import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

/**
 * Java讀取并下載網絡文件
 * @author Marydon
 * @createTime 2017年8月18日下午5:24:09
 * @updateTime
 * @Email:marydon2017@163.com
 * @version:1.0.0
 * @referenceLink
 * <a href="http://blog.csdn.net/xb12369/article/details/40543649/"> java 從網絡Url中下載文件</a>
 */
public class DownloadFromNetwork {
  /** 
   * 從網絡Url中下載文件 
   * @param urlStr 
   * @param fileName 
   * @param savePath 
   * @throws IOException 
   */ 
  public static void downLoadFromUrl(String urlStr,String fileName,String savePath) throws IOException{ 
    URL url = new URL(urlStr);  
    HttpURLConnection conn = (HttpURLConnection)url.openConnection();  
        //設置超時間為3秒 
    conn.setConnectTimeout(3*1000); 
    //防止屏蔽程序抓取而返回403錯誤 
    conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)"); 
 
    //得到輸入流 
    InputStream inputStream = conn.getInputStream();  
    //獲取自己數組 
    byte[] getData = readInputStream(inputStream);   
 
    //文件保存位置 
    File saveDir = new File(savePath); 
    if(!saveDir.exists()){ 
      saveDir.mkdirs(); 
    } 
    File file = new File(saveDir+File.separator+fileName);   
    FileOutputStream fos = new FileOutputStream(file);    
    fos.write(getData);  
    if(fos!=null){ 
      fos.close();  
    } 
    if(inputStream!=null){ 
      inputStream.close(); 
    } 
 
    System.out.println("info:"+url+" download success");  
 
  } 
 
  /** 
   * 從輸入流中獲取字節數組 
   * @param inputStream 
   * @return 
   * @throws IOException 
   */ 
  public static byte[] readInputStream(InputStream inputStream) throws IOException {  
    byte[] buffer = new byte[1024];  
    int len = 0;  
    ByteArrayOutputStream bos = new ByteArrayOutputStream();  
    while((len = inputStream.read(buffer)) != -1) {  
      bos.write(buffer, 0, len);  
    }  
    bos.close();  
    return bos.toByteArray();  
  }  
 
  public static void main(String[] args) { 
    try{ 
      for (int i = 201; i <=520; i++) {
        downLoadFromUrl("https://cache.yisu.com/upload/information/20200623/121/112271.jpg",i + ".jpg","E:/Downloads/wallpaper/baiduSkin"); 
      }
    }catch (Exception e) { 
      // TODO: handle exception 
    } 
  } 
}