SiteMesh3整合SpringMVC+FreeMarker

• SiteMesh3配置
  • 添加maven依赖
  • 添加filter
  • 配置servlet
  • 添加sitemesh配置文件 
  • decorator示例
  • SpringMVC、FreeMarker配置（404问题处理）
  • decorate源码

SiteMesh3文档 http://wiki.sitemesh.org/wiki/pages/viewpage.action?pageId=1081348

重新搭建项目偶然发现SiteMesh有了新版本SiteMesh3，本着用新不用旧原则果断升级，多少遇了点坑，顺便记录下

SiteMesh3配置

1. 添加maven依赖

   <dependency>
       <groupId>org.sitemesh</groupId>
       <artifactId>sitemesh</artifactId>
       <version>3.0.1</version>
   </dependency>

2. 添加filter

   在web.xml中添加filter

   <filter>
       <filter-name>sitemesh</filter-name>
       <filter-class>org.sitemesh.config.ConfigurableSiteMeshFilter</filter-class>
   </filter>
   <filter-mapping>
       <filter-name>sitemesh</filter-name>
       <url-pattern>/*</url-pattern>
   </filter-mapping>

3. 配置servlet

   <servlet-mapping>
       <servlet-name>default</servlet-name>
       <url-pattern>*.ftl</url-pattern>
   </servlet-mapping>

4. 添加sitemesh配置文件 

   1. 添加配置文件 sitemesh3.xml
      默认配置文件路径为：/WEB-INF/sitemesh3.xml 

      sitemesh3.xml

      <sitemesh>
          <!--
          By default, SiteMesh will only intercept responses that set the Content-Type HTTP header to text/html
          This can be altered to allow SiteMesh to intercept responses for other types.
          默认 SiteMesh 只对HTTP响应头中Content-Type为 text/html 的类型进行拦截和装饰，若需要处理其它mime类型需要自行添加配置
          -->
          <mime-type>text/html</mime-type>
          <!--
          Map default decorator. This shall be applied to all paths if no other paths match.
          配置装饰器，仅设置decorator参数时表示为默认的装饰器，当没有任何路径被匹配时会使用默认装饰器装配
           -->
          <mapping decorator="/WEB-INF/decorators/decorator.ftl"/>
          <!--对不同的路径指定特定的装饰器-->
          <!--<mapping path="/admin/*" decorator="/WEB-INF/decorators/admin-decorator.ftl"/>-->
          <!--
          Alternative convention. This is more verbose but allows multiple decorators to be applied to a single path.
          对同一路径可以同时使用多个装饰器
          -->
          <mapping>
              <path>/category/*</path>
              <decorator>/WEB-INF/decorators/common-decorator.ftl</decorator>
              <decorator>/WEB-INF/decorators/menu-decorator.ftl</decorator>
              <decorator>/WEB-INF/decorators/category-decorator.ftl</decorator>
          </mapping>
          <!--
          Exclude path from decoration.
          排除路径，只需将exclue设置为true即可
          -->
          <mapping path="/static/*" exclue="true"/>
          <!--
          An advanced feature of SiteMesh is the ability to define custom rules that manipulate tags on a page.
          These are classes that implement org.sitemesh.content.tagrules.TagRuleBundle.
          默认SiteMesh仅支持title、head、meta、body等tag,可以自定义tag，实现TagRuleBundle接口即可
          -->
          <content-processor>
              <tag-rule-bundle class="com.sankuai.shangchao.util.HtmlTagRuleBundle"/>
          </content-processor>
      </sitemesh>

      
      

   2. 修改配置文件路径
      默认配置文件路径为：/WEB-INF/sitemesh3.xml 若需要修改配置文件路径需要在filter里配置configFile参数 

      <filter>
          <filter-name>sitemesh</filter-name>
          <filter-class>org.sitemesh.config.ConfigurableSiteMeshFilter</filter-class>
          <init-param>
              <param-name>configFile</param-name>
              <param-value>/WEB-INF/sitemesh3.xml</param-value>
          </init-param>
      </filter>

      
      

   3. 自定义tag

      HtmlTagRuleBundle.java

      import org.sitemesh.SiteMeshContext;
      import org.sitemesh.content.ContentProperty;
      import org.sitemesh.content.tagrules.TagRuleBundle;
      import org.sitemesh.content.tagrules.html.ExportTagToContentRule;
      import org.sitemesh.tagprocessor.State;
       
      /**
       * Description: FootTagRuleBundle
       * Author: liuzhao
       * Create: 2015-08-22 09:21
       */
      public class HtmlTagRuleBundle implements TagRuleBundle {
          @Override
          public void install(State defaultState, ContentProperty contentProperty, SiteMeshContext siteMeshContext) {
              defaultState.addRule("foot", new ExportTagToContentRule(siteMeshContext, contentProperty.getChild("foot"), false));
          }
       
          @Override
          public void cleanUp(State defaultState, ContentProperty contentProperty, SiteMeshContext siteMeshContext) {
       
          }
      } 

      
      

5. decorator示例

   decorator配置页面布局layout，对应的tag会被进行装饰替换

   decorator.ftl

   <!DOCTYPE html>

   <html>

   <head>

       <title>

           <sitemesh:write property="title"/>

       </title>

       <sitemesh:write property='head'/>

   </head>

   <body>

   <h1>啦拉拉，我是卖报的小行家</h1>

   <sitemesh:write property='body'/>

   <sitemesh:write property="foot"/>

   </body>

   </html>

6. SpringMVC、FreeMarker配置（404问题处理）

   sitemesh3是完全独立的，不和任何框架进行偶合，因此SpringMVC、FreeMarker配置完全不需要考虑sitemesh3的兼容问题
   在加载装饰器的时候，会出现404问题，可能的原因是找不到ftl文件的解析器，所以需要配置下ftl使用默认的Servlet解析，在web.xml中添加如下配置

   <servlet-mapping>

       <servlet-name>default</servlet-name>

       <url-pattern>*.ftl</url-pattern>

   </servlet-mapping>

1. decorate源码

   @Override

   protected boolean postProcess(String contentType, CharBuffer buffer,

                                 HttpServletRequest request, HttpServletResponse response,

                                 ResponseMetaData metaData)

           throws IOException, ServletException {

       WebAppContext context = createContext(contentType, request, response, metaData);

       Content content = contentProcessor.build(buffer, context);

       if (content == null) {

           return false;

       }

    

       String[] decoratorPaths = decoratorSelector.selectDecoratorPaths(content, context);

       //遍历装饰器进行装饰

       for (String decoratorPath : decoratorPaths) {

           content = context.decorate(decoratorPath, content);

       }

    

       if (content == null) {

           return false;

       }

       try {

           content.getData().writeValueTo(response.getWriter());

       } catch (IllegalStateException ise) {  // If getOutputStream() has already been called

           content.getData().writeValueTo(new PrintStream(response.getOutputStream()));

       }

       return true;

   }

    

   public Content decorate(String decoratorName, Content content) throws IOException {

       if (decoratorName == null) {

           return null;

       }

    

       class CharBufferWriter extends CharArrayWriter {

           public CharBuffer toCharBuffer() {

               return CharBuffer.wrap(this.buf, 0, this.count);

           }

       }

       CharBufferWriter out = new CharBufferWriter();

       decorate(decoratorName, content, out);

    

       CharBuffer decorated = out.toCharBuffer();

    

       Content lastContent = currentContent;

       currentContent = content;

       try {

           return contentProcessor.build(decorated, this);

       } finally {

           currentContent = lastContent;

       }

   }

    

   @Override

   protected void decorate(String decoratorPath, Content content, Writer out) throws IOException {

       HttpServletRequest filterableRequest = new HttpServletRequestFilterable(request);

       // Wrap response so output gets buffered.

       HttpServletResponseBuffer responseBuffer = new HttpServletResponseBuffer(response, metaData, new BasicSelector(new PathMapper<Boolean>(), includeErrorPages) {

           @Override

           public boolean shouldBufferForContentType(String contentType, String mimeType, String encoding) {

               return true; // We know we should buffer.

           }

       });

       responseBuffer.setContentType(response.getContentType()); // Trigger buffering.

    

       // It's possible that this is reentrant, so we need to take a copy

       // of additional request attributes so we can restore them afterwards.

       Object oldContent = request.getAttribute(CONTENT_KEY);

       Object oldContext = request.getAttribute(CONTEXT_KEY);

    

       request.setAttribute(CONTENT_KEY, content);

       request.setAttribute(CONTEXT_KEY, this);

    

       try {

           // Main dispatch.

           dispatch(filterableRequest, responseBuffer, decoratorPath);

    

           // Write out the buffered output.

           CharBuffer buffer = responseBuffer.getBuffer();

           out.append(buffer);

       } catch (ServletException e) {

           //noinspection ThrowableInstanceNeverThrown

           throw (IOException) new IOException("Could not dispatch to decorator").initCause(e);

       } finally {

           // Restore previous state.

           request.setAttribute(CONTENT_KEY, oldContent);

           request.setAttribute(CONTEXT_KEY, oldContext);

       }

   }

    

   protected void dispatch(HttpServletRequest request, HttpServletResponse response, String path)

           throws ServletException, IOException {

       //这里调用加载文件会出现404错误 /WEB-INF/decorators/decorator.ftl

       RequestDispatcher dispatcher = servletContext.getRequestDispatcher(path);

       if (dispatcher == null) {

           throw new ServletException("Not found: " + path);

       }

       dispatcher.forward(request, response);

   }