jsp自定义嵌套标签

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1.定义标签实现类

ParentTag.java

[java] view plaincopy

import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
public class ParentTag extends TagSupport {
private static final long serialVersionUID = 1L;
private Map<String,String> map = new HashMap<String,String>();
//标签属性id
private String id ;
public String getId(){
return id;
}
public void setId(String id){
this.id = id;
}
//该方法在子标签中调用，给父标签中的map赋值
public void addValue(String key,String value){
map.put(key,value);
}
/**
* doStartTag()方法返回一个整数值，用来决定程序的后续流程。
*　A.Tag.SKIP_BODY：表示标签之间的内容被忽略
*　B.Tag.EVAL_BODY_INCLUDE：表示标签之间的内容被正常执行
*/
public int doStartTag() throws JspException {
JspWriter out = pageContext.getOut();
try {
Set<String> keySet = map.keySet();
Iterator<String> it = keySet.iterator();
while(it.hasNext()){
String key = it.next();
String value = map.get(key);
out.write(key +": <input type='text' name="+key+" value="+value+" /><br>");
}
} catch (IOException e) {
e.printStackTrace();
}
return EVAL_BODY_INCLUDE;
}
/**
* doEndTag：当JSP容器遇到自定义标签的结束标志，就会调用doEndTag()方法。doEndTag()方法也返回一个整数值，用来决定程序后续流程。
　　 * A.Tag.SKIP_PAGE：表示立刻停止执行网页，网页上未处理的静态内容和JSP程序均被忽略任何已有的输出内容立刻返回到客户的浏览器上。
　　 * B.Tag.EVAL_PAGE：表示按照正常的流程继续执行JSP网页
*/
public int doEndTag() throws JspException {
return EVAL_PAGE;
}
}

ChildTag.java

[java] view plaincopy

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class ChildTag extends TagSupport {
private static final long serialVersionUID = 1L;
//定义标签属性key，value
private String key;
private String value;
public String getKey(){
return key;
}
public void setKey(String key){
this.key = key;
}
public String getValue(){
return value;
}
public void setValue(String value){
this.value = value;
}
public int doStartTag() throws JspException {
ParentTag pTag = (ParentTag) this.getParent();
//调用父标签的addValue方法，给父标签中的map赋值
pTag.addValue(key,value);
return EVAL_BODY_INCLUDE;
}
public int doEndTag() throws JspException {
return EVAL_PAGE;
}
}

2.编写nested.tld文件

[xhtml] view plaincopy

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE taglib
PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN"
"http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
<taglib>
<tlib-version>1.0</tlib-version>
<jsp-version>2.0</jsp-version>
<short-name>nest</short-name>
<uri>/nests/nested.tld</uri>
<tag>
<name>parent</name>
<tag-class>tag.nested.ParentTag</tag-class>
<!-- scriptless 主体可以有内容, 而jsp容器会去处理里面的jsp元素, 换句话就是可以是文本, EL表达式,
标准动作甚至另一个自定义标记. -->
<body-content>scriptless</body-content>
<attribute>
<name>id</name>
<required>true</required>
<rtexprvalue>false</rtexprvalue>
</attribute>
</tag>
<tag>
<name>child</name>
<tag-class>tag.nested.ChildTag</tag-class>
<body-content>empty</body-content>
<attribute>
<name>key</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>value</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
</taglib>

3.配置web.xml

[xhtml] view plaincopy

<jsp-config>
<taglib>
<taglib-uri>/nest-tag</taglib-uri>
<taglib-location>/WEB-INF/tlds/nested.tld</taglib-location>
</taglib>
</jsp-config>

4.编写测试网页

nested.jsp

[xhtml] view plaincopy

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="nest" uri="/WEB-INF/tlds/nested.tld" %>
<%@ taglib prefix="n" uri="/nests/nested.tld" %>
<!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>Insert title here</title>
</head>
<body>
<nest:parent id="1">
<nest:child key="key1" value="value1"/>
<nest:child key="key2" value="value2"/>
</nest:parent>
<n:parent id="2">
<n:child key="key3" value="value3"/>
<n:child key="key4" value="value4"/>
</n:parent>
</body>
</html>

至此完成嵌套标签的编写

部署应用，访问nested.jsp就能看到效果了