Generic DAO detailed analysis of generic DAO class design pattern (2)

Generic Data Access ObjectsOrdinary data Access object, this is a DAO class design pattern above the official website of Hibernate, based on JDK5.0 type support, the article address is as follows: http://www.hibernate.org/328.html My following code is a little different from what the Hibernate official Web site offers.

First defines the DAO class's interface Igenericdao, which defines common CRUD operations: Java code  /**   *  defines generic crud operations    *  @author  rainlife   */   public Interface igenericdao〈t, ID extends serializable〉{  //& nbsp;  finds an object by its primary key identity.        public t findbyid (id id);          //   to find an object by its primary key identity, you can lock the corresponding record in the table.        t findbyid (id id, boolean lock);           //get all the objects.        list findall ();          // Finds the object that matches it by a given object.        list findbyexample (t exampleinstance);          //the persisted object.        t makepersistent (t entity);           //deletes an object.        void maketransient (t entity);  }   The following is the implementation of the interface using Hibernate Genericdaohibernate:java code  /**   *  This is the hibernate implementation of the Igenericdao interface, Complete the common CRUD operations.    *  @author  rainlife   *  @param   pojo class    *  @param    pojo class's primary key identifier    *  @param    Implementation of the DAO class for each Pojo class     */    Public abstract class genericdaohibernate〈t,id Extends serializable, daoimpl  extends IGenericDAO〈T,ID〉〉        implements  igenericdao〈t,id〉{       private Class persistentClass;          protected Session session;           public genericdaohibernate ()        {            this.persistentclass =  (Class)   ((Parameterizedtype)  getclass ()                     .getgenericsuperclass ()). Getactualtypearguments () [0];       }            @SuppressWarnings ("unchecked")        public daoimpl setsession ( Session s)        {            this.session = s;           return  ( Daoimpl) this;       }          protected  session getsession ()        {            if  (session == null)                  throw new illegalstateexception (                         "Session has not been  set on dao before usage ");            return session;       }           public class getpersistentclass ()        {            return persistentClass;       }                   @SuppressWarnings ("unchecked")        public t findbyid (id id)         {           return  (T)  getsession (). Load ( Getpersistentclass (), &Nbsp;id);       }                @SuppressWarnings ("unchecked")        public t findbyid (ID  id, boolean lock)        {            T entity;           if  ( Lock)                entity =  (T )  getsession (). Load (Getpersistentclass (),  id, lockmode.upgrade);            else                entity = findbyid (ID);               return entity;       }           @SuppressWarnIngs ("unchecked")        public list findall ()         {           return findbycriteria ();        }           @SuppressWarnings ("unchecked")        public list findbyexample (t exampleinstance)        {           criteria crit =  getsession (). Createcriteria (Getpersistentclass ());            example example = example.create (exampleinstance);            crit.add (example);           return  crit.list ();       }                @SuppressWarnings ("unchecked")        public list findbyexample (t exampleinstance, string[] excludeproperty)        {           criteria crit = getsession (). CreateCriteria ( Getpersistentclass ());           example example =  example.create (exampleinstance);           for  ( String exclude : excludeproperty)            {                example.excludeproperty ( Exclude);           }            crit.add (example);           return  crit.list ();       }           @SuppressWarnings (" Unchecked ")        public t makepersistent (t entity)        {           getsession (). saveorupdate (entity);           //getsession (). Save (entity);           return entity;       }           public void maketransient (t entity)         {           getsession (). Delete (entity);        }           @SuppressWarnings (" Unchecked ")        protected list findbycriteria (criterion...  Criterion)        {           criteria crit  = getsession (). Createcriteria (Getpersistentclass ());            for  (criterion c : criterion)             {                Crit.add (c);           }            return crit.list ();       }                @SuppressWarnings ("unchecked")         /**       *  added to the sorting function.        */       protected List  Findbycriteria (order order,criterion... criterion)       {           criteria crit =  getsession (). Createcriteria (Getpersistentclass ());            for  (criterion c : criterion)             {               crit.add (c);            }            if (order!=null)                 Crit.addorder (Order);           return crit.list ();        }              @ Suppresswarnings ("unchecked")        protected list findbycriteria (int  firstresult,int rowcount,order order,criterion... criterion)        {            criteria crit = getsession (). Createcriteria (Getpersistentclass ());           for  ( criterion c : criterion)            {                crit.add (c);            }           if ( Order!=null)                crit.addorder ( Order);           crit.setfirstresult (FirstResult);            crit.setmaxresults (ROWCOUNT);            return crit.list ();       }  }   So, we're going to use the DAO class, You can inherit directly from this hibernate DAO Class: For example, we define an Iuserdao interface that inherits Igenericdao:java code public interface iuserdao  Extends igenericdao〈user,integer〉{       public user find (String  Username,string password);       public user find (String  username);  }    

This interface inherits from Igenericdao and naturally defines the generic CRUD operations defined by the Igenericdao interface. Let's take a look at the hibernate implementation for Iuserdao Userdaohibernate:java code public class Userdaohibernate extends Genericdaohibernate〈user, Integer,iuserdao〉implements Iuserdao {     
        Public user find (String username, string password)  {            //here omit specific code        }          public user find (string username)  {            //here omit specific code        }  }     Userdaohibernate inherits Genericdaohibernate and implements the Iuserdao interface, so that our userdaohibernate has both common crud operations and specific business operations for the user.