Advanced Cache Objects in Java

**StudyBoy** · 28-07-2010

Before complicate life designing a caching system, it is very possible that we should look online at the usual places, to see what there is on the subject. In the Java world, we must not forget how it defines the new specifications. This is through the JCP (Java community process).

Looking up, we find that there is a recommended product functionality for caching, called OSCACHE. After downloading the ZIP file with the libraries and documentation, so that our proof of concept work, we can establish a file structure.

**StudyBoy** · 28-07-2010

We must modify the web.xml file to reference library TAGS:

Code:

<taglib>
      <taglib-uri> oscache </ taglib-uri>
      <taglib-location> / WEB-INF/oscache.tld </ taglib-location>
 </ Taglib>

We also have to play the oscache.properties configuration file and display the contents persistent cache directory.

Code:

 # CACHE DIRECTORY # # 
This is the directory on disk caches WHERE will be stored by the DiskPersistenceListener. 
# It will be created if it does Already exist.  Remember That OSCache must-have 
# write permission to this directory. 
# # Note: for Windows machines, this Needs \ to be escaped # ie Windows:
# cache.path = c: \ \ myapp \ \ cache # or * ix: # cache.path = / opt / myapp / cache 
# cache.path = d: \ \ cacheadictos \ \ WEB-INF \ \ cache

Our JSP, refers to a tag library in order to have the game of TAGS to help us in our work:
<% @ Taglib uri = "oscache" prefix = "cache"%>
Declaring an area that we want to cache is as simple as including a block like this:
<Cache: cache key = "Zona1" scope = "application" duration = "10">
Depending on the type of application and scope of the cache element can play with different modifiers: key, scope and duration (see the documentation for more details and other related labels). We have specified that we want all users have this cached content and every 10 seconds to cool.

**StudyBoy** · 28-07-2010

To prove that it behaves as we want, we'll put a delay in one area and run the query several times .... the result will surprise you. As usual in this web, look on substance rather than form .....

HTML Code:

 <% @ Taglib uri = "oscache" prefix = "cache"%>
 <% @ Page contentType = "text / html"%>
 <html>
 <title> <head> JSP Page </ title> </ head>
 <body>

 <%!  int counter = 0;%>

 <center>
 Examples of Caches <h1> with OSCache </ h1>

 <% Long start = System.currentTimeMillis (); 

  counter + +; 
  %>
 <br>

 <Cache: cache key = "Zona1" scope = "application" duration = "10">

  <% 

  try 
  ( 
      Thread.currentThread (). Sleep (3000); 

      java.util.Date date = new java.util.Date (); 

      out.println ("This is the message" + date); 
  ) 
  catch (Exception e) () 

  %> 

 </ Cache: cache> 

 <br>

 <%  

  long end = System.currentTimeMillis () - start; 
  out.println ("The full time is:" + order 
 + "Milliseconds and the counter is:" + counter);%> </ center> </ body> </ html>

In a normal application, the time should always be greater than three seconds .... but we see that indeed the time of the second request goes to zero ...

This example can be very useful when working with the MVC design pattern type 1 (using JavaBeans and JSP tags to access data structures). If we continue researching the product, we will soon see that there is an object model equivalent for other applications using MVC design as type 2 or traditional applications.