fix: address code scanning alerts

src/crawler/MatcherGetter.java

@@ -1,11 +0,0 @@
-package crawler;
-
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
-public class MatcherGetter {
-    public static Matcher getMatcher(String regex, String htmlContent) {
-        Pattern p = Pattern.compile(regex);
-        return p.matcher(htmlContent);
-    }
-}

src/crawler/Test.java

@@ -2,11 +2,15 @@ package crawler;
 
 import java.io.IOException;
 import java.io.PrintWriter;
-import java.util.regex.Matcher;
 
 public class Test {
+    private static final String RANK_MARKER = "<em class=\"\">";
+    private static final String TITLE_MARKER = "<span class=\"title\">";
+    private static final String DIRECTOR_MARKER = "导演: ";
+    private static final String ACTOR_MARKER = "&nbsp;&nbsp;&nbsp;主演: ";
+    private static final String RATING_MARKER = "<span class=\"rating_num\" property=\"v:average\">";
+
     public static void main(String[] args) {
-        String regex = "<em class=\"\">(\\d+)</em>.*?<span class=\"title\">(.*?)</span>.*?导演: (.*?)&nbsp;&nbsp;&nbsp;主演: (.*?)<br>.*?(\\d{4})&nbsp;/&nbsp;.*?<span class=\"rating_num\" property=\"v:average\">(.*?)</span>";
         StringBuilder htmlContent = new StringBuilder();
         htmlContent.append(HtmlFetcher.fetchHtmlContent("https://movie.douban.com/top250"));
         htmlContent.append(HtmlFetcher.fetchHtmlContent("https://movie.douban.com/top250?start=25"));
@@ -18,22 +22,65 @@ public class Test {
         htmlContent.append(HtmlFetcher.fetchHtmlContent("https://movie.douban.com/top250?start=175"));
         htmlContent.append(HtmlFetcher.fetchHtmlContent("https://movie.douban.com/top250?start=200"));
         htmlContent.append(HtmlFetcher.fetchHtmlContent("https://movie.douban.com/top250?start=225"));
-        Matcher m = MatcherGetter.getMatcher(regex, htmlContent.toString());
         StringBuilder movieInfo = new StringBuilder();
         movieInfo.append("豆瓣电影 Top 250\n\n");
-        while (m.find()) {
-            movieInfo.append("排名: ").append(m.group(1)).append("\n");
-            movieInfo.append("电影名: ").append(m.group(2)).append("\n");
-            movieInfo.append("导演: ").append(m.group(3)).append("\n");
-            movieInfo.append("主演: ").append(m.group(4)).append("\n");
-            movieInfo.append("年份: ").append(m.group(5)).append("\n");
-            movieInfo.append("评分: ").append(m.group(6)).append("\n");
+        int searchFrom = 0;
+        String html = htmlContent.toString();
+        while (true) {
+            int rankStart = html.indexOf(RANK_MARKER, searchFrom);
+            if (rankStart == -1) {
+                break;
+            }
+            int nextRank = html.indexOf(RANK_MARKER, rankStart + RANK_MARKER.length());
+            String block = html.substring(rankStart, nextRank == -1 ? html.length() : nextRank);
+            String rank = between(block, RANK_MARKER, "</em>");
+            String title = between(block, TITLE_MARKER, "</span>");
+            String director = between(block, DIRECTOR_MARKER, ACTOR_MARKER);
+            String actor = between(block, ACTOR_MARKER, "<br>");
+            String year = firstYearBefore(block, "&nbsp;/&nbsp;");
+            String rating = between(block, RATING_MARKER, "</span>");
+            if (!rank.isEmpty() && !title.isEmpty() && !rating.isEmpty()) {
+                movieInfo.append("排名: ").append(rank).append("\n");
+                movieInfo.append("电影名: ").append(title).append("\n");
+                movieInfo.append("导演: ").append(director).append("\n");
+                movieInfo.append("主演: ").append(actor).append("\n");
+                movieInfo.append("年份: ").append(year).append("\n");
+                movieInfo.append("评分: ").append(rating).append("\n");
                 movieInfo.append("\n");
             }
+            searchFrom = nextRank == -1 ? html.length() : nextRank;
+        }
         try (PrintWriter out = new PrintWriter("crawler\\movieInfo.txt")) {
             out.println(movieInfo);
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
+
+    private static String between(String text, String startMarker, String endMarker) {
+        int start = text.indexOf(startMarker);
+        if (start == -1) {
+            return "";
+        }
+        start += startMarker.length();
+        int end = text.indexOf(endMarker, start);
+        if (end == -1) {
+            return "";
+        }
+        return text.substring(start, end).trim();
+    }
+
+    private static String firstYearBefore(String text, String endMarker) {
+        int end = text.indexOf(endMarker);
+        if (end == -1) {
+            return "";
+        }
+        for (int index = Math.max(0, end - 16); index + 4 <= end; index++) {
+            String candidate = text.substring(index, index + 4);
+            if (candidate.chars().allMatch(Character::isDigit)) {
+                return candidate;
+            }
+        }
+        return "";
+    }
 }