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 }
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>
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>
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 }
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>
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>
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 }
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>
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>
时间： 2024-12-17 20:11:16