java - Including an Entity Class programmatically with a persistence unit? -

i looking on code created awhile ago, , noticed odd.

i creating persistence unit programmatically due needed user input location of database read.

my code follows

 map properties = new hashmap();                db = plan.db;               // configure internal eclipselink connection pool             properties.put(transaction_type, persistenceunittransactiontype.resource_local.name());             properties.put(jdbc_driver, "net.ucanaccess.jdbc.ucanaccessdriver");             properties.put(jdbc_url, "jdbc:ucanaccess://" + db + ";singleconnection=‌​true;memory=true");             properties.put(jdbc_user, "");             properties.put(jdbc_password, "");           //  properties.put( "provider" , "org.eclipse.persistence.jpa.persistenceprovider");             entitymanagerfactory emf2;             entitymanager em2;              emf2 = persistence.createentitymanagerfactory("pu", properties);             em2 = emf2.createentitymanager();     

with able create connections multiple times.

the problem noticed had code in "persistence.xml"

 <persistence-unit name="pu" transaction-type="resource_local"> <provider>org.eclipse.persistence.jpa.persistenceprovider</provider> <class>db.items</class> <exclude-unlisted-classes>false</exclude-unlisted-classes> <properties>   <property name="javax.persistence.jdbc.url" value=""/>   <property name="javax.persistence.jdbc.user" value=""/>   <property name="javax.persistence.jdbc.driver" value="net.ucanaccess.jdbc.ucanaccessdriver"/>   <property name="javax.persistence.jdbc.password" value=""/> </properties> 

now noticed cannot find way add "entity class" "persistence unit," able run code fine, this.

i'm curious if overwrites old properies , such persistence unit of same name? still uses persistence class of "db.items."

i want make sure correct way it.

i'm doing changes code, cannot run see if delete in persistence.xml happen, i'm curious this.

i noticed "provider" property commented out. need posted? (it's included in xml file).

there example saw mentioned "server target" being set "no" or something? comments on that?

thanks all

it overwrites properties have specified in persistence.xml. can example set user name , password in way , other properties used defined in file. if it's "right" way don't know, have done same.

the call persistence.createentitymanager(unit, props) starts searching named unit in persistence.xml found in classpath. properties props added or overwritten properties read file unit.

i have no comment other questions.