Second-level caching and configuration principles

The second level cache is a process or cluster-wide cache that can be shared by all sessions

Secondary cache is a configurable plug-in

01. Configuration Use of Level two cache (Ehcache cache)

* * Introduce the following jar package.

Ehcache-1.2.3.jar Core Library

Backport-util-concurrent.jar

Commons-logging.jar

Configure Hibernate.cfg.xml to turn on level two caching

<property name= "Hibernate.cache.use_second_level_cache" >true</property>

Configure a two-level cache vendor

<property name= "Hibernate.cache.provider_class" >org.hibernate.cache.EhCacheProvider</property>

Configuring in a large configuration file (Hibernate.cfg.xml)

<class-cache    usage= "Read-write" class= "cn.happy.entity.Student"/><collection-cache usage= " Read-write "collection=" "/>

The second-level cache holds the data principle:

Second-level cache testing:

/**     * Test level Two cache     *        /@Test public           void Testbulk () {               //Get the data like                  session session = Hibernateutil.getsession ();               Transaction tx=session.begintransaction ();               Dept Dept = (Dept) session.get (dept.class,1);               System.out.println (Dept.getdeptname ());               Tx.commit ();               Hibernateutil.closesession ();               System.out.println ("===========================");                              SQL statements are not displayed because there is a level two cache               Session session2 = hibernateutil.getsession ();               Transaction tx2=session2.begintransaction ();               Dept dept2 = (Dept) session2.get (dept.class,1);               System.out.println (Dept2.getdeptname ());               Tx2.commit ();               Hibernateutil.closesession ();                       }

Operation Result:

Because there is a level two cache, it is the query department name, so the second query does not display the SQL statement

To test the query cache:

List () method

/** * * * * */         @Test public        void Testcache () {            session=hibernateutil.getsession ();            Transaction tx=session.begintransaction ();            Query query = Session.createquery ("from Emp");                        List () can only put data can   not be removed            list<emp> List = Query.list ();            for (Emp emp:list) {                System.out.println (Emp.getempname ());            }            System.out.println ("================================");                        Do not display sql: The previous step has been placed in        level two cache            list<emp> list1 = Query.list ();            for (Emp emp:list1) {                System.out.println (Emp.getempname ());            }                        System.out.println ("================================");             }

Run results

First put the data, the list () method can only put into the data, cannot take out the data, so when the query statement, the display of two SQL statements, which shows that the IST () method can only put data, cannot take out data, memory address is different, so display two SQL statements

Iterate () method

Operation Result:

The iterate () method can fetch the data, run the query statement, display two SQL, but these two SQL is not the same, confirming the iterate () method can take out the data

Second-level caching and configuration principles