"Web Development Learning note" STRUCTS2 Action learning Note (i)

1. Org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter Preparation and execution
2.

  <filter-mapping>      <filter-name>struts2</filter-name>      <url-pattern>/*</ Url-pattern>  </filter-mapping>

url-pattern contract cooked to write * *, no need to write *.action
3.

<package name= "Default" namespace= "/" extends= "Struts-default" >     <action name= "Hello" >         < result>         /hello.jsp         </result>     </action>    <span style= "White-space:pre" ></ Span></package>

   Namespace= "/" and the path meaning corresponding to the access;
    /hello.action
    The action was accessed, giving us the result of result;
    The default action can be omitted;
4. Associated structs source code and Java docs
Jar file Right-click->properies->java Source Attachment
    Set source code
        D:/program Files/struts-2.1.6/src/core/src/main/java
    Javadoc documentation
        File:/d:/program files/struts-2.1.6/docs/struts2-core/apidocs/
    To set the XML hint:
        A) window–preferences– search Catalog–add

B) Select key type as URI

c) key:http://struts.apache.org/dtds/struts-2.0.dtd

D) Location: the corresponding DTD file, located in the Struts-core package, unzip open, specify the corresponding position, such as D:/program files/struts-2.1.6 \lib\struts2-core-2.1.6\s Truts-2.0.dtd
5. Structs Operation mechanism
Find the filter Dofilter method , WebApplication, Web. XML, URL------HTTP request--Tomacat, client-side->

  <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>

, reference Struct.xml, find the corresponding action, find corresponding result, feedback result, request Forwad to the destination file

  <package name= "Default" namespace= "/" extends= "Struts-default" ><action name= "index" ><result>/ Index.jsp</result></action> </package>

6, namespace determines the access path of the action, the default is "", you can receive all the path action
Namespace can be written as/, or/xxx, or/xxx/yyy,
The corresponding action access path is/index.action,/xxx/index.action, or/xxx/yyy/index.action.
Namespace it is best to also use a module to name

   <constant name= "Struts.devmode" value= "true"/>    <package name= "front" extends= "Struts-default" Namespace= "/front" >        <action name= "index" >            <result>/Namespace.jsp</result>        < /action>    </package>         <package name= "main" extends= "Struts-default" namespace= "" >        < Action name= "index" >            <result>/Namespace.jsp</result>        </action>    </package >

Struct.xml Analysis
Package role: To avoid the name of action and conflict issues;
namespace= "/front", must start with a slash, namespace preferably also use a module to name;
not writing namespace, equivalent to Namespace = "", means that as long as the action is found, it is given to
namespace treatment;
Process: First find the action under the corresponding path to match, if not, find namespace is empty action,
If the action is not found, an error will be added;
7, the return of the specific view can be determined by the user's own definition of action;
The specific method is to find the corresponding configuration item according to the returned string, to determine the contents of the view;

<constant name= "Struts.devmode" value= "true"/><package name= "front" extends= "Struts-default" namespace= "/" ><action name= "index" class= "Com.struts2.front.action.Index" ><result name= "Success" >/ Actionintroduction.jsp</result></action> </package>

the implementation of the specific action can be a common Java class, with the public String Execute method can be implemented or
Action interface;

    Package com.bjsxt.struts2.front.action;    Import com.opensymphony.xwork2.Action;    public class IndexAction1 implements Action {@Overridepublic String execute () {return "Success";}    }

    Configuration Analysis:
<class= "Com.bjsxt.struts2.front.action.Index" >
struct.xml, find the corresponding class-I instantiation object, execute the corresponding execute () method
Execution Process:
Read XML---action is class-a class object found (each access must be a new object)
When class is not configured, the default class is Actionsupport.

Actionsupport Source

   Public String Execute () throws Exception {        return SUCCESS;}

The most common is inherited from Actionsupport, the advantage is that you can directly use the Struts2 package good method

    Package com.struts2.front.action;    Import Com.opensymphony.xwork2.ActionSupport;    public class IndexAction2 extends Actionsupport {@Overridepublic String execute () {return ' success ';}    }

Cause: Actionsupport has encapsulated a number of methods that can be called directly within a subclass, which can be used directly in subclasses.

The above content is based on the horse Soldier Teacher's tutorial organized.