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JSP创建自定义标签库

2011-07-03 23:08 302 查看

自定义标签库描述符exampleTags.tld

<?xml version="1.0" encoding="UTF-8"?>
<taglib version="2.1" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd">   <tlib-version>1.0</tlib-version>
  <short-name>example</short-name>
  <description>自定义标签库描述</description>
  <uri>/WEB-INF/tlds/exampleTags</uri>
   <tag>
   <name>iterate</name>
   <tag-class>tags.FreeTag</tag-class>
   </tag>
   <tag>
   <name>time</name>
   <tag-class>tags.DateTag</tag-class>
   </tag>
</taglib>

FreeTag.class

package tags;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
/**
 * 
 * @author jy
 */
public class FreeTag extends TagSupport {
    private int arrayCount = 0;
    private String[] strings = null;
    
    @Override
	public int doStartTag() throws JspException{
		strings = (String[]) pageContext.getAttribute("strings");
                return EVAL_BODY_INCLUDE;
	}
        
    @Override
        public int doAfterBody() throws JspException{
            try {
                pageContext.getOut().print(" "+strings[arrayCount] + "<br>");
            } catch (IOException ex) {
                Logger.getLogger(FreeTag.class.getName()).log(Level.SEVERE, null, ex);
            }
            arrayCount++;
            if(arrayCount >= strings.length){
                return SKIP_BODY;
            }
            return EVAL_BODY_AGAIN;
        }
}

DateTag.class

package tags;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.jsp.tagext.TagSupport;

/**
 *
 * @author jy
 */
public class DateTag extends TagSupport {
    @Override
    public int doEndTag(){
        SimpleDateFormat format = new SimpleDateFormat("HH:mm:ss");
        String time = format.format(new java.util.Date());
        try {
            pageContext.getOut().print(time);
        } catch (IOException ex) {
            Logger.getLogger(DateTag.class.getName()).log(Level.SEVERE, null, ex);
        }
        return EVAL_PAGE;
    }
}

测试文件test.jsp

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@taglib prefix="example" uri="/WEB-INF/tlds/exampleTags.tld" %>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <h1>Hello World!</h1>
        <%
        String[] strings = new String[]{"a","b","c"};
        pageContext.setAttribute("strings", strings);
        %>
        <example:iterate>
            now time:<example:time/>
        </example:iterate>
    </body>
</html>

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