大多數情況下，我們要獲取頁面源碼等html代碼中的某個標籤的某個屬性值時，不可能大費周章的去使用第三方框架，這就有點牛刀殺雞的趕腳了。遇到這種情況我們可以使用簡單的正則表達式來提取我們想要的數據。
例如，我要下個連續劇，大多數網站提供給我們的是很多列表，需要我們去一個一個去點擊，這就很麻煩，現在，只需要我們使用http獲取到頁面的html字符串，然後使用正則表達式批量獲取到a標籤的href屬性的值就可以了。
現在我們以某電影網站某雷下載爲例，現在demo如下：
工具方法httpSendGet：
public static String httpSendGet(String url, String param,String charsetName) {
String result = "";
BufferedReader in = null;
try {
String urlNameString = url + "?" + param;
URL realUrl = new URL(urlNameString);
// 打開和URL之間的連接
URLConnection connection = realUrl.openConnection();
// 設置通用的請求屬性
connection.setRequestProperty("accept", "*/*");
connection.setRequestProperty("connection", "Keep-Alive");
connection.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
// 建立實際的連接
connection.connect();
// 定義 BufferedReader輸入流來讀取URL的響應
in = new BufferedReader(new InputStreamReader(
connection.getInputStream(), charsetName));
String line;
while ((line = in.readLine()) != null) {
result += line;
}
} catch (Exception e) {
System.out.println("發送GET請求出現異常！" + e);
e.printStackTrace();
}
// 使用finally塊來關閉輸入流
finally {
try {
if (in != null) {
in.close();
}
} catch (Exception e2) {
e2.printStackTrace();
}
}
return result;
}工具方法match：
public static List<String> match(String source, String element, String attr) {
List<String> result = new ArrayList<String>();
String reg = "<" + element + "[^<>]*?\\s" + attr + "=['\"]?(.*?)['\"]?(\\s.*?)?>";
Matcher m = Pattern.compile(reg).matcher(source);
while (m.find()) {
String r = m.group(1);
result.add(r);
}
return result;
}調用demo：
public static void main(String[] args) {
String url = "https://www.dy2018.com/i/99671.html";
String params = "";
String html = httpSendGet(url,params,"gb2312");
List<String> links = match(html,"a","href");
System.out.println(links);
}這裏需要說明一下，httpSendGet的charsetName參數需要注意，不然你獲取的html文本會是亂碼。
最後展示一下結果(當然結果還不純粹，需要過濾)：
[/, /2/, /0/, /3/, /1/, /4/, /8/, /5/, /7/, /14/, /15/, /html/tv/hytv/index.html, /html/tv/oumeitv/index.html, /html/tv/rihantv/index.html, /html/zongyi2013/index.html, /html/dongman/index.html, /support/GuestBook.php, #, index.html, /, /html/tv/, /html/tv/hytv/, javascript:window.external.addFavorite('http://www.dy2018.com/','dy2018.com-電影天堂')"class="style11, /webPlay/play-id-99671-collection-37.html, /webPlay/play-id-99671-collection-36.html, /webPlay/play-id-99671-collection-35.html, /webPlay/play-id-99671-collection-34.html, /webPlay/play-id-99671-collection-33.html, /webPlay/play-id-99671-collection-32.html, /webPlay/play-id-99671-collection-31.html, /webPlay/play-id-99671-collection-30.html, /webPlay/play-id-99671-collection-29.html, /webPlay/play-id-99671-collection-28.html, /webPlay/play-id-99671-collection-27.html, /webPlay/play-id-99671-collection-26.html, /webPlay/play-id-99671-collection-25.html, /webPlay/play-id-99671-collection-24.html, /webPlay/play-id-99671-collection-23.html, /webPlay/play-id-99671-collection-22.html, /webPlay/play-id-99671-collection-21.html, /webPlay/play-id-99671-collection-20.html, /webPlay/play-id-99671-collection-19.html, /webPlay/play-id-99671-collection-18.html, /webPlay/play-id-99671-collection-17.html, /webPlay/play-id-99671-collection-16.html, /webPlay/play-id-99671-collection-15.html, /webPlay/play-id-99671-collection-14.html, /webPlay/play-id-99671-collection-13.html, /webPlay/play-id-99671-collection-12.html, /webPlay/play-id-99671-collection-11.html, /webPlay/play-id-99671-collection-10.html, /webPlay/play-id-99671-collection-9.html, /webPlay/play-id-99671-collection-8.html, /webPlay/play-id-99671-collection-7.html, /webPlay/play-id-99671-collection-6.html, /webPlay/play-id-99671-collection-5.html, /webPlay/play-id-99671-collection-4.html, /webPlay/play-id-99671-collection-3.html, /webPlay/play-id-99671-collection-2.html, /webPlay/play-id-99671-collection-1.html, /webPlay/play-id-99671-collection-0.html, ftp://g:[email protected]:2166/一千零一夜35.mp4, ftp://g:[email protected]:2166/一千零一夜34.mp4, ftp://g:[email protected]:2166/一千零一夜33.mp4, ftp://g:[email protected]:2166/一千零一夜32.mp4, ftp://g:[email protected]:2166/一千零一夜31.mp4, ftp://g:[email protected]:2166/一千零一夜30.mp4, ftp://g:[email protected]:2166/一千零一夜29.mp4, ftp://g:[email protected]:2166/一千零一夜28.mp4, ftp://g:[email protected]:2166/一千零一夜27.mp4, ftp://g:[email protected]:2166/一千零一夜26.mp4, ftp://g:[email protected]:2166/一千零一夜25.mp4, ftp://g:[email protected]:2166/一千零一夜24.mp4, ftp://g:[email protected]:2166/一千零一夜23.mp4, ftp://g:[email protected]:2166/一千零一夜22.mp4, ftp://g:[email protected]:2166/一千零一夜21.mp4, ftp://g:[email protected]:2166/一千零一夜20.mp4, ftp://g:[email protected]:2166/一千零一夜19.mp4, ftp://g:[email protected]:2166/一千零一夜18.mp4, ftp://g:[email protected]:2166/一千零一夜17.mp4, ftp://g:[email protected]:2166/一千零一夜16.mp4, ftp://g:[email protected]:2166/一千零一夜15.mp4, ftp://g:[email protected]:2166/一千零一夜14.mp4, ftp://g:[email protected]:2166/一千零一夜13.mp4, ftp://g:[email protected]:2166/一千零一夜12.mp4, ftp://g:[email protected]:2166/一千零一夜11.mp4, ftp://g:[email protected]:2166/一千零一夜10.mp4, ftp://g:[email protected]:2166/一千零一夜09.mp4, ftp://g:[email protected]:2166/一千零一夜08.mp4, ftp://g:[email protected]:2166/一千零一夜07.mp4, ftp://g:[email protected]:2166/一千零一夜06.mp4, ftp://g:[email protected]:2166/一千零一夜05.mp4, ftp://g:[email protected]:2166/一千零一夜04.mp4, ftp://g:[email protected]:2166/一千零一夜03.mp4, ftp://g:[email protected]:2166/一千零一夜02.mp4, ftp://g:[email protected]:2166/一千零一夜01.mp4, /i/99743.html, /i/99734.html, /i/99733.html, /i/99725.html, /i/99720.html, /i/99719.html, /i/99716.html, /i/99708.html, /i/99704.html, /i/99695.html, /i/97129.html, /i/97575.html, /i/97041.html, /i/92091.html, /i/97637.html, /i/92020.html, /i/95187.html, /i/92000.html, /i/98343.html, /i/97363.html]
不想自己寫正則表達式，可以使用第三方爬蟲框架，這方面網上找很多的，我就不寫了。