自定义JSP TagLib实战-优快云博客

我的第一个taglib

taglib的好处:封装了那些重复使用的jsp,html,javascript代码,可以作为一个工具实现重用.

taglib分三个部分: java,tld,及jsp

java :

package com.davic.test.taglib;

import java.text.DecimalFormat;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyContent;
import javax.servlet.jsp.tagext.BodyTagSupport;

public class MetersToFeet extends BodyTagSupport { //1.重点,必须继承BodyTagSupport
private int precision = 2;

@Override
public int doAfterBody() throws JspException {// 重载方法(有多个方法,这是其中一个而已)
// TODO Auto-generated method stub
BodyContent body = this.getBodyContent(); // 得到body内容
try {
//实现标签逻辑
float meters = Float.valueOf(body.getString()).floatValue();
DecimalFormat df = new DecimalFormat();
df.setMaximumFractionDigits(this.precision);
//response 回去主体
body.getEnclosingWriter().println(df.format(meters * 3.28));

} catch (Exception e) {
System.out.println("you have input invalid parameters");
} finally {
body = null;
}
return this.EVAL_PAGE;
}

public int getPrecision() {
return precision;
}

public void setPrecision(int precision) {
this.precision = precision;
}

}

tld:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd"> 
<taglib>
<tlib-version>2.2</tlib-version> 
<jsp-version>1.2</jsp-version> 
<short-name>******Taglib</short-name> 
<uri>/marryfive</uri> 
<display-name>*****Taglib</display-name> 
<description><![CDATA[Marryfive JSP Taglib]]></description> 
<tag>
<name>m2f</name>
<tag-class>com.davic.test.taglib.MetersToFeet</tag-class> 
<body-content>jsp</body-content>
<attribute>
<name>precision</name>
<required>false</required> 
</attribute>
</tag>
</taglib>

jsp:
<%@ taglib uri="/Web-INF/metric.tld" prefix="metric"%>
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
<html><head>
<title>"ding ni ge fei"</title>
</head>
<body>
<h1>testing metric tags</h1>
30 meters is <metric:m2f>30</metric:m2f> feet <br> //使用例子
<metric:m2f precision="4">37.98345</metric:m2f>fett<br>
</body>
</html>

然后在发布上web 服务器

打http://localhost:[your port]/[web-app]/[jsp.name]