Struts2中URL处理

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/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);
}
}

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;
}

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