Java’s example of splitting a file into multiple subfiles and then merging the subfiles into the original file is as follows:

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
  {
    /*
    * will 1 Three files split into multiple files , And then combine them again 1 A file
    *  Find the file , Read in 1 a 1M the buffer In the , Then write 1 a Part In the file , This operation is looped until the file is read
    */

    String sourceFilePath = "D:" + File.separator + "Code" + File.separator + "source" + File.separator + "031316_ The first 13 Chapter: Java Class set 】 _ Properties: Properties.wmv";
    int partFileLength = 1024*1024;// Specifies the size of the split subfile as 1M
    splitFile(sourceFilePath,partFileLength);// Split the file
    combineFile("D:" + File.separator + "Code" + File.separator + "target");// Merge the split files
  }

  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();// You need to keySet convert int type


    // will keySet Iterative out , Converted to int The type of set, Sort it and store it in
    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);

        // Loop read file  -->  Write in turn

        InputStream eachFileInput = null;

        eachFileInput = new FileInputStream(new File(filePath));

        byte[] buffer = new byte[1024*1024*1];// The buffer file size is 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;// This file stream is used to store information about the split file, including the number and path of each child file after the split , And the name of the file before the split
    Properties partInfo = null;//properties Used to store information about file segmentation
    byte[] buffer = null;
    int partNumber = 1;
    sourceFile = new File(sourceFilePath);// Split file
    ips = new FileInputStream(sourceFile);// Find the read source file and get the input stream
    configOps = new FileOutputStream(new File("D:" + File.separator + "Code" // The configuration file
      + File.separator + "target" + File.separator + "config.properties"));
    buffer = new byte[partFileLength];// Open up cache space
    int tempLength = 0;
    partInfo = new Properties();//key:1 Start autonumbering  value: The file path

    while((tempLength = ips.read(buffer,0,partFileLength)) != -1)
    {
      String targetFilePath = "D:" + File.separator + "Code"
        + File.separator + "target" + File.separator + "part_" + (partNumber);// Split file path + The file name
      partInfo.setProperty((partNumber++)+"",targetFilePath);// Store the relevant information in properties
      targetFile = new File(targetFilePath);
      ops = new FileOutputStream(targetFile);// Split file
      ops.write(buffer,0,tempLength);// Writes the information to the shard file

      ops.close();// Close the fragment file
    }
    partInfo.setProperty("name",sourceFile.getName());// Store source file name
    partInfo.store(configOps,"ConfigFile");// will properties Store it in an entity file
    ips.close();// Close the source file flow
  }
}