思路

主要先是通过java实现http请求获取到我们需要下载图片的网址，然后根据图片的网址通过字节写入本地文件夹中

代码

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Getphoto {
	private static ArrayList<String> urls = new ArrayList<String>();
	//集合 存储
	private static String url_end=null;
	//最后匹配得到的图片url（需拼接）
	private static int	z=1;
	//图片名字和计次
	
	public static void httpget(String geturl) {
		//构造httpget请求函数 
		try {			
			HttpURLConnection urlConnection = null;			
			URL url = new URL(geturl);
			//url对象初始化			
			urlConnection  = (HttpURLConnection)url.openConnection();
			//建立连接
			urlConnection.setConnectTimeout(5000);
			//连接超时设置5s
			urlConnection.setReadTimeout(5000);
			//读取超时5s  获取响应
			urlConnection.setUseCaches(false);
			//不使用缓存
			urlConnection.setRequestProperty("user-agent","Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.25 Safari/537.36 Core/1.70.3706.400 SLBrowser/10.0.4040.400" );
			//添加协议头 请求需要时可以添加其它
			urlConnection.connect();	
			BufferedReader html =new BufferedReader(new InputStreamReader(urlConnection.getInputStream(),"GBK"));
			//编码为gbk
			String line = html.readLine();
			//读取下一行内容
			while(line!=null) {
				//循环遍历每一遍的内容
				Matcher matchingid = Pattern.compile("<a href=\"/tupian/(.*?).html").matcher(line);
				//正则匹配id	<a href=\"/tupian/(.*?).html为正则表达式		line为被匹配的数据
				while(matchingid.find()) {
					urls.add(matchingid.group(1));
					//matchingid.group(1)为匹配的文本
				}	
				Matcher matchingurl_end = Pattern.compile("<img src=\"(.*?)\" data-pic").matcher(line);
				while(matchingurl_end.find()) {
					url_end = matchingurl_end.group(1);
				}
				line = html.readLine();
			}
		}catch (Exception e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
	}

	
	private static void downloadPicture(String urlList,String path) {
		//构造根据图片url下载图片函数
        URL url = null;
        try {
            url = new URL(urlList);
          //url对象初始化
            DataInputStream dataInputStream = new DataInputStream(url.openStream());
            //初始化数据输入流读数据    url.openStream()获取url资源的输入流
            FileOutputStream fileOutputStream = new FileOutputStream(new File(path));
            //初始化输出流写数据
            ByteArrayOutputStream output = new ByteArrayOutputStream();
            //初始化字节数组输出流，把数据写入到自己的数组中,数组的大小会随着数据的不断增加而自动增长
            byte[] buffer = new byte[1024];
            int length;
            while ((length = dataInputStream.read(buffer)) > 0) {
                output.write(buffer, 0, length);
            }
            fileOutputStream.write(output.toByteArray());
            dataInputStream.close();//关闭流
            fileOutputStream.close();//关闭流
        } catch (Exception e) {
            e.printStackTrace();
        } 
    }
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String url = ""; 
		int sore=11;
		File file ;
		for(int i=1;i<sore;i++) {
			if(i==1) {
				url = "http://pic.netbian.com/index.html";
			}else if(i>1) {
				url = "http://pic.netbian.com/index_"+i+".html";
			}
			httpget(url);
			for(int j = 0;j<urls.size();j++) {
				httpget("http://pic.netbian.com/tupian/"+urls.get(j)+".html");
				file = new File("C:\\Users\\Lenovo\\Desktop\\images");
				//创建文件夹对象
		        if (!file.exists()) { 
		        	//如果文件夹不存在  则创建一个空的文件夹
		            file.mkdirs();
		        }
		        downloadPicture("http://pic.netbian.com"+url_end, "C:\\Users\\Lenovo\\Desktop\\images\\"+z+".jpg");
				z = z + 1;
				if(j==20) {
					urls.removeAll(urls);//清空集合
				}
			}		
		}	
	}

	
}