Jsp自定义标签：
1.继承SimpleTagSupport,重写doTag()。
2.在WEB-INF/ 下配置**.tld文件
3.Jsp页面引入自定义标签:<%@ taglib uri="***" prefix="s"%>
自定义标签demo实现：在jsp页面将对象存入pageContext.setAttribute(),使用标签输出该对象的所有方法，成员变量及值。
TestTag.java:
package mytag;
import java.io.IOException;
import java.io.Writer;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class TestTag extends SimpleTagSupport{
private String obj;//带属性标签必须为每个属性提供对应的 setter 和 getter 方法
public String getObj() {
return obj;
}
public void setObj(String obj) {
this.obj = obj;
}
public void doTag() throws IOException{
Writer out = getJspContext().getOut();
Object object=(Object)getJspContext().getAttribute(obj);
Class<?> c=object.getClass();
Field fields[]=c.getDeclaredFields();
for(Field f:fields ){
f.setAccessible(true);//私有成员也能访问
try {
out.write(f.getName()+":"+f.get(object)+"</br>");
} catch (IllegalArgumentException | IllegalAccessException e) {
e.printStackTrace();
}
}
Method methods[]=c.getMethods();
for(Method m:methods){
out.write(m.toString()+"</br>");
}
}
}
mytaglib.tld:
<?xml version="1.0" encoding="ISO-8859-1" ?>
<!DOCTYPE taglib
PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
"http://java.sun.com/j2ee/dtd/web-jsptaglibrary_1_2.dtd">
<taglib> <tlib-version>1.0</tlib-version>
<jsp-version>1.2</jsp-version>
<short-name>mytaglib</short-name>
<uri>/mytaglib</uri>
<tag>
<!-- 定义标签名 -->
<name>info</name>
<!-- 定义标签处理类 -->
<tag-class>mytag.TestTag</tag-class>
<!-- 定义标签体为空 -->
<body-content>empty</body-content>
<!-- 配置标签属性:driver -->
<attribute>
<name>obj</name>
<required>true</required>
<fragment>true</fragment>
</attribute>
</tag>
</taglib>
test.jsp:
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import="mytag.User,java.util.*" %>
<%@ taglib uri="/mytaglib" prefix="s" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
pageContext.setAttribute("date", new Date());
%>
<b><s:hello/></b>
<b><s:info obj="date"/></b>
</body>
</html
