java远程下载图片

从别的网站复制文章的时候，要把图片下载到我们网站，再把图片地址换成我们网站的地址

<img id="mbkenHUwhWeOj9U8K6c8LlAXaes3oXit-M4SnmRvB4wXXEue2ol7MviqfDlnDFgp.jpg" alt="图片" onerror="NextPic(‘/attached/image/mbkenHUwhWeOj9U8K6c8LlAXaes3oXit-M4SnmRvB4wXXEue2ol7MviqfDlnDFgp.jpg‘,‘mbkenHUwhWeOj9U8K6c8LlAXaes3oXit-M4SnmRvB4wXXEue2ol7MviqfDlnDFgp.jpg‘);" src="http://localhost:8080/attached/image/mbkenHUwhWeOj9U8K6c8LlAXaes3oXit-M4SnmRvB4wXXEue2ol7MviqfDlnDFgp.jpg">

<script type="text/javascript">
window.NextPic=function(url,name){
    var cb = "http://localhost:8080"+url
    console.log("haha");
    var src = document.getElementById(name).src
    if(src.indexOf("rcwimg")<=0) return;
    document.getElementById(name).src = cb;
}
</script>

public class WaNewsInfoVo extends Page<WaNewsInfo>{

    private Integer id;
    private String title;
    private Integer typeId;
    private String typeName;
    private Integer typeId2;
    private String typeName2;
    private String logo;
    private String content;
    private String createTime;
    private String createUser;
    private String createUserName;
    private String tag1;
    private String tag2;
    private Integer isDisplay;
    private Integer browser;
    private String summary;
}

　　// 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|https):\"?(.*?)(\"|>|\\s+)";

　　//添加或者修改资讯
	public int insertOrUpdate(HttpServletRequest request, WaNewsInfoVo vo){
		String aaa = "/attached/image/";
		String path = request.getSession().getServletContext().getRealPath("../")+ "/attached/image/";
		//获取图片标签
		List<String> imgUrl = getImageUrl(vo.getContent());
		//获取图片src地址
        List<String> imgSrc = getImageSrc(imgUrl);
        //下载图片
        Download(imgSrc,path);
        String test = replaceHtmlTag(vo.getContent(),"img","src","src=\""+aaa,"\"");
        vo.setContent(test);
		if(CommUtil.isEmpty(vo.getId())){
			vo.setBrowser(0);
			return waNewsDao.insert(vo);
		}
		return waNewsDao.update(vo);
	}

   /***
     * 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, String path) {
        try {
            for (String url : listImgSrc) {
                if(url.indexOf("http")>=0){
                String imageName = url.substring(url.lastIndexOf("/") + 1, url.length());
                URL uri = new URL(url);
                InputStream in = uri.openStream();
                FileOutputStream fo = new FileOutputStream(new File(path,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(path+imageName + "下载完成");
                }
            }
        } catch (Exception e) {
            System.out.println("下载失败");
        }
    }     

替换img标签

    /**
     * 替换指定标签的属性和值
     * @param str 需要处理的字符串
     * @param tag 标签名称
     * @param tagAttrib 要替换的标签属性值
     * @param startTag 新标签开始标记
     * @param endTag  新标签结束标记
     * @return
     * @author huweijun
     * @date 2016年7月13日 下午7:15:32
     */
    public static String replaceHtmlTag(String str, String tag, String tagAttrib, String startTag, String endTag) {
        //匹配以<img开头>结尾
        String regxpForTag = "<\\s*" + tag + "\\s+([^>]*)\\s*" ;
        //匹配src="开头，"结尾
        String regxpForTagAttrib = tagAttrib + "=\\s*\"([^\"]+)\"" ;
        //编译后的正则表达式
        Pattern patternForTag = Pattern.compile (regxpForTag,Pattern. CASE_INSENSITIVE );
        Pattern patternForAttrib = Pattern.compile (regxpForTagAttrib,Pattern. CASE_INSENSITIVE );
        //先查<img标签
        Matcher matcherForTag = patternForTag.matcher(str);
        StringBuffer sb = new StringBuffer();
        //如果有结果
        boolean result = matcherForTag.find();
        while (result) {
            StringBuffer sbreplace = new StringBuffer( "<"+tag+" ");
            //查到的第一个<img,再匹配src
            Matcher matcherForAttrib = patternForAttrib.matcher(matcherForTag.group(1));
            if (matcherForAttrib.find()) {
                String attributeStr = matcherForAttrib.group(1);
                String imageName = attributeStr.substring(attributeStr.lastIndexOf("/") + 1, attributeStr.length());
                sbreplace.append("id=‘"+imageName+"‘ alt=‘图片‘ onerror=\"NextPic(‘/attached/image/"+imageName+"‘,‘"+imageName+"‘);\"");
                matcherForAttrib.appendReplacement(sbreplace, startTag + "rcwimg" + endTag);
            }
            matcherForAttrib.appendTail(sbreplace);
            matcherForTag.appendReplacement(sb, sbreplace.toString());
            result = matcherForTag.find();
        }
        matcherForTag.appendTail(sb);
        return sb.toString();
    }