.write(buffer,0,len);
				}
				eachFileInput.close();
			}
		}

		eachFileOutput.close();
	}

	public static void splitFile(String sourceFilePath,int partFileLength) throws Exception 
	{
		File sourceFile = null;
		File targetFile = null;
		InputStream ips = null;
		OutputStream ops = null;
		OutputStream configOps = null;//该文件流用于存储文件分割后的相关信息，包括分割后的每个子文件的编号和路径,以及未分割前文件名
		Properties partInfo = null;//properties用于存储文件分割的信息
		byte[] buffer = null;
		int partNumber = 1;
		sourceFile = new File(sourceFilePath);//待分割文件
		ips = new FileInputStream(sourceFile);//找到读取源文件并获取输入流
		configOps = new FileOutputStream(new File("D:" + File.separator + "Code" //配置文件
			+ File.separator + "target" + File.separator + "config.properties"));
		buffer = new byte[partFileLength];//开辟缓存空间
		int tempLength = 0;
		partInfo = new Properties();//key:1开始自动编号 value:文件路径

		while((tempLength = ips.read(buffer,0,partFileLength)) != -1) 
		{
			String targetFilePath = "D:" + File.separator + "Code" 
				+ File.separator + "target" + File.separator + "part_" + (partNumber);//分割后的文件路径+文件名
			partInfo.setProperty((partNumber++)+"",targetFilePath);//将相关信息存储进properties
			targetFile = new File(targetFilePath);
			ops = new FileOutputStream(targetFile);//分割后文件
			ops.write(buffer,0,tempLength);//将信息写入碎片文件

			ops.close();//关闭碎片文件
		}
		partInfo.setProperty("name",sourceFile.getName());//存储源文件名
		partInfo.store(configOps,"ConfigFile");//将properties存储进实体文件中
		ips.close();//关闭源文件流
	}
}