war/src/main/java/pnews/servlet/ArticleStore.java

   1 package pnews.servlet;
   2
   3 import java.lang.ref.WeakReference;
   4 import java.util.HashMap;
   5
   6 import pnews.Article;
   7
   8 public class ArticleStore {
   9         public final static ArticleStore singleton = new ArticleStore();
  10         private final HashMap<String, WeakReference<Article>> articles = new HashMap<>();
  11
  12         public Article get(String link) {
  13                 WeakReference<Article> ref;
  14
  15                 synchronized (articles) {
  16                         ref = articles.get(link);
  17                         if (ref == null)
  18                                 return null;
  19                         return ref.get();
  20                 }
  21         }
  22
  23         public Article getArticle(String link, ArticleFactory factory) {
  24                 Article result;
  25
  26                 synchronized (articles) {
  27                         result = get(link);
  28                         if (result == null) {
  29                                 result = factory.create();
  30                                 articles.put(link, new WeakReference<>(result));
  31                         }
  32
  33                         return result;
  34                 }
  35         }
  36 }