The process of file splitting and merging using Java stream operations

This article mainly introduces relevant information on detailed examples of splitting and merging files by java stream operations. I hope this article can help everyone understand and master this part of the content. Friends who need it can refer to it

Detailed explanation of examples of splitting and merging files by java stream operations

Learn the input and output streams of files and make a small example to split and merge files.

The following is the code:

package com.dufy.file; 
 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.SequenceInputStream; 
import java.util.ArrayList; 
import java.util.Collections; 
import java.util.Enumeration; 
import java.util.List; 
/** 
 * 文件的切割和合并 
 * 1.要切割和合并文件：主要考虑的就是文件的源地址，目标地址，暂存文件地址和文件名称 
 * 2.切割文件：判断给的暂存地址是否存在，不存在，则创建；从源地址中读出文件，按照给定的大小进行文件的切割操作放入暂存地址中 
 * 3.合并文件：判断给定的目标地址是否存在，不存在，则创建；定义List集合将暂存地址中的文件全部读取出来，放到list集合中 
 *     然后使用Enumeration列举出所有文件，合并流合并文件 
 *     最后写入到目标的地址中 
 * 注:本例子中所有的异常都采用抛出的方式处理 
 * @author aflyun 
 * 
 */ 
public class TestFileCutUnion { 
 
  public static void main(String[] args) throws IOException { 
     
    String fSrc = "D:/1.jpg";//源文件的目录 
    String fDir = "D:/1";//目标文件的目录 
    String fTemp = "D:/2";//暂存文件的目录 
    File srcFile = new File(fSrc); 
    File dirFile = new File(fDir); 
    File tempFile = new File(fTemp); 
    String fileName = srcFile.getName();//获取文件的名称 
    cutFile(srcFile,tempFile);//调用分割方法 
    unionFile(dirFile,tempFile,fileName);//调用合并方法 
     
     
  } 
   
  /** 
   * 切割文件 
   * @param srcFile 
   * @param tempFile 
   * @throws IOException 
   */ 
   
  public static void cutFile(File srcFile, File tempFile) throws IOException { 
    //读取源地址文件 
    FileInputStream fis = new FileInputStream(srcFile); 
    FileOutputStream fos = null; 
    //是否为文件，不是就创建 
    if(!tempFile.isFile()){ 
      tempFile.mkdirs(); 
    } 
   
    byte[] b = new byte[100]; 
    int len =0; 
    int count = 0; 
    while((len=fis.read(b)) != -1){ 
      int num = count++; 
      //写入暂存地址目录中 
      fos = new FileOutputStream(new File(tempFile, num+".part")); 
      fos.write(b, 0, len); 
       
    } 
    fos.flush(); 
    fos.close(); 
    fis.close(); 
     
    System.out.println("分割完成！"); 
  } 
  /** 
   * 合并文件 
   * @param dirFile 
   * @param tempFile 
   * @param fileName 
   * @throws IOException 
   */ 
  public static void unionFile(File dirFile, File tempFile, String fileName) throws IOException { 
    //判断目标地址是否存在，不存在则创建 
    if(!dirFile.isFile()){ 
      dirFile.mkdirs(); 
    } 
    List<FileInputStream> list = new ArrayList<FileInputStream>(); 
    //获取暂存地址中的文件 
    File[] files = tempFile.listFiles(); 
     
    for (int i = 0; i < files.length; i++) { 
      //用FileInputStream读取放入list集合 
      list.add(new FileInputStream(new File(tempFile, i+".part"))); 
    } 
    //使用 Enumeration（列举） 将文件全部列举出来 
    Enumeration<FileInputStream> eum = Collections.enumeration(list); 
    //SequenceInputStream合并流 合并文件 
    SequenceInputStream sis = new SequenceInputStream(eum); 
    FileOutputStream fos = new FileOutputStream(new File(dirFile, fileName)); 
    byte[] by = new byte[100]; 
    int len; 
    while((len=sis.read(by)) != -1){ 
      fos.write(by, 0, len); 
    } 
    fos.flush(); 
    fos.close(); 
    sis.close(); 
    System.out.println("合并完成！"); 
  } 
}

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