Struts2中URL处理

墨蓝 2022-07-13 14:56 119阅读 0赞

在Struts中，碰到一个奇怪的现象对于一下两个URL可以访问到同一个Action,

> 链接：
> 
> [http://localhost:8081/operation/operator/quotetask/operator/quotetask/queryByTaskId.do?quoteTaskId=][http_localhost_8081_operation_operator_quotetask_operator_quotetask_queryByTaskId.do_quoteTaskId]
> 
> [http://localhost:8081/operation/operator/quotetask/queryByTaskId.do?quoteTaskId=][http_localhost_8081_operation_operator_quotetask_queryByTaskId.do_quoteTaskId]

在好奇心的驱使下，查看了Struts对于URL的处理源码，在Struts中，主要是需要通过URL找到对应的ActionMapping设置，也就是在Struts.xml中配置的action，其寻找过程如下：  
1. 在web.xml中，配置了.do结尾的请求，都会被struts的`org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter`过滤器过滤。  
2. 在StrutsPrepareAndExecuteFilter中的doFilter中，执行寻找ActionMapping，并执行对应的action方法逻辑

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
    
            HttpServletRequest request = (HttpServletRequest) req;
            HttpServletResponse response = (HttpServletResponse) res;
    
            try {
                if (excludedPatterns != null && prepare.isUrlExcluded(request, excludedPatterns)) {
                    chain.doFilter(request, response);
                } else {
                    prepare.setEncodingAndLocale(request, response);
                    // 创建Struts值栈ValueStack
                    prepare.createActionContext(request, response);
                    // 设置当前分发工具类Dispatcher到当前线程中
                    prepare.assignDispatcherToThread();
                    request = prepare.wrapRequest(request);
                    // 寻找相应的ActionMapping
                    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);
            }
        }

1.  在PrepareOperations.findActionMapping中的逻辑

public ActionMapping findActionMapping(HttpServletRequest request, HttpServletResponse response, boolean forceLookup) {
            ActionMapping mapping = (ActionMapping) request.getAttribute(STRUTS_ACTION_MAPPING_KEY);
            if (mapping == null || forceLookup) {
                try {
                    mapping = dispatcher.getContainer().getInstance(ActionMapper.class).getMapping(request, dispatcher.getConfigurationManager());
                    if (mapping != null) {
                        request.setAttribute(STRUTS_ACTION_MAPPING_KEY, mapping);
                    }
                } catch (Exception ex) {
                    dispatcher.sendError(request, response, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, ex);
                }
            }
    
            return mapping;
        }

1.  最后处理URL的地方在DefaultActionMapper.parseNameAndNamespace中

protected void parseNameAndNamespace(String uri, ActionMapping mapping, ConfigurationManager configManager) {
            String namespace, name;
            int lastSlash = uri.lastIndexOf("/");
            if (lastSlash == -1) {
                namespace = "";
                name = uri;
            } else if (lastSlash == 0) {
                // ww-1046, assume it is the root namespace, it will fallback to
                // default
                // namespace anyway if not found in root namespace.
                namespace = "/";
                name = uri.substring(lastSlash + 1);
            } else if (alwaysSelectFullNamespace) {
                // Simply select the namespace as everything before the last slash
                namespace = uri.substring(0, lastSlash);
                name = uri.substring(lastSlash + 1);
            } else {
                // Try to find the namespace in those defined, defaulting to ""
                Configuration config = configManager.getConfiguration();
                String prefix = uri.substring(0, lastSlash);
                namespace = "";
                boolean rootAvailable = false;
                // Find the longest matching namespace, defaulting to the default
                //找到对应的namespace(operator/quotetask)
                for (PackageConfig cfg : config.getPackageConfigs().values()) {
                    String ns = cfg.getNamespace();
                    if (ns != null && prefix.startsWith(ns) && (prefix.length() == ns.length() || prefix.charAt(ns.length()) == '/')) {
                        if (ns.length() > namespace.length()) {
                            namespace = ns;
                        }
                    }
                    if ("/".equals(ns)) {
                        rootAvailable = true;
                    }
                 }
                  // 找到对应的namspace,并用uri中，去除namespace,用于获取对应的action名字
                name = uri.substring(namespace.length() + 1);
    
                // Still none found, use root namespace if found
                if (rootAvailable && "".equals(namespace)) {
                    namespace = "/";
                }
            }
            // 以上两个URL之所以能访问到同一个action， 关键在此处， 通过前面去掉namespace后，最后获得两个actionName为： operator/quotetask/queryByTaskId 与 /queryByTaskId .在以下代码中，直接获取最后一个"/"后的串，则都获得queryByTaskId.并找到对应的ActionMapping
            if (!allowSlashesInActionNames) {
                int pos = name.lastIndexOf('/');
                if (pos > -1 && pos < name.length() - 1) {
                    name = name.substring(pos + 1);
                }
            }
    
            mapping.setNamespace(namespace);
            mapping.setName(cleanupActionName(name));
        }

### 总结: 在struts中，对与URL的处理，是直接忽略了namespace 与 actionName之间的字符串的。无论是 operator/quotetask/queryByTaskId， operator/quotetask/operator/quotetask/queryByTaskId， 还是operator/quotetask/operator/quotetask/operator/quotetask/queryByTaskId最后获取到的actionMapping都是 namespace: operator/quotetask, actionName: queryByTaskId ###

[http_localhost_8081_operation_operator_quotetask_operator_quotetask_queryByTaskId.do_quoteTaskId]: http://localhost:8081/operation/operator/quotetask/operator/quotetask/queryByTaskId.do?quoteTaskId=
[http_localhost_8081_operation_operator_quotetask_queryByTaskId.do_quoteTaskId]: http://localhost:8081/operation/operator/quotetask/queryByTaskId.do?quoteTaskId=