怎么使用Hibernate进行分页
这篇文章主要介绍了怎么使用Hibernate进行分页的相关知识，内容详细易懂，操作简单快捷，具有一定借鉴价值，相信大家阅读完这篇怎么使用Hibernate进行分页文章都会有所收获，下面我们一起来看看吧。
1.什么是分页?
分页是一种将包含多个记录的列表拆分为子列表的技术。例如，您在Google上使用关键字搜索并收到数以万计的结果。但是，每个Google页面只为您显示 10 个结果。其他结果将在下一页显示。
在使用Hibernate的Java应用程序中，一个查询语句可以返回一个记录列表，并且您会问这样一个问题，即如何只获取列表的一部分(从位置N1 到位置N2的记录)，并获取有关总记录的信息和总页数。
休眠与 JPA
Hibernate和JPA是两种相同的技术。如果您了解 Hibernate， 则可以轻松地使用JPA，反之亦然。但是，它们也有一些区别。其中一个区别是Hibernate提供了比JPA更好的分页技术。在本课中，我将指导您使用Hibernate 5的分页技术。请注意，该技术不受JPA支持。
2.使用 Hibernate 进行分页
您需要做的就是创建一个Query对象，并提供page、maxResult、maxNavigationResult 参数来创建一个PaginationResult对象。PaginationResult
是一个实用程序类，可帮助您实现查询并返回适合上述参数的记录列表。
package org.o7planning.tutorial.hibernate.pagination;import java.util.ArrayList;import java.util.List;import org.hibernate.ScrollMode;import org.hibernate.ScrollableResults;import org.hibernate.query.Query;public class PaginationResult<E> { private int totalRecords; private int currentPage; private List<E> list; private int maxResult; private int totalPages; private int maxNavigationPage; private List<Integer> navigationPages; // @page: 1, 2, ..
public PaginationResult(Query<E> query, int page, int maxResult, int maxNavigationPage) { final int pageIndex = page - 1 < 0 ? 0 : page - 1; int fromRecordIndex = pageIndex * maxResult; int maxRecordIndex = fromRecordIndex + maxResult;
ScrollableResults resultScroll = query.scroll(ScrollMode.SCROLL_INSENSITIVE );
List<E> results = new ArrayList<E>(); boolean hasResult = resultScroll.first(); if (hasResult) {
// Scroll to position:
hasResult = resultScroll.scroll(fromRecordIndex); if (hasResult) { do {
E record = (E) resultScroll.get(0);
results.add(record);
} while (resultScroll.next()//
&& resultScroll.getRowNumber() >= fromRecordIndex
&& resultScroll.getRowNumber() < maxRecordIndex);
} // Go to Last record.
resultScroll.last();
}
// Total Records
this.totalRecords = resultScroll.getRowNumber() + 1; this.currentPage = pageIndex + 1; this.list = results; this.maxResult = maxResult; if (this.totalRecords % this.maxResult == 0) { this.totalPages = this.totalRecords / this.maxResult;
} else { this.totalPages = (this.totalRecords / this.maxResult) + 1;
} this.maxNavigationPage = maxNavigationPage; if (maxNavigationPage < totalPages) { this.maxNavigationPage = maxNavigationPage;
}
resultScroll.close(); this.calcNavigationPages();
} private void calcNavigationPages() { this.navigationPages = new ArrayList<Integer>(); int current = this.currentPage > this.totalPages ? this.totalPages : this.currentPage; int begin = current - this.maxNavigationPage / 2; int end = current + this.maxNavigationPage / 2;
// The first page
navigationPages.add(1); if (begin > 2) {
// Using for '...'
navigationPages.add(-1);
} for (int i = begin; i < end; i++) { if (i > 1 && i < this.totalPages) {
navigationPages.add(i);
}
} if (end < this.totalPages - 2) {
// Using for '...'
navigationPages.add(-1);
}
// The last page.
navigationPages.add(this.totalPages);
} public int getTotalPages() { return totalPages;
} public int getTotalRecords() { return totalRecords;
} public int getCurrentPage() { return currentPage;
} public List<E> getList() { return list;
} public int getMaxResult() { return maxResult;
} public List<Integer> getNavigationPages() { return navigationPages;
}
}例子：
package org.o7planning.tutorial.hibernate.entities;
import java.util.Date;import java.util.HashSet;import java.util.Set;
import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.Lob;import javax.persistence.ManyToOne;import javax.persistence.OneToMany;import javax.persistence.Table;import javax.persistence.Temporal;import javax.persistence.TemporalType;import javax.persistence.UniqueConstraint;@Entity@Table(name = "EMPLOYEE", //
uniqueConstraints = { @UniqueConstraint(columnNames = { "EMP_NO" }) })public class Employee { @Id
@Column(name = "EMP_ID") private Long empId;
@Column(name = "EMP_NO", length = 20, nullable = false) private String empNo;
@Column(name = "EMP_NAME", length = 50, nullable = false) private String empName;
@Column(name = "JOB", length = 30, nullable = false) private String job;
@ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "MNG_ID") private Employee manager;
@Column(name = "HIRE_DATE", nullable = false) @Temporal(TemporalType.DATE) private Date hideDate;
@Column(name = "SALARY", nullable = false) private Float salary;
@Lob
@Column(name = "IMAGE", length = Integer.MAX_VALUE, nullable = true) private byte[] image;
@ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "DEPT_ID", nullable = false) private Department department;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "empId") private Set<Employee> employees = new HashSet<Employee>(0);
// Getter & Setter }package org.o7planning.tutorial.hibernate.entities;
import java.util.HashSet;import java.util.Set;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.Id;import javax.persistence.OneToMany;import javax.persistence.Table;import javax.persistence.UniqueConstraint;
@Entity@Table(name = "DEPARTMENT", //
uniqueConstraints = { @UniqueConstraint(columnNames = { "DEPT_NO" }) })public class Department { @Id
@Column(name = "DEPT_ID") private Integer deptId;
@Column(name = "DEPT_NO", length = 20, nullable = false) private String deptNo; @Column(name = "DEPT_NAME", nullable = false) private String deptName;
@Column(name = "LOCATION") private String location;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "department") private Set<Employee> employees = new HashSet<Employee>(0);
public Department() {
}
// Getter & Setter}package org.o7planning.tutorial.hibernate.beans;public class EmployeeInfo { private Long empId; private String empNo; private String empName; private String deptNo; private String deptName; public EmployeeInfo() {
} // This constructor is used by Hibernate Query.
public EmployeeInfo(Long empId, String empNo, String empName, String deptNo, String deptName) { this.empId = empId; this.empNo = empNo; this.empName = empName; this.deptNo = deptNo; this.deptName = deptName;
} // Getter & Setter}例子：
package org.o7planning.tutorial.hibernate.pagination;import java.util.List;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.query.Query;import org.o7planning.tutorial.hibernate.HibernateUtils;import org.o7planning.tutorial.hibernate.entities.Employee;public class PaginationExample1 { public static void main(String[] args) { // Have sessionFactory object...
SessionFactory factory = HibernateUtils.getSessionFactory();
Session session = factory.getCurrentSession();
String sql = "Select e from " + Employee.class.getName() + " e " //
+ " Where e.empId > :empId ";
Query<Employee> query = session.createQuery(sql, Employee.class);
query.setParameter("empId", 100); int page = 1; int maxResult = 20; int maxNavigationResult = 10;
PaginationResult<Employee> result = new PaginationResult<Employee>(query, page, maxResult, maxNavigationResult); // Result:
List<Employee> emps = result.getList(); int totalPages = result.getTotalRecords(); int totalRecords = result.getTotalRecords(); // 1 2 3 4 5 ... 11 12 13
List<Integer> navPages = result.getNavigationPages();
}
}例子：
package org.o7planning.tutorial.hibernate.pagination;import java.util.List;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.query.Query;import org.o7planning.tutorial.hibernate.HibernateUtils;import org.o7planning.tutorial.hibernate.beans.EmployeeInfo;import org.o7planning.tutorial.hibernate.entities.Employee;public class PaginationExample2 { public static void main(String[] args) { // Get sessionFactory object...
SessionFactory factory = HibernateUtils.getSessionFactory();
Session session = factory.getCurrentSession();
String sql = "Select new " + EmployeeInfo.class.getName() //
+ " (e.empId,e.empNo,e.empName,d.deptNo,d.deptName) " //
+ " from " + Employee.class.getName() + " e " //
+ " Join e.department d " //
+ " Order by e.empNo ";
Query<EmployeeInfo> query = session.createQuery(sql, EmployeeInfo.class); int page = 1; int maxResult = 20; int maxNavigationResult = 10;
PaginationResult<EmployeeInfo> result
= new PaginationResult<EmployeeInfo>(query, page, maxResult, maxNavigationResult); // Result:
List<EmployeeInfo> emps = result.getList(); int totalPages = result.getTotalRecords(); int totalRecords = result.getTotalRecords(); // 1 2 3 4 5 ... 11 12 13
List<Integer> navPages = result.getNavigationPages();
}
}以及使用PaginationResult的JSP代码片段的示例 ：
<c:if test="${paginationProducts.totalPages > 1}">
<div class="page-navigator">
<c:forEach items="${paginationProducts.navigationPages}" var = "page">
<c:if test="${page != -1 }">
<a href="productList?page=${page}" class="nav-item">${page}</a>
</c:if>
<c:if test="${page == -1 }">
<span class="nav-item"> ... </span>
</c:if>
</c:forEach>
</div>
</c:if>关于“怎么使用Hibernate进行分页”这篇文章的内容就介绍到这里，感谢各位的阅读！相信大家对“怎么使用Hibernate进行分页”知识都有一定的了解，大家如果还想学习更多知识，欢迎关注蜗牛博客行业资讯频道。
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