简介

sitemesh应用Decorator模式，用filter截取request和response,把页面组件head,content,banner结合为一个完整的视图。通常我们都是用include标签在每个jsp页面中来不断的包含各种header, stylesheet, scripts and footer，在sitemesh的帮助下，我们不用在每个jsp页面中写这些代码了，方面项目的维护。

image.png

引入jar包

<!-- maven -->
<dependency>
  <groupId>opensymphony</groupId>
  <artifactId>sitemesh</artifactId>
  <version>2.4.2</version>
</dependency>

配置filter

在web.xml按如下代码配置filter，对应url返回的view都会被sitemesh处理。

<!-- sitemesh -->
<filter>
    <filter-name>sitemesh</filter-name>
    <filter-class>com.opensymphony.module.sitemesh.filter.PageFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>sitemesh</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

配置decorator

在WEB-INF目录下新建decorators.xml，defaultdir定义装饰器所在的根目录。

<?xml version="1.0" encoding="UTF-8"?>
<decorators defaultdir="/WEB-INF/layout/">
    <!-- 不被装饰的url -->
    <excludes>
        <pattern>/static/*</pattern>
    </excludes>

    <!-- 装饰器定义 -->
    <decorator name="default" page="base.jsp">
        <pattern>*</pattern>
        <pattern>/example</pattern>
        <pattern>/example/example</pattern>
        <pattern>/example/*</pattern>
        <pattern>/**/example</pattern>
    </decorator>
</decorators>

引入decorator标签

decorator标签有两种引入方式：

1.在web.xml文件中配置taglib

<taglib>
  <taglib-uri>sitemesh-decorator</taglib-uri>
  <taglib-location>/WEB-INF/sitemesh-decorator.tld</taglib-location>
</taglib>
<taglib>
  <taglib-uri>sitemesh-page</taglib-uri>
  <taglib-location>/WEB-INF/sitemesh-page.tld</taglib-location>
</taglib>

在对应的taglib-location下复制tld文件（可在jar包里找到）。

image.png

装饰器里引入taglib

<%@ taglib uri="sitemesh-decorator" prefix="decorator"%>
<%@ taglib uri="sitemesh-page" prefix="page"%>

uri与taglib-uri对应

2.快速引入

<%@ taglib uri="http://www.opensymphony.com/sitemesh/decorator" prefix="decorator"%>

装饰器

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="http://www.opensymphony.com/sitemesh/decorator" prefix="decorator"%>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title><decorator:title default="首页"/>-example</title>
    <decorator:head/>
</head>
<body>
    <decorator:body/>
</body>
</html>

被装饰页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<html>
<head>
<title>welcome!</title>
</head>
<body>
    <p>welcome to example !</p>
</body>
</html>