package com.xuecheng.media;

import org.apache.commons.codec.digest.DigestUtils;
import org.apache.commons.io.IOUtils;
import org.junit.jupiter.api.Test;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.*;

public class BigFileTest {
    //測(cè)試文件分塊方法
    @Test
    public void testChunk() throws IOException {

File sourceFile = new File("d:/develop/bigfile_test/nacos.mp4");
String chunkPath = "d:/develop/bigfile_test/chunk/";
File chunkFolder = new File(chunkPath);
if (!chunkFolder.exists()) {
    chunkFolder.mkdirs();
}

//分塊大小
long chunkSize = 1024 * 1024 * 1;
//分塊數(shù)量
long chunkNum = (long) Math.ceil(sourceFile.length() * 1.0 / chunkSize);
System.out.println("分塊總數(shù)：" + chunkNum);

//緩沖區(qū)大小
byte[] b = new byte[1024];
//使用RandomAccessFile訪問(wèn)文件
RandomAccessFile raf_read = new RandomAccessFile(sourceFile, "r");
//分塊
for (int i = 0; i < chunkNum; i++) {
    //創(chuàng)建分塊文件
    File file = new File(chunkPath + i);
    if (file.exists()) {
        file.delete();
    }
    boolean newFile = file.createNewFile();
    if (newFile) {
        //向分塊文件中寫數(shù)據(jù)
        RandomAccessFile raf_write = new RandomAccessFile(file, "rw");
        int len = -1;
        while ((len = raf_read.read(b))!= -1) {
            raf_write.write(b, 0, len);
            if (file.length() >= chunkSize) {
                break;
            }
        }
        raf_write.close();
        System.out.println("完成分塊" + i);
    }
}
raf_read.close();

File chunkFolder = new File("D:\\...\\chunk\\");  // 分塊文件目錄
File sourceFile = new File("D:\\...\\星際牛仔1.mp4");  // 原始文件
File mergeFile = new File("D:\\...\\星際牛仔1-1.mp4");  // 合并后的文件
mergeFile.createNewFile();  // 創(chuàng)建空的目標(biāo)文件

RandomAccessFile raf_write = new RandomAccessFile(mergeFile, "rw");  // 以讀寫模式打開(kāi)合并文件
byte[] buffer = new byte[1024];  // 讀寫緩沖區(qū)（1KB）

//listFiles（）表示返回目錄中所有文件和子目錄的File數(shù)組，files是包含所有分塊文件的數(shù)組
File[] files = chunkFolder.listFiles();
//將數(shù)組轉(zhuǎn)換為list集合，fileList是包含所以分塊文件的list<File>
List<File> fileList = Arrays.asList(files);
//然后對(duì)List進(jìn)行排序，Comparator.comparingInt創(chuàng)建一個(gè)比較器，按照指定規(guī)則排序（將文件名轉(zhuǎn)換為整數(shù)進(jìn)行排序）
Collections.sort(fileList, Comparator.comparingInt(o -> Integer.parseInt(o.getName())));

//循環(huán)遍歷分塊文件列表
for (File chunkFile : fileList) {
//以只讀模式打開(kāi)分塊文件 "r"表示以只讀模式打開(kāi)
    RandomAccessFile raf_read = new RandomAccessFile(chunkFile, "r"); 
//讀取分塊文件內(nèi)容并寫入合并文件
    int len;
    while ((len = raf_read.read(buffer)) != -1) {  
        raf_write.write(buffer, 0, len);  
    }
    raf_read.close();  // 關(guān)閉分塊文件流
}
raf_write.close();  // 關(guān)閉合并文件流