package cn.myic.model;

import java.util.List;

public class Page<E> {
  // 结果集
  private List<E> list;

  // 查询记录总数
  private int totalRecords;

  // 每页多少条记录
  private int pageSize;

  // 第几页
  private int pageNo;
  
  /**
   * @return 总页数
   * */
  public int getTotalPages(){
    return (totalRecords+pageSize-1)/pageSize;
  }
  
  /**
   * 计算当前页开始记录
   * @param pageSize 每页记录数
   * @param currentPage 当前第几页
   * @return 当前页开始记录号
   */
  public int countOffset(int currentPage,int pageSize){
    int offset = pageSize*(currentPage-1);
    return offset;
  }
  
  /**
   * @return 首页
   * */
  public int getTopPageNo(){
    return 1;
  }
  
  /**
   * @return 上一页
   * */
  public int getPreviousPageNo(){
    if(pageNo<=1){
      return 1;
    }
    return pageNo-1;
  }
  
  /**
   * @return 下一页
   * */
  public int getNextPageNo(){
    if(pageNo>=getBottomPageNo()){
      return getBottomPageNo();
    }
    return pageNo+1;
  }
  
  /**
   * @return 尾页
   * */
  public int getBottomPageNo(){
    return getTotalPages();
  }
  
  
  public List<E> getList() {
    return list;
  }

  public void setList(List<E> list) {
    this.list = list;
  }

  public int getTotalRecords() {
    return totalRecords;
  }

  public void setTotalRecords(int totalRecords) {
    this.totalRecords = totalRecords;
  }

  public int getPageSize() {
    return pageSize;
  }

  public void setPageSize(int pageSize) {
    this.pageSize = pageSize;
  }

  public int getPageNo() {
    return pageNo;
  }

  public void setPageNo(int pageNo) {
    this.pageNo = pageNo;
  }

}

/**
   * 分页查询
   * @param hql 查询的条件
   * @param offset 开始记录
   * @param length 一次查询几条记录
   * @return 返回查询记录集合
   */
  @SuppressWarnings("unchecked")
  @Override
  public List<Course> queryForPage(int offset, int length) {
    // TODO Auto-generated method stub
    List<Course> entitylist=null;
    try{
      Query query = getSession().createQuery("from Course");
      query.setFirstResult(offset);
      query.setMaxResults(length);
      entitylist = query.list();
      
    }catch(RuntimeException re){
      throw re;
    }
    
    return entitylist;
  }

/**
   * 分页查询 
   * @param currentPage 当前页号：现在显示的页数
   * @param pageSize 每页显示的记录条数
   * @return 封闭了分页信息(包括记录集list)的Bean
   * */
  @SuppressWarnings("unchecked")
  @Override
  public Page queryForPage(int currentPage,int pageSize) {
    // TODO Auto-generated method stub

    Page page = new Page();    
    //总记录数
    int allRow = courseDao.getAllRowCount();
    //当前页开始记录
    int offset = page.countOffset(currentPage,pageSize); 
    //分页查询结果集
    List<Course> list = courseDao.queryForPage(offset, pageSize); 

    page.setPageNo(currentPage);
    page.setPageSize(pageSize);
    page.setTotalRecords(allRow);
    page.setList(list);
    
    return page;
  }

@RequestMapping(value = "/showAll.do")
  public String findAllCourse(HttpServletRequest request,
      HttpServletResponse response) {
    try {
      String pageNo = request.getParameter("pageNo");
      if (pageNo == null) {
        pageNo = "1";
      }
      Page page = courseService.queryForPage(Integer.valueOf(pageNo), 10);
      request.setAttribute("page", page);
      List<Course> course = page.getList();
      request.setAttribute("courses", course);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return "course/course_list";
  }

<tr>
      <td colspan="6" align="center" bgcolor="#5BA8DE">共${page.totalRecords}条记录 共${page.totalPages}页 当前第${page.pageNo}页<br>
        
        <a href="${path}/course/showAll.do?pageNo=${page.topPageNo }"><input type="button" name="fristPage" value="首页" /></a>
        <c:choose>
         <c:when test="${page.pageNo!=1}">
          
           <a href="${path}/course/showAll.do?pageNo=${page.previousPageNo }"><input type="button" name="previousPage" value="上一页" /></a>
          
         </c:when>
         <c:otherwise>
          
           <input type="button" disabled="disabled" name="previousPage" value="上一页" />
          
         </c:otherwise>
        </c:choose>
        <c:choose>
         <c:when test="${page.pageNo != page.totalPages}">
          <a href="${path}/course/showAll.do?pageNo=${page.nextPageNo }"><input type="button" name="nextPage" value="下一页" /></a>
         </c:when>
         <c:otherwise>
          
           <input type="button" disabled="disabled" name="nextPage" value="下一页" />
          
         </c:otherwise>
        </c:choose>
        <a href="${path}/course/showAll.do?pageNo=${page.bottomPageNo }"><input type="button" name="lastPage" value="尾页" /></a>
      </td>
    </tr>