用Hibernate实现分页查询

 1 package com.entity; 2 /** 3 ?* @author:秦林森 4 ?*/ 5 ?6 import javax.persistence.criteria.CriteriaBuilder; 7 ?8 public class Page { 9 ????/**10 ?????* ?其中currentPage,perPageRows这两个参数是做分页查询必须具备的参数11 ?????* ?原因是：hibernate中的Criteria或则是Query这两个接口：都有setFirstResult(Integer firstResult)12 ?????* ?和setMaxResult(Integer maxResult),13 ?????* ?这里的firstResult就是每页的开始的索引数：14 ?????* ?每页开始的索引数的计算公式是：（currentPage-1）*perPageRows+1,(这是相对索引从1开始的)15 ?????* ?但是Hibernate中的firstResult的索引是从0开始的，所以在hibernate中每页开始的索引数的计算公式是：16 ?????* ?(currentPage-1)*perPageRows+1-1=(currentPge-1)*perPageRows.17 ?????*18 ?????* ?maxResult就是每页能查询的最大记录数：也就是perPageRows.19 ?????*20 ?????* ?Math.ceil(totalRows/perPageRows)==totalPages;//这是根据总记录数和每页的记录数算出总页数的计算公式。21 ?????*/22 ????private Integer currentPage;//当前页23 ????private Integer perPageRows;//每页的记录数24 ????private Integer totalRows;//总记录数：25 ????private Integer totalPages;//总页数：26 ????public Integer getCurrentPage() {27 ????????return currentPage;28 ????}29 30 ????public void setCurrentPage(Integer currentPage) {31 ????????this.currentPage = currentPage;32 ????}33 34 ????public Integer getPerPageRows() {35 ????????return perPageRows;36 ????}37 38 ????public void setPerPageRows(Integer perPageRows) {39 ????????this.perPageRows = perPageRows;40 ????}41 42 ????public Integer getTotalRows() {43 ????????return totalRows;44 ????}45 46 ????public void setTotalRows(Integer totalRows) {47 ????????this.totalRows = totalRows;48 ????}49 50 ????public Integer getTotalPages() {51 ????????return totalPages;52 ????}53 54 ????public void setTotalPages(Integer totalPages) {55 ????????this.totalPages = totalPages;56 ????}57 }

 1 package com.entity; 2 ?3 import javax.persistence.*; 4 ?5 @Entity 6 @Table(name = "EMPLOYEE") 7 public class Employee { 8 ????@Id 9 ????@GeneratedValue(strategy = GenerationType.IDENTITY)10 ????private int id;11 ????@Column(name = "first_name")12 ????private String firstName;13 ????@Column(name = "last_name")14 ????private String lastName;15 ????@Column(name = "salary")16 ????private int salary;17 ????//a constructor with no arguments18 19 20 ????public Employee() {21 ????}22 23 ????public int getId() {24 ????????return id;25 ????}26 27 ????public void setId(int id) {28 ????????this.id = id;29 ????}30 31 ????public String getFirstName() {32 ????????return firstName;33 ????}34 35 ????public void setFirstName(String firstName) {36 ????????this.firstName = firstName;37 ????}38 39 ????public String getLastName() {40 ????????return lastName;41 ????}42 43 ????public void setLastName(String lastName) {44 ????????this.lastName = lastName;45 ????}46 47 ????public int getSalary() {48 ????????return salary;49 ????}50 51 ????public void setSalary(int salary) {52 ????????this.salary = salary;53 ????}54 }

<?xml version=‘1.0‘ encoding=‘utf-8‘?><!DOCTYPE hibernate-configuration PUBLIC ???????"-//Hibernate/Hibernate Configuration DTD//EN" ???????"http://hibernate.sourceforge.net/hibernate-configuration-5.0.dtd"><hibernate-configuration> ???<session-factory> ???????<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> ???????<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property> ???????<property name="hibernate.connection.username">root</property> ???????<property name="hibernate.connection.password">130850a,</property> ???????<property name="hibernate.connection.pool_size">10</property> ???????<property name="show_sql">true</property> ???????<property name="dialect">org.hibernate.dialect.MySQLDialect</property> ???????<property name="hibernate.current_session_context_class">thread</property> ???????<mapping class="com.entity.Employee" /> ???</session-factory></hibernate-configuration>

 1 package com.util; 2 import org.hibernate.SessionFactory; 3 import org.hibernate.boot.Metadata; 4 import org.hibernate.boot.MetadataSources; 5 import org.hibernate.boot.registry.StandardServiceRegistry; 6 import org.hibernate.boot.registry.StandardServiceRegistryBuilder; 7 import org.hibernate.cfg.Configuration; 8 import org.hibernate.service.ServiceRegistry; 9 public class HibernateUtil {10 ????private static final SessionFactory sessionFactory;11 12 ????private static ServiceRegistry serviceRegistry;13 14 ????static {15 ????????try {16 ????????????StandardServiceRegistry standardRegistry =17 ????????????????????new StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build();18 ????????????Metadata metaData =19 ????????????????????new MetadataSources(standardRegistry).getMetadataBuilder().build();20 ????????????sessionFactory = metaData.getSessionFactoryBuilder().build();21 ????????} catch (Throwable th) {22 23 ????????????System.err.println("Enitial SessionFactory creation failed" + th);24 ????????????throw new ExceptionInInitializerError(th);25 26 ????????}27 ????}28 ????public static SessionFactory getSessionFactory() {29 30 ????????return sessionFactory;31 32 ????}33 }

 1 package com.hibDemo; 2 ?3 import com.entity.Employee; 4 import com.entity.Page; 5 import com.util.HibernateUtil; 6 import org.hibernate.Criteria; 7 import org.hibernate.Session; 8 import org.hibernate.SessionFactory; 9 import org.hibernate.Transaction;10 11 import java.util.List;12 13 public class PaginationQuery {14 15 ????public void paginationByCriteria(){16 ????????SessionFactory sessionFactory = HibernateUtil.getSessionFactory();17 ????????Session session = sessionFactory.getCurrentSession();18 ????????Transaction tx=null;19 ????????try {20 ????????????//do some work21 ????????????tx=session.beginTransaction();22 ????????????Page page = new Page();23 ????????????/**24 ?????????????* 假设现在查询的是第一页，每页查询的最大记录数是3.25 ?????????????*/26 ????????????page.setCurrentPage(1);27 ????????????page.setPerPageRows(3);28 ????????????Criteria criteria = session.createCriteria(Employee.class);29 ????????????Integer currentPage = page.getCurrentPage();//得到当前页30 ????????????Integer perPageRows = page.getPerPageRows();//得到每页的记录数：31 ????????????/**32 ?????????????* 在Page类中我已说明了：每页开始的索引数在hibernate中的计算公式是：(currentPage-1)*perPageRows33 ?????????????*/34 ????????????criteria.setFirstResult((currentPage-1)*perPageRows);35 ????????????criteria.setMaxResults(perPageRows);36 ????????????List<Employee> employees = criteria.list();37 ????????????for(Employee employee:employees){38 ????????????????System.out.println("*********************");39 ????????????????System.out.println("id="+employee.getId()+" firstName="+employee.getFirstName()+" lastName="+employee.getLastName());40 ????????????}41 ????????????tx.commit();42 43 ????????} catch (Exception e) {44 ????????????if(tx!=null){45 ????????????????tx.rollback();46 ????????????}47 ????????????e.printStackTrace();48 ????????} finally {49 ????????????session.close();//关闭流，一定要关闭，不然会影响运行速度。50 ????????}51 ????}52 ????public static void main(String[] args) {53 ????????PaginationQuery paginationQuery = new PaginationQuery();54 ????????paginationQuery.paginationByCriteria();55 ????}56 }