jsp如何自定义标签(带参数传递)

admin

1. package mytag.tag;
   
2. 
   
3. import java.io.IOException;
   ; D/ i% I3 u- Z9 j
4. import java.text.SimpleDateFormat;
   9 g. F' a( A) D6 m+ [
5. import java.util.Date;
   
6. 
   & z/ \/ a" ]. H! P4 ?7 L
7. import javax.servlet.jsp.JspException;
   & |6 d2 q' T% ]& Z6 `2 t5 i& M
8. import javax.servlet.jsp.JspWriter;
   
9. import javax.servlet.jsp.PageContext;
   
10. import javax.servlet.jsp.tagext.SimpleTagSupport;
    
11. 
    
12. public class DateTag extends SimpleTagSupport{
    
13.     private String quesId;
    
14. @Override
    3 K% b1 v* L& D
15. public void doTag() throws JspException, IOException {
    
16.       String message = "";
    * P/ w- c) \9 T5 d) U1 n
17.   if(quesId.equals("0")){
    
18.    message = "你好";
    
19.   }else{
    
20.    message = "hello";
    / w9 U$ g3 ]3 w& d* c
21.   }
    
22.   out.println(message);
    " w5 r8 a5 l3 y& Z8 K8 {7 |4 |
23. }
    
24. public String getQuesId() {
    
25.   return quesId;
    
26. }
    
27. public void setQuesId(String quesId) {
    . X, N: r& t8 D+ n% |
28.   this.quesId = quesId;
    0 ~- q9 r4 N7 [5 g2 s
29. }
    9 j1 s" c5 p7 j
30. }

复制代码

标签文件：

1. <?xml version="1.0" encoding="UTF-8" ?>
   * x7 D( N7 w" ^6 k5 T7 g4 J& a
2. <taglib xmlns="http://java.sun.com/xml/ns/j2ee"
   
3.         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   
4.         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
   7 n) l8 R; G6 K6 k
5.         version="2.0">
   
6.         <tlib-version>1.2</tlib-version>
   " K9 T3 q- K# ~0 R
7.         <short-name>c1</short-name>
   
8.         <uri>http://www.52itstyle.top/mytag</uri>
   
9.   <tag>
   / z8 V- l, _# k! }
10.                   <name>date</name>
    
11.               <tag-class>tag.myTag</tag-class>
    8 H8 `  l6 A8 h: e& t; i" G
12.               <body-content>empty</body-content>
    & A1 I: D" [3 ^1 W& s/ |( N
13.               <attribute>
    
14.             <name>quesId</name>
    
15.             <required>true</required>
    
16.             <rtexprvalue>true</rtexprvalue>
    0 X) j  g5 B% \% i
17.         </attribute>
    
18.   </tag>
    8 t5 x, Z0 a1 i
19. </taglib>

复制代码

5 ]2 |2 Q& r. }; e把以上文件命名mytag.tld 放到WEB-INF 下面 即可
9 H) C0 T+ X' B/ I. P% `% c9 |8 J===============================
页面加入：
7 P% [. a3 B6 J- s7 M, q  _

1. <%@ page language="java" import="java.util.*" pageEncoding="utf-8" isELIgnored="false"%>
   
2. <%@taglib uri="/WEB-INF/mytag.tld" prefix="c1"%>
   
3. <c1:date quesId="1"/>

复制代码

$ B' m0 _) H: |6 v+ Y

uperの小鬼

报空指针 是怎么回事？