public static void main(String[] args) {
   UrlValue uv = null;
   while (true) {
     uv = new UrlValue();
     uv.url = "12345678901234567890";
     uv.value = 1;
     add(uv);
     System.out.println(size());
   }
 }
 // 清除所有优先队列的数据,设置优先种子
 private static void SetSeeds(String filepath) throws Exception {
   pq.clear();
   BufferedReader br = new BufferedReader(new FileReader(filepath));
   String line = null;
   UrlValue cur = null;
   visitedPrint();
   while ((line = br.readLine()) != null) {
     line = line.trim();
     // System.out.println(line);
     if (!line.equals("")) {
       if (!visitedUrl.contains(line)) {
         cur = new UrlValue();
         cur.url = line;
         cur.value = 1;
         pq.offer(cur);
       } else {
         System.out.println("contain");
       }
     }
   }
   br.close();
 }
  // 加载待访问的url
  private static void SetPriorQueue(String filePath) throws Exception {
    BufferedReader br = new BufferedReader(new FileReader(filePath));
    Scanner sc = null;
    String line = null;
    String url = null;
    UrlValue cur = null;

    while ((line = br.readLine()) != null) {
      line = line.trim();
      if (!line.equals("")) {
        sc = new Scanner(line);
        url = sc.next();
        if (!visitedUrl.contains(url)) {
          cur = new UrlValue();
          cur.url = url;
          cur.value = sc.nextDouble();
          pq.offer(cur);
        }
      }
    }
    br.close();
  }
 public static void add(UrlValue url) {
   if (url != null && !url.url.trim().equals("") && !visitedUrl.contains(url.url)) {
     url.url = url.url.trim();
     pq.offer(url);
   }
 }