java - A pattern for stack of urls -

-

i have following question. have application set of jsps , action classes control interaction user. actions set parameters required page display properly. urls in system contain name of event defines page should go next.

now, every page has cancel button should lead previous page. start each cancel button url strictly defined, eventually, system grew larger , larger, turned out quite hard program logic button lead previous page.

for example, suppose have 3 pages, a, b , c. page has link leading page b, , b has link leading c. therefore c has url leading b (and contains key of entity display on b). however, suppose page modified , has link on c. need check on c page there came , set url appropriately, , logic becomes pretty mixed.

so, proposed team following solution. user session should contain special object called cancelstack. every action, leads page, should push it's url inside stack (containing event , additional data required). on every page cancel button should have url leading special event, called cancelstack.

what cancelstack action this:

  • retrieve cancel stack session.
  • pop last url , not use it.
  • pop url again , redirect url.

why retrieve last url without using? suppose have pages , b, leading b. action places it's url inside stack, , should cancel url b page. now, action b places it's url inside stack. therefore pop without using, , pop first url, redirect action, , action adds url again stack (therefore stack size decreases 1, not 2).

it seems pretty scheme, seems rather strange top element of stack popped without using. therefore have question. there design patter in order store sequence of urls inside session in order organise cancel buttons properly?

what did seems reasonable me. honest can't think of design pattern addressing issue right now, think if besides cancelstack keep reference currenturl push currenturl stack if don't end in cancel page rid of pop annoys you.
otherwise pop top of cancelstack.
e.g. in example:

suppose have pages , b, leading b...

currenturl a. action not cancel currenturl i.e. a pushed cancelstack. action b , currenturl b action cancel b not placed in stack. top of cancelstack a (while currenturl b). if pop cancelstack retrieve a (no pop needed)


Comments

Post a Comment

Popular posts from this blog

c# - SVN Error : "svnadmin: E205000: Too many arguments" -

-
i trying reposotries using c# code process svncommand = null; var psi = new processstartinfo("svnadmin"); psi.redirectstandardoutput = true; psi.redirectstandarderror = true; psi.useshellexecute = false; psi.arguments= @"dump c:\repositories\myrepo > c:\temp\myrepodumpfile.dump"; using (svncommand = process.start(psi)) { var myoutput = svncommand.standardoutput; var myerror = svncommand.standarderror; debug.write("output :" + environment.newline + environment.newline + myoutput.readtoend() + environment.newline + "error :" + environment.newline + environment.newline + myerror.readtoend()); svncommand.close(); } when use dump command commandline svnadmin dump c:\repositories\myrepo > c:\temp\myrepodumpfile.dump it works fine when try ...
Read more

c++ - Using OpenSSL in a multi-threaded application -

-
i have been writing soap client application in c++ on ubuntu using openssl https transport , pthreads threading. have number of threads - 1 central data acquisition thread periodically gets worker threads make soap requests via shared mutex protected queues. reading documentation openssl found is openssl thread-safe? in openssl faq describes mechanisms required ensure thread safety when using openssl. implemented , works fine. the reason question conceptual difficulty really. thinking implementing same functionality application has already, instead of using threads, create 2 seperate applications : 1 worker thread (of multiple copies running) , main data acquisition thread. use tcp sockets communicate between 2 rather mutex protected queues. may bad idea not important - confusing me would have implement same functions required ensure openssl thread safety in second approach or not? my guess not have , treated independent (indeed surely must many applications use openssl) re...
Read more

All overlapping substrings matching a java regex -

-
is there api method returns (possibly overlapping) substrings match regular expression? for example, have text string: string t = 04/31 412-555-1235; , , have pattern: pattern p = new pattern("\\d\\d+"); matches strings of 2 or more characters. the matches are: 04, 31, 412, 555, 1235. how overlapping matches? i want code return: 04, 31, 41, 412, 12, 55, 555, 55, 12, 123, 1235, 23, 235, 35. theoretically should possible -- there obvious o(n^2) algorithm enumerates , checks substrings against pattern. edit rather enumerating substrings, safer use region(int start, int end) method in matcher . checking pattern against separate, extracted substring might change result of match (e.g. if there non-capturing group or word boundary check @ start/end of pattern). edit 2 actually, it's unclear whether region() expect zero-width matches. specification vague, , experiments yield disappointing results. for example: string line = "xx90xx"; strin...
Read more