自定义标签 排序标签

package com.toolkit.taglibs;

import java.net.URLEncoder;
import java.util.Iterator;
import java.util.Map;

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.Tag;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts2.components.Component;
import org.apache.struts2.views.jsp.ComponentTagSupport;

import com.opensymphony.xwork2.util.ValueStack;

/**
 * 
 * @author JohnCheng
 * @version 1.0.0
 * @since 2010-01-19
 */
public class SortTag extends ComponentTagSupport {

	/**
	 * 
	 */
	private static final long serialVersionUID = -4137098453204513199L;

	public static Log log = LogFactory.getLog(SortTag.class);
	
	private final static String DESC = "desc";
	
	private final static String ASC = "asc";

	private String field;
	
	private String action = "";
	
	private boolean isAsc = false;
	
	private boolean matched = false;
	
	private JspWriter writer;

	public int doStartTag() throws JspException {

		StringBuffer sb = new StringBuffer(action);//current page
		
        sb.append("?field=");
        
        sb.append( field );
        
        sb.append("&sort=");
        
        String sort = pageContext.getRequest().getParameter("sort");
        
        isAsc = ASC.equalsIgnoreCase(sort);
        
        sb.append(isAsc ? DESC : ASC);
        
        matched = field.equalsIgnoreCase( pageContext.getRequest().getParameter("field") );
        
		Map parameters = pageContext.getRequest().getParameterMap();
		
        Iterator iterator = parameters.keySet().iterator();
        
        HttpServletRequest req = (HttpServletRequest)pageContext.getRequest();
        
        
        try{
		        while (iterator.hasNext()) {
		            String key = (String) iterator.next();
		            if("field".equals(key) || "sort".equals(key) || "random".equals(key)){
		            	continue;
		            }
		            sb.append("&")
		            .append(key)
		            .append("=")
		            .append(URLEncoder.encode( ((String[])parameters.get(key))[0],"UTF-8"));
		        }
        }catch(Exception ex){
        	log.error(ex);
        }
        writer = pageContext.getOut();
        try {
        	writer.write("<a href=\""+sb.toString() + "\" style=\"text-decoration: none;color: #FFFFFF; font-size: 12px;font-weight: bold;\" title=\"点击排序\">" );
        }catch(Exception ex ){
        	log.error(ex);
        }
		return Tag.EVAL_BODY_INCLUDE;
	}

@Override
public int doEndTag() throws JspException {
	String root = ((HttpServletRequest)pageContext.getRequest()).getContextPath();
	try{
	if(matched){
		if(isAsc){
			this.writer.write(" <img border='0' src='"+root+"/images/asc.gif'/>");
		}else{
			writer.write(" <img border='0' src='"+root+"/images/desc.gif'/>");
		}
	}
	writer.write("</a>");
	}catch(Exception ex){
		log.error(ex);
	}
	return Tag.EVAL_BODY_INCLUDE;
}

	public String getAction() {
		return action;
	}

	public void setAction(String action) {
		this.action = action;
	}

	public String getField() {
		return field;
	}

	public void setField(String field) {
		this.field = field;
	}

	@Override
	public Component getBean(ValueStack arg0, HttpServletRequest arg1,
			HttpServletResponse arg2) {
		
		return null;
	}


}

这个写得比较差，懒得改了，已经可以用了。