SSH2 框架下的分页

Posted 2020-08-09 草鸟It

1.设计分页实体（pageBean）

这里我显示的是3-12页的方式：

  1 package cn.itcast.oa.domain;
  2 
  3 import java.util.List;
  4 
  5 /**
  6  * 封装分页信息
  7  * @author zhaoqx
  8  *
  9  */
 10 public class PageBean {
 11     /**从页面提交过来的参数**/
 12     private int currentPage;//----当前页码
 13     private int pageSize;//-------每页显示多少条数据
 14     
 15     /**查询数据库获得**/
 16     private int recordCount;//----总记录数
 17     private List recordList;//页面要显示的数据集合
 18     
 19     /**由上面4个计算获得**/
 20     private int pageCount;//------总页数
 21     private int beginPageIndex;//-开始页码
 22     private int endPageIndex;//---结束页码
 23     
 24     public PageBean() {}
 25     
 26     
 27 
 28     public PageBean(int currentPage, int pageSize, int recordCount,List recordList) {
 29         this.currentPage = currentPage;
 30         this.pageSize = pageSize;
 31         this.recordCount = recordCount;
 32         this.recordList = recordList;
 33         
 34         pageCount = (this.recordCount + this.pageSize - 1) / this.pageSize;//计算页数
 35         
 36         if(pageCount <= 10){
 37             this.beginPageIndex = 1;
 38             this.endPageIndex = this.pageCount;
 39         }else{
 40             this.beginPageIndex = this.currentPage - 4;
 41             this.endPageIndex = this.currentPage + 5;
 42             
 43             if(this.beginPageIndex < 1){
 44                 this.beginPageIndex = 1;
 45                 this.endPageIndex = 10;
 46             }
 47             if(this.endPageIndex > this.pageCount){
 48                 this.endPageIndex = this.pageCount;
 49                 this.beginPageIndex = this.endPageIndex - 9;
 50             }
 51         }
 52     }
 53 
 54     public int getCurrentPage() {
 55         return currentPage;
 56     }
 57 
 58     public void setCurrentPage(int currentPage) {
 59         this.currentPage = currentPage;
 60     }
 61 
 62     public int getPageCount() {
 63         return pageCount;
 64     }
 65 
 66     public void setPageCount(int pageCount) {
 67         this.pageCount = pageCount;
 68     }
 69 
 70     public int getPageSize() {
 71         return pageSize;
 72     }
 73 
 74     public void setPageSize(int pageSize) {
 75         this.pageSize = pageSize;
 76     }
 77 
 78     public int getRecordCount() {
 79         return recordCount;
 80     }
 81 
 82     public void setRecordCount(int recordCount) {
 83         this.recordCount = recordCount;
 84     }
 85 
 86     public int getBeginPageIndex() {
 87         return beginPageIndex;
 88     }
 89 
 90     public void setBeginPageIndex(int beginPageIndex) {
 91         this.beginPageIndex = beginPageIndex;
 92     }
 93 
 94     public int getEndPageIndex() {
 95         return endPageIndex;
 96     }
 97 
 98     public void setEndPageIndex(int endPageIndex) {
 99         this.endPageIndex = endPageIndex;
100     }
101 
102     public List getRecordList() {
103         return recordList;
104     }
105 
106     public void setRecordList(List recordList) {
107         this.recordList = recordList;
108     }
109 }

 

2.在action里面调用

 1 package cn.itcast.oa.action;
 2 
 3 import java.util.Date;
 4 import java.util.List;
 5 
 6 import org.springframework.context.annotation.Scope;
 7 import org.springframework.stereotype.Controller;
 8 
 9 import cn.itcast.oa.base.BaseAction;
10 import cn.itcast.oa.domain.Forum;
11 import cn.itcast.oa.domain.PageBean;
12 import cn.itcast.oa.domain.Reply;
13 import cn.itcast.oa.domain.Topic;
14 import cn.itcast.oa.utils.HQLHelper;
15 
16 /**
17  * 主题操作
18  * @author zhaoqx
19  *
20  */
21 @Controller
22 @Scope("prototype")
23 public class TopicAction extends BaseAction<Topic>{
24     private Long forumId;//属性驱动，版块id    
25     
26     /**
27      * 显示单个主题（回复列表）
28      */
29     public String show(){
30         //根据id查询主题
31         Topic topic = topicService.getById(model.getId());
32         getValueStack().push(topic);
33         
34         //根据主题查询对应的回复列表        
35         HQLHelper hh = new HQLHelper(Reply.class);
36         hh.addWhere("o.topic = ?", model);
37         hh.addOrderBy("o.postTime", true);
38         PageBean pb = replyService.getPageBean(hh,currentPage);
39         getValueStack().push(pb);
40         
41         return "show";
42     }
43 
44     public void setForumId(Long forumId) {
45         this.forumId = forumId;
46     }
47 
48     public Long getForumId() {
49         return forumId;
50     }
51 }

 

这里的currentPage 是在baseAction里面定义的  代码如下：

1 protected int currentPage = 1;//属性驱动，当前页码
2 
3     public int getCurrentPage() {
4         return currentPage;
5     }
6 
7     public void setCurrentPage(int currentPage) {
8         this.currentPage = currentPage;
9     }

 

 

3.在BaseDaoImpl 里面写

  1 package cn.itcast.oa.base;
  2 
  3 import java.lang.reflect.ParameterizedType;
  4 import java.lang.reflect.Type;
  5 import java.util.List;
  6 
  7 import javax.annotation.Resource;
  8 
  9 import org.hibernate.Query;
 10 import org.hibernate.Session;
 11 import org.hibernate.SessionFactory;
 12 import org.springframework.orm.hibernate3.HibernateTemplate;
 13 
 14 import cn.itcast.oa.domain.Book;
 15 import cn.itcast.oa.domain.PageBean;
 16 import cn.itcast.oa.utils.HQLHelper;
 17 /**
 18  * 通用Dao实现
 19  * @author zhaoqx
 20  *
 21  * @param <T>
 22  */
 23 @SuppressWarnings("unchecked")
 24 public class BaseDaoImpl<T> implements IBaseDao<T> {
 25     @Resource
 26     private SessionFactory sessionFactory;
 27     
 28     private Class<T> clazz;
 29     
 30     public BaseDaoImpl() {
 31         //获得实体类型
 32         ParameterizedType genericSuperclass = (ParameterizedType) this.getClass().getGenericSuperclass();//获得真正的父类
 33         Type[] types = genericSuperclass.getActualTypeArguments();
 34         clazz = (Class<T>) types[0];
 35     }
 36     
 37     public void save(T entity) {
 38         getSession().save(entity);
 39     }
 40     
 41     public void delete(Long id) {
 42         getSession().delete(getSession().get(clazz, id));
 43     }
 44     
 45     public void update(T entity) {
 46         getSession().update(entity);
 47     }
 48 
 49     public List<T> findAll() {
 50         String hql = "FROM " + clazz.getSimpleName();
 51         return getSession().createQuery(hql).list();
 52     }
 53 
 54     public T getById(Long id) {
 55         return (T) getSession().get(clazz, id);
 56     }
 57     
 58     public List<T> getByIds(Long[] ids) {
 59         String hql = "FROM " + clazz.getSimpleName() + " WHERE id in (:ids)";
 60         Query query = getSession().createQuery(hql);
 61         query.setParameterList("ids", ids);//一次赋值多个
 62         return query.list();
 63     }
 64     
 65     public Session getSession(){
 66         return sessionFactory.getCurrentSession();
 67     }
 68 
 69     /**
 70      * 公共分页
 71      */
 72     public PageBean getPageBean(HQLHelper hh, int currentPage) {
 73         int pageSize = 5;
 74         int firstResult = (currentPage - 1) * pageSize;
 75         String listHQL = hh.getListHQL();
 76         String countHQL = hh.getCountHQL();
 77         List<Object> args = hh.getArgs();
 78         
 79         Query query = this.getSession().createQuery(listHQL);
 80         if(args != null && args.size() > 0){
 81             int index = 0;
 82             for(Object o : args){
 83                 query.setParameter(index++, o);
 84             }
 85         }
 86         query.setFirstResult(firstResult);
 87         query.setMaxResults(pageSize);
 88         List recordList = query.list();
 89         
 90         query = this.getSession().createQuery(countHQL);
 91         if(args != null && args.size() > 0){
 92             int index = 0;
 93             for(Object o : args){
 94                 query.setParameter(index++, o);
 95             }
 96         }
 97         Long recordCount = (Long) query.uniqueResult();
 98         
 99         return new PageBean(currentPage, pageSize, recordCount.intValue(), recordList);
100     }
101 
102 }

 

4.最后还有一个工具类:

 1 package cn.itcast.oa.utils;
 2 
 3 import java.util.ArrayList;
 4 import java.util.List;
 5 
 6 /**
 7  * 辅助生成HQL语句的工具类
 8  * @author zhaoqx
 9  *
10  */
11 public class HQLHelper {
12     private String fromStr;//FROM 子句
13     private String whereStr = "";//WHERE 子句
14     private String orderByStr = "";//ORDER BY 子句
15     
16     private List<Object> args = new ArrayList<Object>();//封装HQL中对应的参数信息
17     
18     public HQLHelper() {}
19     
20     /**
21      * 通过构造方法拼接FROM 子句
22      * @param clazz
23      */
24     public HQLHelper(Class clazz) {
25         this.fromStr = "FROM " + clazz.getSimpleName() + " o ";
26     }
27     
28     /**
29      * 拼接WHERE 子句
30      * @param condition
31      * @param args
32      */
33     public void addWhere(String condition,Object...args){//o.name = ?
34         if(this.whereStr.length()==0){
35             //第一次拼接WHERE子句
36             this.whereStr = " WHERE " + condition;
37         }else{
38             //不是第一次拼接WHERE子句
39             this.whereStr += " AND " + condition;
40         }
41         if(args != null && args.length > 0){
42             //封装参数
43             for(Object o : args){
44                 this.args.add(o);
45             }
46         }
47     }
48     
49     /**
50      * 拼接ORDER BY 子句
51      * @param orderBy
52      * @param asc
53      */
54     public void addOrderBy(String orderBy , boolean asc){
55         if(this.orderByStr.length() == 0){
56             //第一次拼接ORDER BY 子句
57             this.orderByStr = " ORDER BY " + orderBy + (asc ? " ASC " : " DESC ");
58         }else{
59             //不是第一次拼接ORDER BY 子句
60             this.orderByStr += ", " + orderBy + (asc ? " ASC " : " DESC ");
61         }
62     }
63     
64     /**
65      * 获取查询List集合的HQL语句
66      * @return
67      */
68     public String getListHQL(){
69         return this.fromStr + this.whereStr + this.orderByStr;
70     }
71     
72     /**
73      * 获取查询统计记录数的HQL
74      * @param args
75      */
76     public String getCountHQL(){
77         return "SELECT COUNT(*) " + this.fromStr + this.whereStr;
78     }
79 
80     public void setArgs(List<Object> args) {
81         this.args = args;
82     }
83 
84     public List<Object> getArgs() {
85         return args;
86     }
87     
88 }

好了，这样一个通用的分页就完成啦。。。