Java将文件分割为多个子文件再将子文件合并成原始文件的示例

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<Integer> intSet = new TreeSet<Integer>();     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<Integer> sortedKeySet = new TreeSet<Integer>();     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   } }