Struts源码研究 - Action-Input属性篇

t"

input="createuser">

<forward name="createusersuccess" path="/jsp/Welcome.jsp"/>

<forward name="createuser" path="/jsp/createuser.jsp"/>

</action>
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从以上的定义可以看出，如果Validate验证出错，Struts应该为我们重定向到input域所定义的uri，即/jsp/createuser.jsp
看起来应该没有问题，再来看看出错信息，如下：
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java.lang.IllegalArgumentException: Path createuser does not start with a "/" character
at org.apache.catalina.core.ApplicationContext.getRequestDispatcher(ApplicationContext.java:1179)
at org.apache.catalina.core.ApplicationContextFacade.getRequestDispatcher(ApplicationContextFacade.java:174)
at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1062)
at org.apache.struts.tiles.TilesRequestProcessor.doForward(TilesRequestProcessor.java:274)
at org.apache.struts.action.RequestProcessor.internalModuleRelativeForward(RequestProcessor.java:1012)
at org.apache.struts.tiles.TilesRequestProcessor.internalModuleRelativeForward(TilesRequestProcessor.java:345)
at org.apache.struts.action.RequestProcessor.processValidate(RequestProcessor.java:980)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:255)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)

。。。以下省略。。。
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出错信息清楚的说明，“createuser”这个path应该以“/”字符开头
为定位这个错误，从以上错误信息，开始打开Struts的源码RequestProcessor.java进行研究，首先来到这一段：
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public class RequestProcessor {

。。。。。。

protected boolean processValidate(HttpServletRequest request,
HttpServletResponse response,
ActionForm form,
ActionMapping mapping)
throws IOException, ServletException {

if (form == null) {
return (true);
}

// Was this request cancelled?
if (request.getAttribute(Globals.CANCEL_KEY) != null) {
if (log.isDebugEnabled()) {
log.debug(" Cancelled transaction, skipping validation");
}
return (true);
}

// Has validation been turned off for this mapping?
if (!mapping.getValidate()) {
return (true);
}

// Call the form bean's validation method
if (log.isDebugEnabled()) {
log.debug(" Validating input form properties");
}
ActionMessages errors = form.validate(mapping, request);
if ((errors == null) || errors.isEmpty()) {
if (log.isTraceEnabled()) {
log.trace(" No errors detected, accepting input");
}
return (true);
}

// Special handling for multipart request
if (form.getMultipartRequestHandler() != null) {
if (log.isTraceEnabled()) {
log.trace(" Rolling back multipart request");
}
form.getMultipartRequestHandler().rollback();
}

// Has an input form been specified for this mapping?
String input = mapping.getInput();
if (input == null) {
if (log.isTraceEnabled()) {
log.trace(" Validation failed but no input form available");
}
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
getInternal().getMessage("noInput",
mapping.getPath()));
return (false);
}

// Save our error messages and return to the input form if possible
if (log.isDebugEnabled()) {
log.debug(" Validation failed, returning to '" + input + "'");
}
request.setAttribute(Globals.ERROR_KEY, errors);

if (moduleConfig.getControllerConfig().getInputForward()) {
ForwardConfig forward = mapping.findForward(input);
processForwardConfig( request, response, forward);
} else {
internalModuleRelativeForward(input, request, response);
}

return (false);

}
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在出错信息中，提到了internalModuleRelativeForward这个方法，所以着重看以上代码的最后几行，可以看到，如果
moduleConfig.getControllerConfig().getInputForward()这个方法返回了false，那么internalModuleRelativeForward
这个方法将被调用。inputForward是什么？ModuleConfig是管理所有配置信息的一个manager类，那么moduleConfig.getControllerConfig()
这个方法返回的肯定是ControllerConfig这个类的一个实例，那么inputForward肯定是ControllerConfig类的一个成员变量了
再看看struts-config.xml，里面有<controller>这个标签，初步猜测ControllerConfig应该是读取这个标签的一个配置类
而<controller>这个标签应该定义了ActionServlet作为Controller的一些行为！
OK，再来看ControllerConfig这个类中有关inputForward这个成员变量的一些代码，如下：
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/**
* <p>Should the <code>input</code> property of {@link ActionConfig}
* instances associated with this module be treated as the
* name of a corresponding {@link ForwardConfig}. A <code>false</code>
* value treats them as a module-relative path (consistent
* with the hard coded behavior of earlier versions of Struts.</p>
*
* @since Struts 1.1
*/
protected boolean inputForward = false;

public boolean getInputForward() {
retur