SiteMesh3整合SpringMVC+FreeMarker

Posted 2020-06-13

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SiteMesh3配置

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

技术分享

SiteMesh3配置

添加maven依赖

<dependency>

    <groupId>org.sitemesh</groupId>

    <artifactId>sitemesh</artifactId>

    <version>3.0.1</version>

</dependency>

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>

配置servlet

<servlet-mapping>

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

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

</servlet-mapping>

添加sitemesh配置文件

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>

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>

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) {
 
    }
} 

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>

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>

技术分享

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);
}