indextag.java

用jbuilder写的源程序

/**
 * Copyright 2003-2006 the original author or authors. 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.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;

    private String displayCount;

    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 = 1;
        if (count > 0) {
            currentPage = (start / count) + 1;
        }
        
        if ((displayCount == null) || (displayCount.length() == 0))
              this.displayCount = "5";  //default 5
        int dispCount = Integer.parseInt(displayCount);
        int lo = currentPage - dispCount;
        if (lo <= 0) {
            lo = 1;
        }
        int hi = currentPage + dispCount;

        // 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("\" class=\"paginator_href\" 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++;
        }
        
        if (currentPage <= numPages){
            buf.append(" ... ");
            buf.append("<a href=\"").append(url);
            buf.append("&start=");
            buf.append(((numPages - 1) * count));
            buf.append("\" class=\"paginator_href\" title=\"Go to the last page\">");
            buf.append(numPages);
        }

        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);

    }

    /**
     * @return Returns the displayCount.
     */
    public String getDisplayCount() {
        return displayCount;
    }

    /**
     * @param displayCount The displayCount to set.
     */
    public void setDisplayCount(String displayCount) {
        this.displayCount = displayCount;
    }
}