Struts2-Tiles 2.5.2 升级指南和通配符拓展

最近工程从Struts2.3.18升级Struts2.5.2导致相关联的插件都需要升级到相同版本，其中tiles的变化最大。

1、web.xml上

• listener

org.apache.struts2.tiles.StrutsTilesListener

• context-param

新增tiles资源位置定义参数：org.apache.tiles.definition.DefinitionsFactory.DEFINITIONS_CONFIG

2、tiles.xml 资源声明改成使用value指定！！

由：
<definition name="web.standard.layout.witherror" template="layout.jsp">
 <put-attribute name="header">header.jsp</put-attribute
</definition>
改为：
<definition name="web.standard.layout.witherror" template="layout.jsp">
        <put-attribute name="header" value="header.jsp"></put-attribute
    </definition>

3、默认会加载/WEB-INF/tiles.xml

这样tiles升级基本完成。

---

下面介绍自定义tiles资源搜索功能：

从org.apache.struts2.tiles.StrutsTilesInitializer源码：

  @Override
    protected ApplicationContext createTilesApplicationContext(ApplicationContext preliminaryContext) {
        ServletContext servletContext = (ServletContext) preliminaryContext.getContext();

        if (servletContext.getInitParameter(DefinitionsFactory.DEFINITIONS_CONFIG) != null) {
            LOG.trace("Found definitions config in web.xml, using standard Servlet support ....");
            return new ServletApplicationContext(servletContext);
        } else {
            LOG.trace("Initializing Tiles wildcard support ...");
            return new StrutsWildcardServletApplicationContext(servletContext);
        }
    }

上可得知当在web.xml上自定义了tiles的资源文件位置的话使用ServletApplicationContext进行资源文件的查找。但是一般工程都是使用通配符的形式或者使用spring的文件路径定义的方式配置文件，例如：

file:/WEB-INF/tiles.xml,classpath:/com/cml/test/*/resource/.tiles.xml

此时需要自己拓展了，使用spring的ResourcePatternResolver进行资源查找。

1、第一步，自定义listener

public class WildcardTilesListener extends AbstractTilesListener {

    private static final Logger LOG = LogManager.getLogger(WildcardTilesListener.class);

    @Override
    protected TilesInitializer createTilesInitializer() {
        LOG.info("Starting Struts Tiles 3 integration ...");
        return new WildcardInitializer();
    }

}

2、第二步 自定义StrutsTilesInitializer

public class WildcardInitializer extends StrutsTilesInitializer {
    private static final Logger LOG = LogManager.getLogger(WildcardInitializer.class);

    @Override
    protected ApplicationContext createTilesApplicationContext(ApplicationContext preliminaryContext) {
        ServletContext servletContext = (ServletContext) preliminaryContext.getContext();
        return new WildcardApplicationContext(servletContext);
    }

    @Override
    protected AbstractTilesContainerFactory createContainerFactory(ApplicationContext context) {
        LOG.trace("Creating dedicated Struts factory to create Tiles container");
        return new StrutsTilesContainerFactory();
    }

}

将tiles文件搜索的ApplicationContext更改为自定义的WildcardApplicationContext

3、第三步 继承ServletApplicationContext实现通配符资源文件搜索

public class WildcardApplicationContext extends ServletApplicationContext {

    private static final Logger LOG = LogManager.getLogger(StrutsWildcardServletApplicationContext.class);

    private ServletContext context;

    public WildcardApplicationContext(ServletContext context) {
        super(context);
        this.context = context;
    }

    public Collection<ApplicationResource> getResources(String path) {
        Set<ApplicationResource> resources = new HashSet<>();

        if (path.startsWith("/")) {
            LOG.trace("Using ServletContext to load resource {}", path);
            ApplicationResource resource = getResource(path);
            if (resource != null) {
                resources.add(resource);
            }
        }

        try {
            resources.addAll(findResources(path));
        } catch (IOException e) {
            LOG.error("Cannot find resources for [{}]", path, e);
        }

        return resources;
    }

    public ApplicationResource getResource(ApplicationResource base, Locale locale) {
        String localePath = base.getLocalePath(locale);
        if (new File(localePath).exists()) {
            try {
                return new StrutsApplicationResource(URI.create("file://" + localePath).toURL());
            } catch (MalformedURLException e) {
                LOG.warn("Cannot access [{}]", localePath, e);
                return null;
            }
        }
        return null;
    }

    protected Set<ApplicationResource> findResources(String path) throws IOException {
        Set<ApplicationResource> resources = new HashSet<>();

        LOG.trace("Using ResourceFinder to find matches for {}", path);

        Set<URL> matches = find(path);

        LOG.trace("Found resources {} matching pattern {}", matches, path);

        Iterator<URL> it = matches.iterator();
        while (it.hasNext()) {
            resources.add(new StrutsApplicationResource(it.next()));
        }

        LOG.trace("Found resources {} for path {}", resources, path);
        return resources;
    }

    protected Set<URL> find(String patternResource) {

        Set<URL> pathResources = new HashSet<>();

        try {
            ResourcePatternResolver rpResolver = new PathMatchingResourcePatternResolver();

            Resource[] resources = rpResolver.getResources(patternResource);
            // FileSystemResource ClasspathContextResource
            for (Resource resource : resources) {

                URL resourceUrl = null;

                if (resource instanceof UrlResource) {
                    resourceUrl = context.getResource(resource.getFile().toString());
                } else if (resource instanceof ClassPathResource) {
                    ClassPathResource classpathRes = (ClassPathResource) resource;
                    resourceUrl = context.getResource(classpathRes.getPath());
                } else {
                    resourceUrl = resource.getURL();
                }

                if (resourceUrl != null) {
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Adding resource '" + resourceUrl + "' to definitions factory.");
                    }
                    pathResources.add(resourceUrl);
                    // pathResources.put(resourceUrl.toString(), resourceUrl);
                } else {
                    LOG.warn("Unable to find configured definition '" + resource + "'");
                }
            }
        } catch (IOException e) {
            LOG.error("<<<<<find>>>>", e);
        }

        return pathResources;
    }

}

这样就可以使用spring的配置文件路径的方式配置tiles资源文件了，满足通配符。

4、最后一步 在web.xml上配置tiles文件的位置和listener,自动搜索工程resoruce/*.tiles.xml文件

    <context-param>
        <param-name>org.apache.tiles.definition.DefinitionsFactory.DEFINITIONS_CONFIG</param-name>
        <param-value>file:/WEB-INF/tiles.xml,classpath:/com/cml/tile/**/resource/*.tiles.xml</param-value>
    </context-param>

    <listener>
        <listener-class>xxx.x..x.WildcardTilesListener</listener-class>
    </listener>

由此，Struts-Tiles 2.5.2升级配置完成。