jsp如何自定义标签(带参数传递)
package mytag.tag;import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class DateTag extends SimpleTagSupport{
private String quesId;
@Override
public void doTag() throws JspException, IOException {
String message = "";
if(quesId.equals("0")){
message = "你好";
}else{
message = "hello";
}
out.println(message);
}
public String getQuesId() {
return quesId;
}
public void setQuesId(String quesId) {
this.quesId = quesId;
}
}标签文件：
<?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">
<tlib-version>1.2</tlib-version>
<short-name>c1</short-name>
<uri>http://www.52itstyle.top/mytag</uri>
<tag>
<name>date</name>
<tag-class>tag.myTag</tag-class>
<body-content>empty</body-content>
<attribute>
<name>quesId</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
</taglib>
把以上文件命名mytag.tld 放到WEB-INF 下面 即可
===============================
页面加入：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8" isELIgnored="false"%>
<%@taglib uri="/WEB-INF/mytag.tld" prefix="c1"%>
<c1:date quesId="1"/>
报空指针 是怎么回事？
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