package DownLoadDemo;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.RandomAccess;

public class DownLoaderTest {
    private static final int MAX_SIZE_BUFF = 1024 * 1024 * 10;     //1MB大小
    //網絡視頻路徑
    private static String path = "//www.iqiyi.com/v_uggavqs43w.html";
    private static String writePath = "111.mp4";
    public static void main(String[] args) throws IOException {
        //網絡協議對象（遠程對象）
        HttpURLConnection urlConnection = null;
        //定位網絡資源
        URL url = new URL(path);
        //調用url的openConnection（）連接遠程對象
        urlConnection = (HttpURLConnection) url.openConnection();
        //設置遠程對象的參數和屬性:"Range" : 範圍，" 0-":沒有終止位元組數，支持斷點續傳 
        urlConnection.setRequestProperty("Range", "bytes=0-");
        //發送連接請求，實現真正的連接
        urlConnection.connect();
        //通過返回碼，判斷是否連接成功(200以內是成功的)
        int code = urlConnection.getResponseCode();
        if(code / 100 != 2) {    //請求失敗
            throw new RuntimeException("請求失敗，返回碼:" + code + "錯誤");
        }
        //遠程對象連接成功後，創建遠程對象輸入流
        InputStream inputStream = urlConnection.getInputStream();
        //創建bufferedInputStream
//        BufferedInputStream bInStream = new BufferedInputStream(inputStream);
//        //使用RandomAccess工具類
//        RandomAccessFile randomAccess = new RandomAccessFile(path, "rw");
        //創建緩衝位元組數組buff
        byte[] buff = null;
        //開始讀寫
        //1、添加（小技術）打印下載進度（下載的"每塊位元組"位元組數/時間）
        //獲取文件大小
        int fileSize = urlConnection.getContentLength();
        System.out.println(fileSize);
        int downloadedCount = 0;
        while(downloadedCount < fileSize) {
            //分塊，處理一下最後剩餘不足MAX_SIZE_BUFF量
            if(fileSize - downloadedCount > MAX_SIZE_BUFF) {
                buff = new byte[MAX_SIZE_BUFF];
            }else {
                buff = new byte[fileSize - downloadedCount];
            }
            
            int currCount = 0;
            int read = -1;
            long startTime = System.currentTimeMillis();            
//            //讀取
//            bInStream.read(buff);
            while(currCount < buff.length) {
                read = inputStream.read();
                if(read == -1) {
                    break;
                }
                buff[currCount++] = (byte)read;
            }
            if(read == -1) {
                break;
            }
            long endTime = System.currentTimeMillis();
            double speed = currCount / ((endTime - startTime) / 1000.0);    //速度b/s
            System.out.println("讀取速度:" + speed);
            downloadedCount += currCount;
        }
    
    }
}