Jsoup（三）-- Jsoup使用选择器语法查找DOM元素

1.Jsoup可以使用类似于CSS或jQuery的语法来查找和操作元素.

2.实例如下：

    public static void main(String[] args) throws Exception{
        // 创建httpClient实例
        CloseableHttpClient httpClient = HttpClients.createDefault();
        // 创建httpGet实例
        HttpGet httpGet = new HttpGet("http://www.cnblogs.com");
        httpGet.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0");
        CloseableHttpResponse response = httpClient.execute(httpGet);
        String content = null;
        if(response != null){
            HttpEntity entity = response.getEntity();   
            content = EntityUtils.toString(entity, "UTF-8");  // 获取网页内容
            Document document = Jsoup.parse(content);  // 解析网页，得到文档对象
            
            // 1.查找所有帖子DOM
            Elements elements = document.select(".post_item .post_item_body h3 a");
            for(Element ele : elements){
                System.out.println("博客标题：" + ele.text());
            }
            System.out.println("------------------------分割线------------------------");
            
            // 2.查找带有href属性的a元素
            Elements hrefElements = document.select("a[href]");
            for(Element ele : hrefElements){
                System.out.println(ele.toString());
            }
            System.out.println("------------------------分割线------------------------");
            
            // 3.查找扩展名为.png的图片DOM节点
            Elements imgElements = document.select("img[src$=.png]");
            for(Element ele : imgElements){
                System.out.println(ele.toString());
            }
            System.out.println("------------------------分割线------------------------");
            
            // 4.获取tag为title的第一个DOM元素
            Element titleEle = document.getElementsByTag("title").first();
            System.out.println("标题为：" + titleEle.text());
        }
        if(response != null){
            response.close();
        }
        if(httpClient != null){
            httpClient.close();
        }
    }

3.Jsoup学习地址

　　开源博客系统-Jsoup