Struts2: Core configuration file

Package labels

• 1:Similar to code package, differentactionAnd you want to configureaction, must be written firstpackageThe label,packageIn order to configureaction.
• 2: packageTag attributes.
  • (1) nameProperties:
    • nameAttribute values have nothing to do with the function itself,
    • You can write more than one configuration filepackageThe label,nameAttribute values cannot be the same.
  • (2) extendsProperties:
    • Property values are fixedextends="struts-default".
    • I wrote this property inpackageThe class inside hasactionFunction.
  • (3) namespaceProperties:
    • namespaceAttribute values andactionInside the labelnameAttribute values constitute an inter-visit path.

The action tags.

• 1: actionThe tagactionVisit path between
• 2: actionTag attributes
  • (1) nameProperties:
    • namespaceAttribute values andactionInside the labelnameAttribute values constitute an inter-visit path.
    • inpackageWrite multiple tags insideactionTag, butactionthenameAttribute values cannot be the same
  • (2) classProperties:
    • actionThe full path
  • (3) methodProperties:
    • For example, inactionThe method executed by default insideexecuteMethod, but inactionThere are other methods in there.
    • letactionInside more than one method is executed, usingmethodConfigure.

The result tag.

• 1:According to theactionMethod return value, configured to a different path inside.
• 2: resultTag attributes.
  • (1) nameProperties:
    • Same as the method return value.
  • (2)The type attribute:
    • Configure how to go to the path (forward or redirect).
    • typeAttribute default value to perform the forwarding operation.

Source:

• src:struts.xml

	<package name="hellodemo" extends="struts-default" namespace="/">
		<! -- name: access name -->
		<action name="hello" class="com.yap.action.HelloAction">
			<! -- Configure method return value to page -->
			<result name="ok">/hello.jsp</result>
		</action>
	</package>

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Change the default Struts2 constant value

• 1:Commonly used way
  • instruts.xmlTo configure.
    • <constant name="struts.i18n.encoding" value="UTF-8"/>
• 2:There are two other ways.
  • insrcThe following to createstruts.propertiesmodified
  • inweb.xmlConfigure.

Describes the most commonly used constants

• struts.i18n.encoding = UTF-8
• 1:The form submits data toactionInside, inactionYou can get form submission data,
• 2:Form submission data in Chinese, there are garbled problems, solve:
  • postCommit directly to set the encoding
  • getCommit for encoding conversion
• 3:If theactionGet the form passpostMethods to submit Chinese, Chinese garbled between the problem to help solve, do not need to deal with their own problems.

Modular development

• 1:Write the configuration file separately and add the configuration file to the core configuration file
  • <include file=" path "/>: Introduces XML paths.

How actions are written

• 1: actionThere are three ways to write
  • Create a normal class that inherits no classes and implements no interfaces
  • Create classes to implement interfacesAction
  • Create class, inherit classActionSupporte

Methods to access action (emphasis)

• 1:There are three ways to do this
  • (1) Use the method property of the action tag to write the method of the action to execute.
  • (2) Use the wildcard method.
  • (3) Dynamic inter-visit implementation (no).
• 2:Presentation error
  • (1)This error occurs if the Action method returns a value but is not configured in the configuration file.
    • No result defined for action cn.itcast.action.HelloAction and result ok
  • (2) The method in the action must return a value. If it does return a value, the type must be String
  • (3)Action methods can have no return value. If there is no return value, the result tag does not need to be configured
    • Write the method return value as void.
    • Let’s return the value, return NONE.

<! -- Use the action tag method attribute --> <! Create action, create multiple methods, the drawback is that each action method needs to be created. -->public class BookAction extends ActionSupport {
	/ / add
	public String add(a) {
		System.out.println("add...........");
		return NONE;
	}

	/ / modify
	public String update(a) {
		System.out.println("update.........");
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• xml:struts.xml

	<! Configure action method access -->
	<package name="methoddemo" extends="struts-default" namespace="/">
	
	 <! Write the name of the method in the action to be executed -->
		<action name="addAction" class="com.yap.method.BookAction" method="add"></action>
		<! Update method -->
		<action name="updateAction" class="com.yap.method.BookAction" method="update"></action>
	</package>

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• psm:http://localhost/Struts2_demo/updateAction.action
• psm:http://localhost/Struts2_demo/addAction.action

Use wildcards

• 1: 在actionThe label insidenameProperties,nameWrite symbols inside property values*The asterisk
• xml:struts.xml

	<! -- Wildcard implementation -->
<package name="methoddemo" extends="struts-default" namespace="/"> 
	<! Add (2) update (action) update (book_update); Use book_* to match the method property, which is equivalent to update the above two paths.
	<action name="book_*" class="com.yap.method.BookAction" method="{1}"></action>
</package>
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• psm:http://localhost/Struts2_demo/book_update.action
• psm:http://localhost/Struts2_demo/book_add.action