Question

我正在尝试处理Java中的会话。每当有人进入新页面时，我都需要增加一个视图值，但是每个会话每个用户只需增加一次。此刻下面的代码没有做到这一点，它一直在增加。我认为问题可能在于每次加载页面时，arraylist都会重新变新吗？我不确定如何处理。由于对象在刷新后不会停留在数组中。

用于处理会话并尝试增加计数的代码 //获取图片名称 session.setAttribute（“ pictureName”，pictureName）;

    // create a list of objects that will store all the pages a user visits
    ArrayList<String> listOfObjects = new ArrayList<String>();

    // make a image_id variable but assign it the value of the page name
    String image_id = (String) session.getAttribute("pictureName");

    // go and compare each element in the list, to the id.
    // This should NOT match on the first viewing since it's the first time the user
    // visits the page
    // this should then increment the view count
    if (Utilities.isFirstVisit(listOfObjects, image_id) == true) {
        Utilities.IncreaseCount(out, pictureName);
        out.println("its worked");

    } else {
        // if a match is found then the user has already visited this page
        // therefore don't increment the view count for the love of christ
        out.println("A match was found");

    }

被调用以将对象添加或不添加到数组列表的方法

public static boolean isFirstVisit(ArrayList <String> listOfObjects,
            String image_id) {
        System.out.println(listOfObjects);
        System.out.println(image_id);

    if(listOfObjects.contains(image_id)) {
        System.out.println("It does contain");
        System.out.println(image_id);
        return false;
    }

    else { 
        listOfObjects.add(image_id);
        System.out.println("It does not contain");
        System.out.println(image_id);
        return true;
        }
    }

增加观看次数的方法

//Increase the access count on the picture
    public static void IncreaseCount(PrintWriter out, String pictureName) {

        Connection con = null;
        try { // Connect to the database
            con = openConnection(out);
        } catch (Exception e) { // Failed to open the connection
            out.println("<P>" + e.getMessage());
            return;
        }

        try {

            Statement stmt = con.createStatement();
            String query;
            ResultSet rs1;

            query = "UPDATE Statistics SET AccessCount = AccessCount + 1 WHERE PictureNo = (SELECT PictureNo FROM Pictures WHERE FileName = '"
                    + pictureName + "')";

            stmt.executeUpdate(query);

            stmt.close();

        } catch (SQLException ex) {
            out.println("<P>SQLException: " + ex.getMessage());
        }

    }

＃

Updated只是每会话更新一张图片，而不是每会话更新所有访问过的图片

   if(session.getAttribute("myVisitedPages") == null) {
           ArrayList<String> listOfPages = new ArrayList<String>();

           session.setAttribute("myVisitedPages", listOfPages);

            if (Utilities.isFirstVisit(listOfPages, pictureName) == true) {
                Utilities.IncreaseCount(out, pictureName);
                out.println("its worked");

            } 
       }

Answer 1

您必须在会话中存储访问页面的列表。

这是流程：

尝试从“ myVisitedPages”会话中获取属性
第一次是null。创建一个new ArrayList()，使用setAttribute将其附加到会话上，然后向其添加首页ID。
第二次以后，该列表将作为会话属性提供，您可以获取该列表，并检查该列表内部。

（顺便说一句，我不确定为什么您当前访问的页面ID需要在会话中存在。）

更新后。如果不应该嵌套：

  ArrayList<String> listOfPages = session.getAttribute("myVisitedPages");
  if(listOfPages == null) {
       listOfPages = new ArrayList<String>();

       session.setAttribute("myVisitedPages", listOfPages);
   }

   if (Utilities.isFirstVisit(listOfPages, pictureName) == true) {
       Utilities.IncreaseCount(out, pictureName);
       out.println("its worked");
   }

Answer 2

好吧，据我所知，你想要太多增量每次有新访问时的柜台也是网络看法如果是这样的话。声明一个

HttpSession obj = request.getSession();
obj.setSessionAttribute("image_id", null);
  
  If (obj.getAttribute("image_id") == null){
     Write_to_db();
     string value="user counted";
     obj.setSessionAttribute("image_id", value); 
     }

将会话值附加到Java中的数组

＃

2 个答案: