【java爬虫】将优惠券数据存入数据库排序查询

**Java爬虫实践：优惠券数据存入数据库排序查询**

在本文中，我们将使用Java编程语言来实现一个简单的爬虫程序，用于抓取优惠券数据，并将其存储到数据库中。我们还会展示如何对这些数据进行排序和查询。

**环境准备**

* Java Development Kit (JDK)8或更高版本* MySQL数据库（本例中使用MySQL，但其他关系型数据库也可以）
* Apache Commons Lang库（用于字符串操作等功能）

### **爬虫程序设计**

我们的爬虫程序将从指定的网站抓取优惠券数据，然后将其存储到MySQL数据库中。我们还会实现对这些数据的排序和查询功能。

#### **爬虫类**

首先，我们定义一个名为`CouponCrawler`的类，负责抓取优惠券数据：

javapublic class CouponCrawler {
 private static final String URL = " //目标网站URL public List crawl() throws IOException {
 //使用HttpURLConnection或OkHttp库发送GET请求获取网页内容 HttpURLConnection connection = (HttpURLConnection) new URL(URL).openConnection();
 connection.setRequestMethod("GET");
 connection.connect();

 //解析网页内容，提取优惠券数据 Document document = Jsoup.parse(connection.getInputStream(), "UTF-8", URL);
 Elements coupons = document.select("div.coupon");

 List couponList = new ArrayList<>();
 for (Element coupon : coupons) {
 Coupon couponData = parseCoupon(coupon);
 couponList.add(couponData);
 }

 return couponList;
 }

 private Coupon parseCoupon(Element element) {
 //解析单个优惠券元素，提取相关数据 String title = element.select("h2.title").text();
 String description = element.select("p.description").text();
 String discount = element.select("span.discount").text();

 return new Coupon(title, description, discount);
 }
}

javapublic class CouponDatabase {
 private static final String DB_URL = "jdbc:mysql://localhost:3306/coupons"; //数据库连接URL private static final String USER = "root"; //数据库用户名 private static final String PASS = "password"; //数据库密码 public void saveCoupons(List coupons) {
 try (Connection connection = DriverManager.getConnection(DB_URL, USER, PASS);
 PreparedStatement statement = connection.prepareStatement("INSERT INTO coupons (title, description, discount) VALUES (?, ?, ?)")) {

 for (Coupon coupon : coupons) {
 statement.setString(1, coupon.getTitle());
 statement.setString(2, coupon.getDescription());
 statement.setString(3, coupon.getDiscount());

 statement.executeUpdate();
 }
 } catch (SQLException e) {
 System.err.println("Error saving coupons to database: " + e.getMessage());
 }
 }

 public List queryCoupons() {
 try (Connection connection = DriverManager.getConnection(DB_URL, USER, PASS);
 Statement statement = connection.createStatement();
 ResultSet resultSet = statement.executeQuery("SELECT * FROM coupons")) {

 List couponList = new ArrayList<>();
 while (resultSet.next()) {
 Coupon couponData = parseCoupon(resultSet);
 couponList.add(couponData);
 }

 return couponList;
 } catch (SQLException e) {
 System.err.println("Error querying coupons from database: " + e.getMessage());
 return Collections.emptyList();
 }
 }

 private Coupon parseCoupon(ResultSet resultSet) throws SQLException {
 String title = resultSet.getString("title");
 String description = resultSet.getString("description");
 String discount = resultSet.getString("discount");

 return new Coupon(title, description, discount);
 }
}

javapublic class Main {
 public static void main(String[] args) {
 CouponCrawler crawler = new CouponCrawler();
 List coupons = crawler.crawl();

 CouponDatabase database = new CouponDatabase();
 database.saveCoupons(coupons);

 List sortedCoupons = database.queryCoupons();
 System.out.println("Sorted Coupons:");
 for (Coupon coupon : sortedCoupons) {
 System.out.println(coupon.getTitle() + ": " + coupon.getDiscount());
 }
 }
}