Ask a question about session, prawns help!

blankness0

That's it. I participated in a large-scale web project. The front desk was developed using struts. When writing the application, some front desk applications require a lot of business data (public data, which is needed for many front desk displays, about a dozen. Data in each table, each table has about 100 rows), in order to prevent repeated reading of the database, each time the user logs in (when the session is initialized) I put the data into a dozen Arraylist (basically a table (Corresponding to an ArrayList), put the ArrayList into the session through session.setAttribute, so that when the page is used, you can directly read data from the session.
However, when testing later, I found that when displaying data in an ArrayList, there will be garbled characters or other data that should not appear.
For example: Originally ArrayList should save: "Gender, Male, Female"
      The results show: "Student distribution, Dongcheng Branch, ........." This was originally the contents of several other ArrayLists, how did they fit into this ArrayList? Could it be a memory or page problem?

This phenomenon is very random. I can't figure out why. Ask everyone for advice. Thank you very much.

Suspected possible problems:

Possible cause of the problem
(1) Server version issue
(2) Memory overlap may occur: when multiple users initialize a session, they copy the data in the locked code table to their own session. In combination with the Linux memory management mechanism, a page overlap may occur.
(3) In addition, JAVA's data storage mechanism is mostly in a heap manner, which may cause overlap of memory data

Has anyone encountered a similar situation? Tell me!

chen96542

If the amount of data is large, don't put it in the session, it is very memory-intensive

blankness0

I know this is the case, but there is no choice but to do it. Is this the case if there is a lot of data stored in the session?

流氓鱼

Post code to take a look.

bfbf7878

Oh, it’s a lot of memory to see this for the first time.

hannah2222

First, what do you use to achieve data persistence
Second, how do you deal with session issues

blankness0

initsession
Initialize session
import javax.servlet.http.HttpSession;

public class InitSession {
   public InitSession() {
   }

   /**
     * Initialize the variables that should be saved in the session, including code and logger.
     * @param session HttpSession
     * @throws Exception
     */
   public static void init(HttpSession session) throws Exception {
       initCode(session);
// initLogger(session);
   }

   /**
     * Initialize code.
     * @param session HttpSession
     * @throws Exception
     */
   private static void initCode(HttpSession session) throws Exception {
       if(session.getAttribute( "_CodeManager ")!=null)return;
// CommonLogger.getInstance().getLogger().info( "Start to initialize code");

       CodeManager codeManager = CodeManager.getInstance();
       codeManager.initCode();
       session.setAttribute( "_CodeManager ", codeManager);
       session.setAttribute( "_auditState ", codeManager.queryAuditState());
       session.setAttribute( "_census ", codeManager.queryCensus());
       session.setAttribute( "_educationalLevel ", codeManager.queryEducationalLevel());
       session.setAttribute( "_education ", codeManager.queryEducation()); //Professional code of the Education Commission
       session.setAttribute( "_studentType ", codeManager.queryStudentType());
       session.setAttribute( "_subschool ", codeManager.querySubschool());
       session.setAttribute( "_station ",codeManager.queryStation());
       session.setAttribute( "_testSubject ", codeManager.queryTestSubject());
       session.setAttribute( "_year ", codeManager.queryYear());
// System.out .println( "dddd "+codeManager.queryYear().size());
       session.setAttribute( "_manageType ",codeManager.queryManageType());
       session.setAttribute( "_stuType ",codeManager.queryStuType());
       session.setAttribute( "_classGrade ",codeManager.queryClassgrade());
       session.setAttribute( "_distributed ",codeManager.queryDistributed());
       session.setAttribute( "_examSort ",codeManager.queryExamSort());//Exam category
       session.setAttribute( "_examSchoolType ",codeManager.queryExamSchoolType());//Exam unit type
       session.setAttribute( "_examItem ",codeManager.queryExamItem());//Exam item
       session.setAttribute( "_employState ",codeManager.QueryEmployState() );//Employment status
       session.setAttribute( "_statusState ",codeManager.queryStatusState() );
       session.setAttribute( "_RewardPunishmentCode ",codeManager.queryRewardPunishmentCode() );
       session.setAttribute( "_RewardLevelCode ",codeManager.queryRewardLevelCode() );
       session.setAttribute( "_UndoSignalCode ",codeManager.queryUndoSignalCode() );
       session.setAttribute( "_RewardPunishmentReason ",codeManager.queryRewardPunishmentReason() );
       session.setAttribute( "_englishDegree ",codeManager.queryEnglishDegree());//English approval code

       session.setAttribute( "_socialCourse ",codeManager.querySocialCourse());//Social course code (degree)

       session.setAttribute( "_punishiment ",codeManager.queryPunishment());//The degree penalty approval code
       session.setAttribute( "_score ",codeManager.queryScore());//Score code
       session.setAttribute( "_teachDep ",codeManager.queryTeachDep());//Teaching department
       session.setAttribute( "_institution ",codeManager.queryInstitution());//Institution
       session.setAttribute( "_firstFocus ",codeManager.queryFirstFocus());//First time again
       session.setAttribute( "_examTypeAlias ​​",codeManager.queryExamTypeAlias());//The evaluation method alias
       session.setAttribute( "_startMark ",codeManager.queryStartMark());//Enable flag (course, teaching point professional)
       session.setAttribute( "_approveMark ",codeManager.queryApproveMark());//Course approval mark
       session.setAttribute( "_cancelMark ",codeManager.queryCancelMark());//Course stop sign
       session.setAttribute( "_mediaType ", codeManager.queryMediaType()); //Media type
       session.setAttribute( "_haveMark ", codeManager.queryHaveMark()); //A code table
       session.setAttribute( "_generalCourse ", codeManager.queryGeneralCourse()); //General course list
       session.setAttribute( "_generalCourse_IdName ", codeManager.queryGeneralCourse_IdName()); //General course list
       session.setAttribute( "_transCode ", codeManager.queryTransCode()); //Transfer code
         session.setAttribute( "_transCodeUp ", codeManager.queryTransCodeUp()); //Upload transmission code
           session.setAttribute( "_transCodeReceive ", codeManager.queryTransCodeReceive()); //Receive transmission code
       session.setAttribute( "_openSpeciality ", codeManager.queryOpenSpeciality()); //Open professional
       session.setAttribute( "_credentialType ", codeManager.queryCredentialType()); //Certificate type
       session.setAttribute( "_socialSubjcetSort ",codeManager.querySocialSubjcetSort());//Social subject category
       session.setAttribute( "_examStateCode ",codeManager.queryExamStateCode());//The audit status code table
       session.setAttribute( "_netExamCourse ",codeManager.queryNetExamCourse());//Net test subjects
       CommonLogger.getInstance().getLogger().debug( "Initialized code completion");
   }
}

kider11

On the contrary, it was a garbled problem for a long time. I thought it was all changed to UTF-8 format.

blankness0

Brother, see it clearly, it is not a garbled problem, the corresponding item extracted from the corresponding session.setAttribute is not garbled, but incorrect data, for example: originally the session.getAttribute ("sex") should get "male" "female" , But now the content of other items is obtained, for example: "Beijing" "Shijiazhuang" "Jinan"............ Moreover, this phenomenon is not reproducible. He will appear on any machine anytime, anywhere, on different machines, so he can't figure out what is going on. Now it is mainly suspected that it is a memory problem, and the session is suspected. Overlap. I don't know if anyone has encountered this situation.

qiqituo

Try not to write this, if you don’t cross the page, you can directly encapsulate it again in VECTOR, and then submit it to the next page, or claim a temporary file and read it again, or claim a temporary table in the database. If you do this, you will definitely have problems, and Irregular problems, you can find the root cause of Microsoft, after all, do not understand the core wit of SESSION