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 
  } 
}