indextag.java

Java/J2EE框架Jdon-Framework系统的Sample

/**
 * Copyright 2005 Jdon.com
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

package com.jdon.strutsutil.taglib;

import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;


public class IndexTag extends TagSupport {

  private boolean disp = false;

  public int doStartTag() throws JspException {

    String dispStrs = (String) pageContext.getAttribute(MPageTag.DISP);
    if ( (dispStrs != null) && (!dispStrs.equals(""))) {
      if (dispStrs.equals("on"))
        disp = true;
      else if (dispStrs.equals("off"))
        disp = false;
    }


    String startStrs = (String) pageContext.getAttribute(MPageTag.START);
    int start = Integer.parseInt(startStrs);
    String url = (String) pageContext.getAttribute(MPageTag.URLNAME);
    String countStrs = (String) pageContext.getAttribute(MPageTag.COUNT);
    int count = Integer.parseInt(countStrs);

    String allCountStrs = (String) pageContext.getAttribute(MPageTag.ALLCOUNT);
    int allCount = Integer.parseInt(allCountStrs);

    StringBuffer buf = new StringBuffer(100);

    int numPages = 0;
    if (allCount != count) {
      numPages = (int) Math.ceil( (double) allCount / (double) count);
    } else {
      numPages = 1;
    }

    // Calculate the starting point & end points (the count of pages to display)
    // 5表示，前后显示数字5个
    int currentPage = (start / count) + 1;
    int lo = currentPage - 5;
    if (lo <= 0) {
      lo = 1;
    }
    int hi = currentPage + 5;

    // print out a link to the first page if we're beyond that page
    if (lo > 2) {
      buf.append("<a href=\"").append(url);
      buf.append(
          "\" title=\"Go to the first page\">1</a> ... ");
    }

    // Print the page numbers before the current page
    while (lo < currentPage) {
      buf.append("<a href=\"").append(url);
      buf.append("&start=");
      buf.append( ( (lo - 1) * count));
      buf.append("\" class=\"paginator_href\">");
      buf.append("<b>");
      buf.append(lo);
      buf.append("</b></a>&nbsp;");
      lo++;
    }

    // Print the current page
    buf.append("<b><span class=\"paginator_currentPage\">");
    buf.append(currentPage);
    buf.append("</span></b>");

    currentPage++;

    // Print page numbers after the current page
    while ( (currentPage <= hi) && (currentPage <= numPages)) {
      buf.append("&nbsp;");
      buf.append("<a href=\"").append(url);
      buf.append("&start=");
      buf.append( ( (currentPage - 1) * count));
      buf.append("\" class=\"paginator_href\">");
      buf.append("<b>");
      buf.append(currentPage);
      buf.append("</b></a>");
      currentPage++;
    }

    HttpServletResponse response =
        (HttpServletResponse) pageContext.getResponse();
    JspWriter writer = pageContext.getOut();
    try {
     if (disp)
        writer.print(buf.toString());
    } catch (IOException e) {
      throw new JspException("PrevTag error");
    }

    return (EVAL_BODY_INCLUDE);

  }

  /**
   * Render the end of the hyperlink.
   *
   * @exception JspException if a JSP exception has occurred
   */
  public int doEndTag() throws JspException {

    return (EVAL_PAGE);

  }

}