历史上的今天(java实现实例)

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import java.io.BufferedReader;import java.io.InputStream;import java.io.InputStreamReader;import java.net.HttpURLConnection;import java.net.URL;import java.text.DateFormat;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.regex.Matcher;import java.util.regex.Pattern;/** * 历史上的今天查询服务 *  * @author liufeng * @date 2013-10-16 *  */public class TodayInHistoryService {/** * 发起http get请求获取网页源代码 *  * @param requestUrl * @return */private static String httpRequest(String requestUrl) {StringBuffer buffer = null;try {// 建立连接URL url = new URL(requestUrl);HttpURLConnection httpUrlConn = (HttpURLConnection) url.openConnection();httpUrlConn.setDoInput(true);httpUrlConn.setRequestMethod("GET");// 获取输入流InputStream inputStream = httpUrlConn.getInputStream();InputStreamReader inputStreamReader = new InputStreamReader(inputStream, "utf-8");BufferedReader bufferedReader = new BufferedReader(inputStreamReader);// 读取返回结果buffer = new StringBuffer();String str = null;while ((str = bufferedReader.readLine()) != null) {buffer.append(str);}// 释放资源bufferedReader.close();inputStreamReader.close();inputStream.close();httpUrlConn.disconnect();} catch (Exception e) {e.printStackTrace();}return buffer.toString();}/** * 从html中抽取出历史上的今天信息 *  * @param html * @return */private static String extract(String html) {StringBuffer buffer = null;// 日期标签：区分是昨天还是今天String dateTag = getMonthDay(0);Pattern p = Pattern.compile("(.*)(<div class=\"listren\">)(.*?)(</div>)(.*)");Matcher m = p.matcher(html);if (m.matches()) {buffer = new StringBuffer();if (m.group(3).contains(getMonthDay(-1)))dateTag = getMonthDay(-1);// 拼装标题buffer.append("≡≡ ").append("历史上的").append(dateTag).append(" ≡≡").append("\n\n");// 抽取需要的数据for (String info : m.group(3).split("  ")) {info = info.replace(dateTag, "").replace("（图）", "").replaceAll("</?[^>]+>", "").trim();// 在每行末尾追加2个换行符if (!"".equals(info)) {buffer.append(info).append("\n\n");}}}// 将buffer最后两个换行符移除并返回return (null == buffer) ? null : buffer.substring(0, buffer.lastIndexOf("\n\n"));}/** * 获取前/后n天日期(M月d日) *  * @return */private static String getMonthDay(int diff) {DateFormat df = new SimpleDateFormat("M月d日");Calendar c = Calendar.getInstance();c.add(Calendar.DAY_OF_YEAR, diff);return df.format(c.getTime());}/** * 封装历史上的今天查询方法，供外部调用 *  * @return */public static String getTodayInHistoryInfo() {// 获取网页源代码String html = httpRequest("http://www.rijiben.com/");// 从网页中抽取信息String result = extract(html);return result;}/** * 通过main在本地测试 *  * @param args */public static void main(String[] args) {String info = getTodayInHistoryInfo();System.out.println(info);}}
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