jsp中有这样一段代码需要移除
// String ip = request.getRemoteAddr(); // out.print(ip);
首先我们可以写一个java类继承TagSupport类，并覆盖dostartTag方法
public class ViewIPTag extends TagSupport {
@Override
public int doStartTag() throws JspException {
HttpServletRequest request = (HttpServletRequest) this.pageContext.getRequest();
JspWriter out = this.pageContext.getOut();
String ip = request.getRemoteAddr();
try {
out.print(ip);
} catch (IOException e) {
throw new RuntimeException(e);
}
return super.doStartTag();
}
}
在WEB-INF目录下写一个tld文件来描述处理器
<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<description>A tag library exercising SimpleTag handlers.</description>
<tlib-version>1.0</tlib-version>
<short-name>itcast</short-name>
<uri>http://www.itcast.cn</uri>
<tag>
<name>viewIP</name>
<tag-class>cn.itcast.web.tag.ViewIPTag</tag-class>
<body-content>empty</body-content>
</tag>
</taglib>
jsp页面为
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://www.itcast.cn" prefix="ip"%>
<!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>display your ip</title>
</head>
<body>
your ip is: <ip:viewIP/>
<%
// String ip = request.getRemoteAddr();
// out.print(ip);
%>
</body>
</html>
运行后可以看见输出