Jsoup（二）-- Jsoup查找DOM元素

    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.根据tag获取元素
             */
            Elements elements = document.getElementsByTag("title"); // 获取 tag为 title的DOM元素
            Element element = elements.get(0); // 获取第一个DOM元素
            String title = element.text();  // 返回元素的文本
            System.out.println("博客园的标题：" + title);
            
            /**
             * 2.根据 id获取元素
             */
            Element element2 = document.getElementById("site_nav_top");
            String navTop = element2.text();
            System.out.println("座右铭：" + navTop);
            
            /**
             * 3.根据样式获取元素
             */
            Elements elements3 = document.getElementsByClass("post_item");
            System.out.println("============根据样式获取元素=============");
            for(Element e : elements3){
                System.out.println(e.html());
                System.out.println("------------------------------");
            }
            
            /**
             * 4.根据属性名称来查询DOM
             */
            Elements elements4 = document.getElementsByAttribute("width");
            System.out.println("============根据属性名称来查询DOM=============");
            for(Element e : elements4){
                System.out.println(e.toString());
                System.out.println("------------------------------");
            }
            
            /**
             * 5.根据属性名和属性值来查询DOM
             */
            Elements elements5 = document.getElementsByAttributeValue("target", "_blank");
            System.out.println("============ 根据属性名和属性值来查询DOM=============");
            for(Element e : elements5){
                System.out.println(e.toString());
                System.out.println("------------------------------");
            }
        }
        if(response != null){
            response.close();
        }
        if(httpClient != null){
            httpClient.close();
        }
    }