详解JAVA抓取网页的图片,JAVA利用正则表达式抓取网站图片

利用Java抓取网页上的所有图片：

用两个正则表达式：

1、匹配html中img标签的正则：<img.*src=(.*?)[^>]*?>

2、匹配img标签中得src中http路径的正则：http:/"?(.*?)(/"|>|//s+)

实现：

package org.swinglife.main;  import java.io.File; import java.io.FileOutputStream; import java.io.InputStream; import java.net.URL; import java.net.URLConnection; import java.util.ArrayList; import java.util.List; import java.util.regex.Matcher; import java.util.regex.Pattern;  /***  * java抓取网络图片  * @author swinglife  *  */ public class CatchImage {    // 地址   private static final String URL = "http://www.csdn.net";   // 编码   private static final String ECODING = "UTF-8";   // 获取img标签正则   private static final String IMGURL_REG = "<img.*src=(.*?)[^>]*?>";   // 获取src路径的正则   private static final String IMGSRC_REG = "http:/"?(.*?)(/"|>|//s+)";       public static void main(String[] args) throws Exception {     CatchImage cm = new CatchImage();     //获得html文本内容     String HTML = cm.getHTML(URL);     //获取图片标签     List<String> imgUrl = cm.getImageUrl(HTML);     //获取图片src地址     List<String> imgSrc = cm.getImageSrc(imgUrl);     //下载图片     cm.Download(imgSrc);   }         /***    * 获取HTML内容    *    * @param url    * @return    * @throws Exception    */   private String getHTML(String url) throws Exception {     URL uri = new URL(url);     URLConnection connection = uri.openConnection();     InputStream in = connection.getInputStream();     byte[] buf = new byte[1024];     int length = 0;     StringBuffer sb = new StringBuffer();     while ((length = in.read(buf, 0, buf.length)) > 0) {       sb.append(new String(buf, ECODING));     }     in.close();     return sb.toString();   }    /***    * 获取ImageUrl地址    *    * @param HTML    * @return    */   private List<String> getImageUrl(String HTML) {     Matcher matcher = Pattern.compile(IMGURL_REG).matcher(HTML);     List<String> listImgUrl = new ArrayList<String>();     while (matcher.find()) {       listImgUrl.add(matcher.group());     }     return listImgUrl;   }    /***    * 获取ImageSrc地址    *    * @param listImageUrl    * @return    */   private List<String> getImageSrc(List<String> listImageUrl) {     List<String> listImgSrc = new ArrayList<String>();     for (String image : listImageUrl) {       Matcher matcher = Pattern.compile(IMGSRC_REG).matcher(image);       while (matcher.find()) {         listImgSrc.add(matcher.group().substring(0, matcher.group().length() - 1));       }     }     return listImgSrc;   }    /***    * 下载图片    *    * @param listImgSrc    */   private void Download(List<String> listImgSrc) {     try {       for (String url : listImgSrc) {         String imageName = url.substring(url.lastIndexOf("/") + 1, url.length());         URL uri = new URL(url);         InputStream in = uri.openStream();         FileOutputStream fo = new FileOutputStream(new File(imageName));         byte[] buf = new byte[1024];         int length = 0;         System.out.println("开始下载:" + url);         while ((length = in.read(buf, 0, buf.length)) != -1) {           fo.write(buf, 0, length);         }         in.close();         fo.close();         System.out.println(imageName + "下载完成");       }     } catch (Exception e) {       System.out.println("下载失败");     }   }     } 

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