The design of Basedao and its implementation class based on Hibernate

I used to design the DAO interface and its implementation, this way you do not have to write so many duplicate code. But because there is no understanding of reflection, it cannot be written unless it relies on other components of hibernate. However, with reflection, we can implement the functionality we want to do with generics.

The first is the interface:

Package Com.sms.dao.base;import Java.util.list;public interface basedao<t> {public void Add (T entity) throws exception;public void Delete (T entity) throws exception;public void Update (T entity) throws Exception;public T FindByID (in Teger ID) throws exception;/* * Get a list of pagesize from startIndex start size */public list<t> getpagelist (int startIndex, int page Size) throws exception;/* * Get total */public long Getamount ();}

Then the implementation class:

Package Com.sms.dao.base.impl;import Java.lang.reflect.parameterizedtype;import Java.util.list;import Javax.annotation.resource;import Org.hibernate.session;import Org.hibernate.sessionfactory;import Com.sms.dao.base.basedao;public class Basedaoimpl<t> implements basedao<t> {private class<t> Entityclass;private String hql; @Resourceprivate sessionfactory sessionfactory;public Session getsession () {return Sessionfactory.getcurrentsession ();} @SuppressWarnings ("unchecked") public Basedaoimpl () {//Gets the class object of the generic passed class by Reflection This.entityclass = (class<t>) (( Parameterizedtype) This.getclass (). Getgenericsuperclass ()). Getactualtypearguments () [0];THIS.HQL = "from" + This.entityClass.getName ();} @Overridepublic void Add (Object entity) {this.getsession (). Save (entity); @Overridepublic void Delete (Object entity) {this.getsession (). Delete (entity);} @Overridepublic void Update (Object entity) {this.getsession (). Update (entity);} @Overridepublic T FindByID (Integer id) {@SuppressWarnings ("uncheckEd ") T result = (T) this.getsession (). get (Entityclass,id); return result;} @Overridepublic list<t> getpagelist (int startIndex, int pageSize) {//TODO auto-generated method Stub@suppresswarnings ("unchecked") list<t> List = This.getsession (). CreateQuery (HQL). Setfirstresult ( StartIndex). Setmaxresults (pageSize). List (); System.out.println (HQL); return list;} @Overridepublic long Getamount () {String sql = "SELECT COUNT (*) from" + this.entityClass.getName (); Long Count = (long) th Is.getsession (). CreateQuery (SQL). Uniqueresult (); return count;}}

Universal interface is completed, we use, as long as the inheritance of Basedaoimp can achieve the most basic additions and deletions to check.

For example, the grade in the Student management system:

The interfaces are:

Package Com.sms.dao;import Com.sms.dao.base.basedao;import Com.sms.entity.gradeentity;public interface GradeDao Extends basedao<gradeentity>{}

Implementation class:

Package Com.sms.dao.impl;import Org.springframework.stereotype.component;import Com.sms.dao.gradedao;import Com.sms.dao.base.impl.basedaoimpl;import com.sms.entity.GradeEntity; @Componentpublic class Gradedaoimpl extends Basedaoimpl<gradeentity> implements gradedao{}

This way, Gradedaoimpl can achieve the most basic function of adding and removing and changing the search.

The design of Basedao and its implementation class based on Hibernate