第六章自定义标签

最新推荐文章于 2025-03-13 09:54:04 发布

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本文介绍了如何实现并使用自定义标签和自定义便签处理类来创建网页布局和输出内容，包括标签的配置、使用方法及在实际页面中的应用案例。

tdTag.java

package com.msit.tag;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
/**
* 输出内容的自定义标签
* @author Administrator
*
*/

public class tdTag extends TagSupport {

private String type="div"; //输出类型

public String getType() {
return type;
}

public void setType(String type) {
this.type = type;
}

@Override //带@是注解
public int doStartTag() throws JspException {
  //创建输出对象
  JspWriter out=pageContext.getOut();
  try {
   if(type.equals("table")){
    out.print("<table border=1>");

    for(int i=0;i<5;i++){
     out.print("<tr>");
     out.print("<td>标输出表格</td>");
     out.print("</tr>");
    }
    out.print("</table>");
   }else if(type.equals("div")) {
    for(int i=0;i<5;i++){
    out.print("<div style='background-color: #fff;width: 180px;height: 35px'>");
    out.print("<font color='#fff'>输出DIV</font>");
    out.print("</div>");
   }
  }
  } catch (Exception e) {
   e.printStackTrace();
  }
  return SKIP_BODY; //SKIP 跳过或忽略
}

@Override
public int doEndTag() throws JspException {

  return EVAL_PAGE; //EVAL 要评估和计算
}
}

ptd.tld

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

<jsp-config>
   <taglib>
   <taglib-uri>http://com.msit.jsp/tag/ptd</taglib-uri>
   <taglib-location>/WEB-INF/ptd.tld</taglib-location>
</taglib>

</jsp-config>
<login-config>
<auth-method>BASIC</auth-method>
</login-config>
</web-app>

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://com.msit.jsp/tag/ptd" prefix="pt" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
    <base href="<%=basePath%>">

    <title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">

</head>

<body>

      调用自定义标签 <br>
      设置属性：<pt:ptd type="table" />
     <hr>
     <pt:ptd/>
</body>
</html>

MyTagPrint.java

package com.msit.tag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
/**
* 定义第一个输出内容的自定义便签处理类
* @author Administrator
*
*/
public class MyTagPrint extends TagSupport {

//输出的类型
private String type; //table | ul
private int count; //输出次数
private String context="Tag Context!!!"; //输出内容

public int getCount() {
return count;
}

public void setCount(int count) {
this.count = count;
}

public String getContext() {
return context;
}

public void setContext(String context) {
this.context = context;
}

public String getType() {
return type;
}

public void setType(String type) {
this.type = type;
}

@Override
public int doStartTag() throws JspException {
//创建处处对象
JspWriter out= pageContext.getOut();
try {
   if(type.equals("table")){
   out.print("<table border=1>");
   //循环的是行
   for(int i=0;i<count;i++){
    out.print("<tr>");
   out.print("<td>"+context+"</td><td>"+context+"</td>");
   out.print("</tr>");
   }
   out.print("</table>");
   }else if(type.equals("ul")){
    out.print("<ul>");
    for(int i=0;i<count;i++){
     out.print("<li>"+context+"</li>");
    }
    out.print("</ul>");
   }else{
    out.print("Hello Tag !!!!!");
   }
} catch (IOException e) {
   e.printStackTrace();
}
return SKIP_BODY; //SKIP 跳过或忽略
}

@Override
public int doEndTag() throws JspException {
return EVAL_PAGE; //评估或处理
}

}

myprint.tld

<?xml version="1.0" encoding="UTF-8"?>
<taglib version="2.0" 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 web-jsptaglibrary_2_0.xsd">
<tlib-version>1.0</tlib-version>
<short-name>pt</short-name>
<uri>/myprint</uri>
<tag>
<name>myprint</name>

<tag-class>com.msit.tag.MyTagPrint</tag-class>
<body-content>empty</body-content>

<attribute>
   
   <description>值可以输入table或者ul</description>
   
   <name>type</name>
   
   <required>true</required>
   <rtexprvalue>false</rtexprvalue>
   
   <type>java.lang.String</type>
</attribute>
<attribute>
   <description>输出次数</description>
   <name>count</name>
   <required>true</required>
   <rtexprvalue>false</rtexprvalue>
   <type>java.lang.Integer</type>
</attribute>
<attribute>
   <description>输出内容</description>
   <name>context</name>
   <rtexprvalue>false</rtexprvalue>
   <type>java.lang.String</type>
</attribute>
</tag>
</taglib>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

<jsp-config>

<taglib>
   
   <taglib-uri>/msit/myprint</taglib-uri>
   
   <taglib-location>/WEB-INF/myprint.tld</taglib-location>
</taglib>

</jsp-config>
<login-config>
<auth-method>BASIC</auth-method>
</login-config>
</web-app>

index.html

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="/msit/myprint" prefix="p" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>