Java爬虫

作为一位Java爬虫的初学者，分享一下自己的心得。
所用到的jar包

org.codehaus.jettison.jar

jsoup-1.7.3.jar

个人认为爬虫的实现机制：
获取Docume对象—>获取节点—>输出或者持久化

获取页面的图片地址

获取Docume对象—>获取Img元素—>输出地址

 package com.cn.basic;

 import java.io.IOException;
 import org.jsoup.Jsoup;
 import org.jsoup.nodes.Document;
 import org.jsoup.nodes.Element;
 import org.jsoup.select.Elements;

 public class ImageDemo1 {

     public static void Get_Url(String htmlUrl, String path) {

         try {
             Document doc = Jsoup.connect(htmlUrl).get();

             Element body = doc.body();
             Elements elements = body.select("img");

             String src = "";
             for (Element element : elements) {

                 src = element.attr("src");

                 System.out.println(path + src);

             }

             System.out.println("elements-size: " + elements.size());

         } catch (IOException e) {
             e.printStackTrace();
         }

     }

     public static void main(String[] args) {

         String url = "http://pic.netbian.com/4kkatongdongman/index_2.html";
         String path = "http://pic.netbian.com";
         Get_Url(url, path);

     }

 }

将图片写入本地

获取Docume对象—>获取Img元素—>将图片保存本地

 package com.cn.basic;

 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;
 import java.util.Date;

 import org.jsoup.Jsoup;
 import org.jsoup.nodes.Document;
 import org.jsoup.nodes.Element;
 import org.jsoup.select.Elements;

 public class ImageDemo2 {

     public static void saveImage(String htmlUrl, String path) {

         try {
             Document doc = Jsoup.connect(htmlUrl).get();
             Element body = doc.body();
             Elements elements = body.select("img");

             String outputFilePath="E:/pythonTest/javaPython/imgs/";
             String src = "";

             HttpURLConnection conn = null;
             InputStream inStream = null;
             byte[] data = null;
             String filePath = null;
             FileOutputStream outStream = null;

             Long startTime=new Date().getTime();

             for (Element element : elements) {

                 src = element.attr("src");

                 System.out.println(path + src);
                 // new一个URL对象

                 if (!src.contains(".jpg")) {
                     continue;
                 }

                 URL url = new URL(path + src);
                 // 打开链接
                 conn = (HttpURLConnection) url.openConnection();
                 // 设置请求方式为"GET"
                 conn.setRequestMethod("GET");
                 // 超时响应时间为5秒
                 conn.setConnectTimeout(5 * 1000);
                 // 通过输入流获取图片数据
                 inStream = conn.getInputStream();
                 // 得到图片的二进制数据，以二进制封装得到数据，具有通用性
                 data = readInputStream(inStream);
                 // new一个文件对象用来保存图片，默认保存当前工程根目录
                 filePath = outputFilePath + System.currentTimeMillis() + ".jpg";
                 // 创建输出流
                 outStream = new FileOutputStream(new File(filePath));
                 // 写入数据
                 outStream.write(data);
                 // 关闭输出流
                 outStream.close();

             }
             System.out.println(elements.size());
             System.out.println("读写速度："+(new Date().getTime()-startTime)+"毫秒");

         } catch (IOException e) {
             e.printStackTrace();
         } catch (Exception e) {
             e.printStackTrace();
         }

     }

     public static byte[] readInputStream(InputStream inStream) throws Exception {
         ByteArrayOutputStream outStream = new ByteArrayOutputStream();
         // 创建一个Buffer字符串
         byte[] buffer = new byte[1024];
         // 每次读取的字符串长度，如果为-1，代表全部读取完毕
         int len = 0;
         // 使用一个输入流从buffer里把数据读取出来
         while ((len = inStream.read(buffer)) != -1) {
             // 用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度
             outStream.write(buffer, 0, len);
         }
         // 关闭输入流
         inStream.close();
         // 把outStream里的数据写入内存
         return outStream.toByteArray();
     }

     public static void main(String[] args) {
         String url = "http://pic.netbian.com/4kkatongdongman/index_2.html";
         String path = "http://pic.netbian.com";
         saveImage(url, path);
     }

 }