Principle of struct2

1. stay web.xml Filter in FilterDispatcher, bring strcut2 The system can take over the entire system request

2.struct2 Request from the page action The goal of , And then in struts.xml The corresponding processing class of the target is found in the configuration file of

3.2 At the same time, the framework uses the fields in the form to automatically assign values to those instantiated in the target processing class bean object

4. The return result obtained by the framework according to the processing class , lookup struts.xml The file corresponds to result Label content , Return to the specific page .

summary , The framework is to get control through the filter , And then in strcut.xml Help you link the submission form page with the class that processes and returns the processing results .（ The parameters of the form attribute and the processing result return page are through , Form attributes are the same as those in the class ！）

To make a form processing program, the general steps are , First ： Create a form page , Create a separate class , Create a result page . The three data interact through the same attribute name ！. Last , To configure strut.xml The document links the three ！ The rest is strut2 Help you finish ！

Focus on , because struts After becoming a filter , If you initialize normally as shown , It will make all pages of the whole website inaccessible , Tips 404 error ！ especially struts6.0.0 This problem is more likely to occur after ！

Often cause 404 The reason for the mistake is ：

1.<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" 
"http://struts.apache.org/dtds/struts-2.3.dtd"> Wrong version ,struts6.0.0 In the future, we will put 2.3 Change to 2.5. Otherwise, you must prompt 404.

2. The imported package is incomplete . In addition to those bags on the Internet ,commons-text-1.8.jar This package must contain .

struts6.0.0 Unwanted xwork-core.jar package

3.<filter>
        <filter-name>struts2</filter-name>
        <filter-class>org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter</filter-class>
    </filter>

struts6.0.0 in , The filter path changes , No, ng.filter It is filter

summary , Everyone may have the same problem , But the reason is strange , Learn to base on eclipse Prompt to solve the fastest .