修改Struts2的struts.xml配置文件位置

默认情况下，Struts2的配置文件名称为struts.xml，且该文件放在src根目录下。如下图所示：

如果需要修改struts.xml的位置，例如把struts.xml放到struts2文件夹下，结构如下图所示，该怎么办呢？

Struts2在web.xml中的一般配置如下：

<!-- 配置struts2过滤器：StrutsPrepareAndExecuteFilter -->
<filter>
    <filter-name>struts2</filter-name>
    <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

为了弄清Stuts2是如何加载配置文件的，先查看Struts2的StrutsPrepareAndExecuteFilter类：

package org.apache.struts2.dispatcher.ng.filter;
/**
 * Handles both the preparation and execution phases of the Struts dispatching process.  This filter is better to use
 * when you don't have another filter that needs access to action context information, such as Sitemesh.
 */
public class StrutsPrepareAndExecuteFilter implements StrutsStatics, Filter {
    protected PrepareOperations prepare;
    protected ExecuteOperations execute;
    protected List<Pattern> excludedPatterns = null;

    public void init(FilterConfig filterConfig) throws ServletException {
        InitOperations init = new InitOperations();
        try {
            FilterHostConfig config = new FilterHostConfig(filterConfig);
            init.initLogging(config);
            Dispatcher dispatcher = init.initDispatcher(config);
            init.initStaticContentLoader(config, dispatcher);

            prepare = new PrepareOperations(filterConfig.getServletContext(), dispatcher);
            execute = new ExecuteOperations(filterConfig.getServletContext(), dispatcher);
            this.excludedPatterns = init.buildExcludedPatternsList(dispatcher);

            postInit(dispatcher, filterConfig);
        } finally {
            init.cleanup();
        }

    }

    /**
     * Callback for post initialization
     */
    protected void postInit(Dispatcher dispatcher, FilterConfig filterConfig) {
    }

    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;

        try {
            prepare.setEncodingAndLocale(request, response);
            prepare.createActionContext(request, response);
            prepare.assignDispatcherToThread();
            if ( excludedPatterns != null && prepare.isUrlExcluded(request, excludedPatterns)) {
                chain.doFilter(request, response);
            } else {
                request = prepare.wrapRequest(request);
                ActionMapping mapping = prepare.findActionMapping(request, response, true);
                if (mapping == null) {
                    boolean handled = execute.executeStaticResourceRequest(request, response);
                    if (!handled) {
                        chain.doFilter(request, response);
                    }
                } else {
                    execute.executeAction(request, response, mapping);
                }
            }
        } finally {
            prepare.cleanupRequest(request);
        }
    }

    public void destroy() {
        prepare.cleanupDispatcher();
    }
}

可以看到，有个public void init(FilterConfig filterConfig) throws ServletException { ... } 方法，很明显，这个方法在启动时会被调用，然后加载classes目录下的struts.xml配置文件。配置文件参数名称为filterConfig。因此，我们可以指定Struts2 Filter 的参数，这和指定Servlet参数相同，配置<init-param>即可。配置如下：

<filter>
    <filter-name>struts2</filter-name>
    <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
    <init-param>
        <param-name>filterConfig</param-name>
        <param-value>classpath:struts2/struts.xml</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>struts2</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

这样配置后，就可以正常加载指定的Struts配置文件了。