sitemesh3是一个页面布局框架，可以是你的页面无缝的嵌入到一个整体页面中，从而是你的页面看起来风格是一致的，所有的一切从这里开始
ConfigurableSiteMeshFilter
public void init(FilterConfig filterConfig) throws ServletException { this.filterConfig = filterConfig; configProperties = getConfigProperties(filterConfig); autoReload = getAutoReload(); logger.config("Auto reloading " + (autoReload ? "enabled" : "disabled"));
synchronized (configLock) { deployNewFilter(setup()); } initialized = true; }
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { if (!initialized) { throw new ServletException(getClass().getName() + ".init(FilterConfig) was not called"); } reloadIfNecessary(); filter.doFilter(servletRequest, servletResponse, filterChain); }
sitemesh3是从该filter开始的，首先看init(),了解它初始化过程
我们看到configProperties = getConfigProperties(filterConfig);，是filter的配置信息，autoReload = getAutoReload(); 查看配置文件是否需要自动重加载，默认是开启的。从后边可以知道它是通过对比sitemesh3.xml的最后修改时间来确定是不是需要加载的
这些只是准备工作，关键点在 deployNewFilter(setup()); ,也就是setup方法中
setup会创建一个filter，当执行到doFilter（） ,内部实际执行的就是filter.doFilter(),到这里就可以肯定所有核心内容都在这个filter中，包括init和filter的过程，首先我们看init的过程，了解它都需要那些东西，然后再看doFilter中的内容，来决定我们怎么改进它。
protected Filter setup() throws ServletException { ObjectFactory objectFactory = getObjectFactory(); SiteMeshFilterBuilder builder = new SiteMeshFilterBuilder();
new PropertiesFilterConfigurator(objectFactory, configProperties) .configureFilter(builder);
new XmlFilterConfigurator(getObjectFactory(), loadConfigXml(filterConfig, getConfigFileName())) .configureFilter(builder);
applyCustomConfiguration(builder);
return builder.create(); }
一行一行的来讲ObjectFactory里面其实只有一行代码 return class.forName(className) ,就是为类生成对象，同时隔离到那些exception。
builder 这个类很重要，所有的配置信息都会存到里面，PropertiesFilterConfigurator 这行是将web.xml 中sitemeshfilter中的配置信息，存放到builder中
下面一行是将sitemesh3.xml中的配置信息，存放到builder中。
applyCustomConfiguration(builder);这行是为了通过java编码的方式来配置filter
配置信息有 exclude, decorate, minetype,content-processor,tag-rule-bundle
exclude 是不需要装饰，decorate是需要装饰的， minetype 是默认返回的页面类型， content-processor 是自定义的页面内容处理器，tag-rule-bundle 是自定义的标签，如<sitemesh:write/>等。
这里就可以看清楚sitemesh配置有三种方式 1,filter,2,sitemesh.xml, 3 java硬编码 ，混合使用的话，优先级从搞到低
下面我们去详细看看builder中有什么东西
Filter create() { return new SiteMeshFilter( getSelector(), getContentProcessor(), getDecoratorSelector()); } 看到没有一个热乎的filter出炉了， 用到了builder的三个属性， selector 选择器，contentProcessor 内容处理器,decoratorSelector 装饰选择器 我们继续深入：selector 是关于mineType决定是否拦截 , contentProcessor 是解析标签的 ，decoratorSelector 是关于装饰页面和被装饰页面的关系 好了，初始化过程基本就看完了，接下来就到正餐时间了，从上面我们没有看到更多的默认配置信息， 下一步就是这里filter.doFilter() ，等把这个过程理完了，然后再把代码通读一遍就能明白了
SiteMeshFilter.class FilterConfig filterConfig = getFilterConfig(); if (filterConfig == null) { // TODO: Is this really necessary? Can we survive without init() being called? throw new ServletException(getClass().getName() + ".init() has not been called."); } HttpServletRequest request = (HttpServletRequest) servletRequest; HttpServletResponse response = (HttpServletResponse) servletResponse; ServletContext servletContext = filterConfig.getServletContext();
if (!selector.shouldBufferForRequest(request)) { // Optimization: If the content doesn't need to be buffered, // skip the rest of this filter. filterChain.doFilter(request, response); return; }
if (containerTweaks.shouldAutoCreateSession()) { // Some containers (such as Tomcat 4) will not allow sessions // to be created in the decorator. (i.e after the // response has been committed). request.getSession(true); }
try {
// The main work. bufferAndPostProcess(filterChain, request, response, selector);
} catch (IllegalStateException e) { // Some containers (such as WebLogic) throw an IllegalStateException when an error page is served. // It may be ok to ignore this. However, for safety it is propegated if possible. if (!containerTweaks.shouldIgnoreIllegalStateExceptionOnErrorPage()) { throw e; } } catch (RuntimeException e) { if (containerTweaks.shouldLogUnhandledExceptions()) { // Some containers (such as Tomcat 4) swallow RuntimeExceptions in filters. servletContext.log("Unhandled exception occurred whilst decorating page", e); } throw e; }
。。。。 filterChain.doFilter(wrapRequest(request), responseBuffer); CharBuffer buffer = responseBuffer.getBuffer(); // If content was buffered, post-process it. boolean processed = false; if (buffer != null && !responseBuffer.bufferingWasDisabled()) { processed = postProcess(responseBuffer.getContentType(), buffer, request, response, metaData); }
if (!response.isCommitted()) { responseBuffer.preCommit(); }
// If no decoratoes applied, and we have some buffered content, write the original. if (buffer != null && !processed) { writeOriginal(response, buffer, responseBuffer); }
WebAppContext context = createContext(contentType, request, response, metaData); Content content = contentProcessor.build(buffer, context); if (content == null) { return false; } String[] decoratorPaths = decoratorSelector.selectDecoratorPaths(content, context); for (String decoratorPath : decoratorPaths) { content = context.decorate(decoratorPath, content); }
if (content == null) { return false; }
content.getData().writeValueTo(response.getWriter()); return true;
首先用rule规则将内容解析一遍，再找到要装饰的页面，然后用dispatch去解析，取得内容后，用context将被装饰页面和装饰页面一起解析
接下来我们着重看看一下 contentProccesor.build() 和 context.decorate() 和 context.build() 即可就先到这里吧，自己一边看一边写挺累的