pagehelper.java~3~

来自「hibernate+spring的相片上传项目」· JAVA~3~ 代码 · 共 454 行

package org.lenovoAC.Page;

import java.io.File;
import java.io.IOException;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import freemarker.template.Configuration;
import freemarker.template.DefaultObjectWrapper;
import freemarker.template.Template;
import freemarker.template.TemplateException;

/**
 * 分页器助手类
 *
 * @author pure
 *
 */
public class PageHelper
{
  /**
   * 如果需要在分页条上保存一些状态信息，需要用到request对象
   */
  private HttpServletRequest request;

  private HttpSession session;

  public PageHelper(HttpServletRequest request)
  {
    this.request = request;
    this.session = this.request.getSession();
  }

  /**
   * 用于计算用户自定义每页显示记录数
   *
   * @return 每页显示记录数
   */
  public int doCustomPerPage(int defaultPerPage)
  {
    int perPage = defaultPerPage;
    String cUserPerPage = null;
    String cPerPage = ParamUtil.getString(this.request, "perPage", "");
    if (!"".equals(cPerPage))
    {
      this.session.setAttribute("cPerPage", cPerPage);
    }
    cUserPerPage = (String)this.session.getAttribute("cPerPage");
    if (null != cUserPerPage)
    {
      perPage = Integer.parseInt(cUserPerPage);
    }
    return perPage;
  }

  /**
   * 根据模板生成翻页条
   *
   * @param pageObject
   * @return 返回翻页条字符串
   */
  public String getPageBreakStr(Page pageObject)
  {
    // 取分页器参数
    int page = pageObject.getPage();
    int total = pageObject.getTotal();
    int perPage = pageObject.getPerPage();
    int viewPage = pageObject.getViewPage();
    int cNum = pageObject.getCNum();

    /**
     * 计算前、后可见页码起始位置
     */
    int startPage = ( (page - 1) / viewPage) * viewPage + 1;
    int remberStart = 0;

    String contextPath = pageObject.getContextPath();
    String url = contextPath + "/" + pageObject.getUrl();
    String param = pageObject.getParam();
    /**
     * 图片滤镜样式
     */
    String imgStyle = "style=\"filter:gray\"";
    /**
     * 是否翻页可用 首页 上一页 下一页 最后一页 true 可用 false 不可用
     */
    boolean display1 = false;
    boolean display2 = false;
    boolean display3 = false;
    boolean display4 = false;
    /**
     * 是否有url参数
     */
    boolean isHaveParam = false;

    if (null != param && !"".equals(param))
    {
      isHaveParam = true;
    }

    /**
     * 绝对路径
     */
    String realPath = pageObject.getRealPath();
    /**
     * 翻页模板名
     */
    String pageTemplate = pageObject.getPageTemplate();

    /**
     * 计算总页数
     */
    int totalPage = sumPage(total, perPage);
    page = getCpage(total, perPage, page);

    if (totalPage <= 0)
      return "";
    /**
     * 保存当前页码
     */
    this.request.setAttribute("cpage", String.valueOf(page));

    // 计算页数序列(每次显示10个页数)1..10 11..20 21..30 ....
    StringBuffer pageBarBuffer = new StringBuffer();

    StringBuffer prevPageNumStart = new StringBuffer();
    StringBuffer prevPageNumEnd = new StringBuffer();

    StringBuffer nextPageNumStart = new StringBuffer();
    StringBuffer nextPageNumEnd = new StringBuffer();

    /**
     * 是否在前？页和后？页图片上使用样式
     */
    boolean isPrevPageNumStyle = false;
    boolean isNextPageNumStyle = false;

    pageBarBuffer.append("&nbsp;&nbsp;");
    if (startPage > viewPage)
    {
      prevPageNumStart.append("<a href='" + url);
      prevPageNumStart.append("?page=" + (startPage - 1) + "' >");
      if (isHaveParam)
      {
        prevPageNumStart.append("&" + param);
      }
      prevPageNumEnd.append("</a>");
    }
    else
    {
      isPrevPageNumStyle = true;
    }

    /**
     * 分页页码条
     */
    for (remberStart = startPage; remberStart < startPage + viewPage;
         remberStart++)
    {
      if (remberStart == page)
      {
        pageBarBuffer
            .append("<font color=\"red\" face=\"arial,sans-serif\"><b>"
                    + remberStart + "</b></font>&nbsp;");
      }
      else
      {
        if (isHaveParam)
        {
          pageBarBuffer
              .append("<a href=\""
                      + url
                      + "?page="
                      + remberStart
                      + "&"
                      + param
                      +
              "\"><font face=\"arial,sans-serif\" color=\"#000000\"><b>"
                      + remberStart + "</b></font></a>&nbsp;");
        }
        else
        {
          pageBarBuffer
              .append("<a href=\""
                      + url
                      + "?page="
                      + remberStart
                      +
              "\"><font face=\"arial,sans-serif\" color=\"#000000\"><b>"
                      + remberStart + "</b></font></a>&nbsp;");
        }
      }

      if (remberStart == totalPage)
        break;
    }

    if ( (remberStart - startPage) == viewPage)
    {
      nextPageNumStart.append("<a href='" + url);
      nextPageNumStart.append("?page=" + remberStart + "'>");
      if (isHaveParam)
      {
        nextPageNumStart.append("&" + param);
      }
      nextPageNumEnd.append("</a>");
    }
    else
    {
      isNextPageNumStyle = true;
    }

    pageBarBuffer.append("&nbsp;");

    // 首页
    StringBuffer firstPageBuffer = new StringBuffer();
    if (totalPage > 1 && page != 1)
    {
      firstPageBuffer.append(url + "?page=1");
      if (isHaveParam)
      {
        firstPageBuffer.append("&" + param);
      }
      display1 = true;
    }

    // 上一页
    StringBuffer perPageBuffer = new StringBuffer();
    if (page > 1)
    {
      perPageBuffer.append(url + "?page=" + (page - 1));
      if (isHaveParam)
      {
        perPageBuffer.append("&" + param);
      }
      display2 = true;
    }

    // 下一页
    StringBuffer nextPageBuffer = new StringBuffer();
    if (page < totalPage)
    {
      nextPageBuffer.append(url + "?page=" + (page + 1));
      if (isHaveParam)
      {
        nextPageBuffer.append("&" + param);
      }
      display3 = true;
    }

    // 最后一页
    StringBuffer lastPageBuffer = new StringBuffer();
    if (totalPage > 1 && page < totalPage)
    {
      lastPageBuffer.append(url + "?page=" + totalPage);
      if (isHaveParam)
      {
        lastPageBuffer.append("&" + param);
      }
      display4 = true;
    }

    // 每页显示记录数
    StringBuffer numPageBuffer = new StringBuffer();
    numPageBuffer.append("<select name=\"perPage\" ");
    numPageBuffer.append(" onchange=\"");
    numPageBuffer.append(" if(this.options[this.selectedIndex]");
    numPageBuffer.append(".value!=''){");
    numPageBuffer.append(" location='" + url + "?");
    if (isHaveParam)
    {
      numPageBuffer.append(param + "&");
    }
    numPageBuffer.append("page=1");
    numPageBuffer.append("&perPage='+this.options[this.selectedIndex]");
    numPageBuffer.append(".value;}\">");
    for (int i = 1; i <= cNum; i++)
    {
      numPageBuffer.append("<option value=\"" + (i * 10) + "\"");
      if ( (i * 10) == perPage)
      {
        numPageBuffer.append(" selected>" + (i * 10) + "</option>");
      }
      else
      {
        numPageBuffer.append(">" + (i * 10) + "</option>");
      }
    }
    numPageBuffer.append("</select>");

    // 跳转到第几页
    StringBuffer jumpPageBuffer = new StringBuffer();
    jumpPageBuffer.append("<select name=\"pages\"");
    jumpPageBuffer.append(" onchange=\"");
    jumpPageBuffer.append(" if(this.options[this.selectedIndex]");
    jumpPageBuffer.append(".value!=''){location='" + url + "?");
    if (isHaveParam)
    {
      jumpPageBuffer.append(param + "&");
    }
    jumpPageBuffer.append("page='+this.options[this.selectedIndex]");
    jumpPageBuffer.append(".value;}\">");
    for (int i = 1; i <= totalPage; i++)
    {
      jumpPageBuffer.append("<option value=\"" + i + "\"");
      if (i == page)
      {
        jumpPageBuffer.append("selected");
      }
      jumpPageBuffer.append(">" + i + "</option>");
    }
    jumpPageBuffer.append("</select>");

    Configuration cfg = new Configuration();
    Template newsTemplate = null;
    StringWriter out = new StringWriter();
    try
    {
      cfg.setDirectoryForTemplateLoading(new File(realPath
                                                  +
                                                  pageObject.getPageTemplatePath()));
      cfg.setObjectWrapper(new DefaultObjectWrapper());

      /**
       * 因为本项目所有页面均为UTF-8编码，故此采用UTF-8, 如果页面编码为GBK,此处也需要改成GBK
       */
      newsTemplate = cfg.getTemplate(pageTemplate, "UTF-8");

      /**
       * 以下主要是进行数据填充,将数据填充到模型中
       */
      Map root = new HashMap();
      root.put("total", String.valueOf(total));
      root.put("page", String.valueOf(page));
      root.put("allPage", String.valueOf(totalPage));

      if (display1)
      {
        root.put("firstPageStart", "<a href=\""
                 + firstPageBuffer.toString() + "\">");
        root.put("firstPageEnd", "</a>");
        root.put("firstStyle", "");
      }
      else
      {
        root.put("firstStyle", imgStyle);
        root.put("firstPageStart", "");
        root.put("firstPageEnd", "");
      }
      if (display2)
      {
        root.put("prevPageStart", "<a href=\""
                 + perPageBuffer.toString() + "\">");
        root.put("prevPageEnd", "</a>");
        root.put("prevStyle", "");
      }
      else
      {
        root.put("prevStyle", imgStyle);
        root.put("prevPageStart", "");
        root.put("prevPageEnd", "");
      }
      if (display3)
      {
        root.put("nextPageStart", "<a href=\""
                 + nextPageBuffer.toString() + "\">");
        root.put("nextPageEnd", "</a>");
        root.put("nextStyle", "");
      }
      else
      {
        root.put("nextStyle", imgStyle);
        root.put("nextPageStart", "");
        root.put("nextPageEnd", "");
      }
      if (display4)
      {
        root.put("lastPageStart", "<a href=\""
                 + lastPageBuffer.toString() + "\">");
        root.put("lastPageEnd", "</a>");
        root.put("lastStyle", "");
      }
      else
      {
        root.put("lastStyle", imgStyle);
        root.put("lastPageStart", "");
        root.put("lastPageEnd", "");
      }
      if (isPrevPageNumStyle)
      {
        root.put("prevPageNumStyle", imgStyle);
      }
      else
      {
        root.put("prevPageNumStyle", "");
      }
      if (isNextPageNumStyle)
      {
        root.put("nextPageNumStyle", imgStyle);
      }
      else
      {
        root.put("nextPageNumStyle", "");
      }
      root.put("prevPageNumStart", prevPageNumStart.toString());
      root.put("prevPageNumEnd", prevPageNumEnd.toString());
      root.put("nextPageNumStart", nextPageNumStart.toString());
      root.put("nextPageNumEnd", nextPageNumEnd.toString());
      root.put("pagePrevPage", pageBarBuffer.toString());
      root.put("pageBar", pageBarBuffer.toString());
      root.put("numPage", numPageBuffer.toString());
      root.put("jumpPage", jumpPageBuffer.toString());
      try
      {
        newsTemplate.process(root, out);
      }
      catch (TemplateException e)
      {
        e.printStackTrace();
      }

    }
    catch (IOException e)
    {
      e.printStackTrace();
    }
    return out.toString();
  }

  public int sumPage(int total, int perPage)
  {
    int totalPage = (total + perPage - 1) / perPage;
    return totalPage;
  }

  public int getCpage(int total, int perPage, int cPage)
  {
    if (cPage - sumPage(total, perPage) == 1)
    {
      cPage--;
    }

    if (cPage - sumPage(total, perPage) > 1 || cPage < 1)
    {
      cPage = 1;
    }
    return cPage;
  }
}