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  • 小峰servlet/jsp（5）jsp自定义标签

    一、自定义标签helloworld：

    二、自定义有属性的标签：

    HelloWorldTag.java:继承TagSupport:

     1 package com.java1234.tag;
 2 
 3 import java.io.IOException;
 4 
 5 import javax.servlet.jsp.JspException;
 6 import javax.servlet.jsp.JspWriter;
 7 import javax.servlet.jsp.tagext.TagSupport;
 8 
 9 public class HelloWorldTag extends TagSupport{
10         
11     private static final long serialVersionUID = 1L;
12     
13     private String name;
14     
15     public String getName() {
16         return name;
17     }
18 
19     public void setName(String name) {
20         this.name = name;
21     }
22 
23     @Override
24     public int doStartTag() throws JspException {
25         JspWriter out=this.pageContext.getOut();
26         try {
27             out.println(name + "自定义标签你好！");
28         } catch (IOException e) {
29             e.printStackTrace();
30         }
31         return TagSupport.SKIP_BODY; // 直接结束标签
32     }
33 }
    View Code

    java1234.tld描述文件：存放在/WEB-INF/java1234.tld

    tld文件：专门是用来识别标签；标签库描述文件；在jsp页面引入，找到标签处理类；

     1 <?xml version="1.0" encoding="UTF-8" ?>
 2 
 3 <taglib xmlns="http://java.sun.com/xml/ns/javaee"
 4     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 5     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
 6     version="2.1">
 7     <tlib-version>1.0</tlib-version>
 8     <short-name>java1234Tag</short-name>
 9     
10     <tag>
11         <name>helloWorld</name>
12         <tag-class>com.java1234.tag.HelloWorldTag</tag-class>
13         <!-- 标签体 -->
14         <body-content>empty</body-content>
15         <attribute>
16             <name>name</name>
17             <required>true</required>  <!-- required true必须要写的属性 -->
18             <rtexprvalue>true</rtexprvalue> <!-- 是否支持el表达式 true支持 -->
19         </attribute>
20     </tag>
21     
22 </taglib>
    View Code

    helloWorldTag.jsp:

     1 <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
 2 <%@ taglib prefix="java1234" uri="/WEB-INF/java1234.tld" %>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10     <java1234:helloWorld name="JspServlet屌炸天"/>
11 </body>
12 </html>
    View Code

    页面输出：

    三、自定义有标签体的标签；

    IterateTag.java:

     1 package com.java1234.tag;
 2 
 3 import java.util.Iterator;
 4 import java.util.List;
 5 
 6 import javax.servlet.jsp.JspException;
 7 import javax.servlet.jsp.tagext.TagSupport;
 8 
 9 public class IterateTag extends TagSupport{
10 
11     private static final long serialVersionUID = 1L;
12     
13     private String var;
14     private String items;
15     private Iterator iter;
16     
17     public String getVar() {
18         return var;
19     }
20 
21     public void setVar(String var) {
22         this.var = var;
23     }
24 
25     public String getItems() {
26         return items;
27     }
28 
29     public void setItems(String items) {
30         this.items = items;
31     }
32 
33     public Iterator getIter() {
34         return iter;
35     }
36 
37     public void setIter(Iterator iter) {
38         this.iter = iter;
39     }
40 
41     @Override
42     public int doStartTag() throws JspException {
43         Object value=this.pageContext.getAttribute(items);
44         if(value!=null && value instanceof List){
45             this.iter=((List)value).iterator();
46             if(iter.hasNext()){
47                 this.pageContext.setAttribute(var, iter.next());
48                 return TagSupport.EVAL_BODY_INCLUDE; //执行标签体
49             }else{
50                 return TagSupport.SKIP_BODY; //退出标签执行
51             }
52         }else{
53             return TagSupport.SKIP_BODY; //退出标签执行
54         }
55     }
56 
57     //标签体执行完的操作
58     @Override
59     public int doAfterBody() throws JspException {
60         if(iter.hasNext()){
61             this.pageContext.setAttribute(var, iter.next());
62             return TagSupport.EVAL_BODY_AGAIN; //再执行一次标签体
63         }else{
64             return TagSupport.SKIP_BODY; //退出标签体执行
65         }
66     }
67 }
    View Code

    标签库描述文件java1234.tld：

     1 <?xml version="1.0" encoding="UTF-8" ?>
 2 
 3 <taglib xmlns="http://java.sun.com/xml/ns/javaee"
 4     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 5     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
 6     version="2.1">
 7     <tlib-version>1.0</tlib-version>
 8     <short-name>java1234Tag</short-name>
 9 
10     <!-- 定义items和var都是必须属性 -->
11     <tag>
12         <name>iterate</name>
13         <tag-class>com.java1234.tag.IterateTag</tag-class>
14         <body-content>JSP</body-content>
15         <attribute>
16             <name>var</name>
17             <required>true</required>
18             <rtexprvalue>true</rtexprvalue>
19         </attribute>
20         <attribute>
21             <name>items</name>
22             <required>true</required>
23             <rtexprvalue>true</rtexprvalue>
24         </attribute>
25     </tag>
26 </taglib>
    View Code

    iterateTag.jsp:

     1 <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
 2 <%@ page import="java.util.*" %>
 3 <%@ taglib prefix="java1234" uri="/WEB-INF/java1234.tld" %>
 4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 5 <html>
 6 <head>
 7 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 8 <title>Insert title here</title>
 9 <%
10     List people=new ArrayList();
11     people.add("王二小");
12     people.add("丝丝光");
13     people.add("草泥马");
14     pageContext.setAttribute("people", people);
15 %>
16 </head>
17 <body>
18 <java1234:iterate items="people" var="p">
19     <h2>${p }</h2>
20 </java1234:iterate>
21 </body>
22 </html>
    View Code

    访问，页面展示：

    四、简单标签：

    IterateSimpleTag.java:

     1 package com.java1234.tag;
 2 
 3 import java.io.IOException;
 4 import java.util.Iterator;
 5 import java.util.List;
 6 
 7 import javax.servlet.jsp.JspException;
 8 import javax.servlet.jsp.tagext.SimpleTagSupport;
 9 import javax.servlet.jsp.tagext.TagSupport;
10 
11 public class IterateSimpleTag extends SimpleTagSupport{
12 
13     private static final long serialVersionUID = 1L;
14     
15     private String var;
16     private String items;
17     
18     public String getVar() {
19         return var;
20     }
21 
22     public void setVar(String var) {
23         this.var = var;
24     }
25 
26     public String getItems() {
27         return items;
28     }
29 
30     public void setItems(String items) {
31         this.items = items;
32     }
33 
34     @Override
35     public void doTag() throws JspException, IOException {
36         Object value=this.getJspContext().getAttribute(items);
37         if(value!=null && value instanceof List){
38             Iterator iter=((List)value).iterator();
39             while(iter.hasNext()){
40                 this.getJspContext().setAttribute(var, iter.next());
41                 this.getJspBody().invoke(null); //响应页面
42             }
43         }
44     }    
45 }
    View Code

    java1234.tld：

     1 <?xml version="1.0" encoding="UTF-8" ?>
 2 
 3 <taglib xmlns="http://java.sun.com/xml/ns/javaee"
 4     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 5     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
 6     version="2.1">
 7     <tlib-version>1.0</tlib-version>
 8     <short-name>java1234Tag</short-name>
 9     
10     <tag>
11         <name>iterate2</name>
12         <tag-class>com.java1234.tag.IterateSimpleTag</tag-class>
13         <body-content>scriptless</body-content>
14         <attribute>
15             <name>var</name>
16             <required>true</required>
17             <rtexprvalue>true</rtexprvalue>
18         </attribute>
19         <attribute>
20             <name>items</name>
21             <required>true</required>
22             <rtexprvalue>true</rtexprvalue>
23         </attribute>
24     </tag>
25 </taglib>
    View Code

    iterateSimpleTag.jsp:

     1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <%@ page import="java.util.*" %>
 4 <%@ taglib prefix="java1234" uri="/WEB-INF/java1234.tld" %>
 5 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 6 <html>
 7 <head>
 8 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 9 <title>Insert title here</title>
10 <%
11     List people=new ArrayList();
12     people.add("王二小2");
13     people.add("丝丝光2");
14     people.add("草泥马2");
15     pageContext.setAttribute("people", people);
16 %>
17 </head>
18 <body>
19 <java1234:iterate2 items="people" var="p">
20     <h2>${p }</h2>
21 </java1234:iterate2>
22 </body>
23 </html>
    View Code
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  • 原文地址：https://www.cnblogs.com/tenWood/p/6505925.html
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