The basics of starting the Struts2 learning tutorial

Struts2 Overview:

Struts2 is a framework used to develop MVC applications. It provides solutions to some common problems in the development process of web application, such as verification of the legality of user input information, unified layout, internationalization, etc. Since there is Struts2, there must be Struts1. However, in essence, Struts2 is not extended from Struts1, and it should be said that it is a WebWork that has changed its brand label.

struts1 VS struts2

• Struts1 uses ActionServlet as controller, Struts2 uses filter as controller
• Each HTML form in Struts1 corresponds to an ActionForm instance, and the HTML form in Struts2 will be mapped directly to a POJO
• The verification logic of Struts1 is written in ActionForm, and the verification logic of Struts2 is written in Action
• The Action class in Struts1 must inherit the org.apache.structs.action.Action class. Any POJO in Struts2 can be an Action class.
• Struts2 uses OGNL on the page to display various object models, and you can no longer use EL and JSTL

Struts2 environment construction

Create a new Model, check Struts2, and then select the library you want to use for Struts2. You can directly select Download in the new page to download, or you can download the jar package required for Struts2 in advance and build your own (here I choose the library I built myself)

http://struts.apache.org/download.cgi#struts2516 You can select the version you want to use on this page. You can also download locally on Wulin.com: //www.VeVB.COM/softs/539810.html

After clicking the next step, name your struts2 project (when naming, it is recommended to change the name after the path of the Content Root in the second column. If you change it in the first column, just change the first column, the other two columns will not be changed)

Click Finish to complete the creation of the Struts2 project. The created project is as follows

IDEA VS Eclipse

• If we use Eclipse to create a Struts2 project, we need to copy the format of the struts2 file and the configuration of the web.xml file in the existing projects in the downloaded Struts2 package; IDEA will automatically build it for us.
• The web.xml file is struts/apps/struts2-blank1/WEB-INF/web.xml under the struts2 package.
• The struts.xml file is in struts/apps/struts2-blank/WEB-INF/classes under the struts2 package, and is created in the src directory.

Struts2 HelloWorld

After building the development environment of Struts2, we started writing the first Struts2 program. It requires that you enter the user's basic information in a form and click submit and jump to another page to display the information entered by the user. Before learning Struts2, this is very simple for us. You only need to send the page request to Servet to respond to the request to another page, and use EL and JSTL to display the information. For Struts2, this is of course a HelloWorld, and we will use this example to start explaining Struts2's various aspects of knowledge.

Write page code in index.jsp for users to enter basic information, as follows:

Write entity classes based on the form name attribute, and create getXxx and setXxx methods, Customer.java

Write code in struts.xml file to handle struts2 requests

Return to the display page show.jsp

struts.xml

 <?xml version="1.0" encoding="UTF-8"?><!DOCTYPE struts PUBLIC"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN""http://struts.apache.org/dtds/struts-2.3.dtd"><struts><package name="helloWorld" extends="struts-default"><action name="input" method="print"><result name="print">/show.jsp</result></action></package></struts>

Customer.java

 package com.struts2.hello.test;/*** Created by shkstart on 2018/03/24.*/public class Customer {private String userName;private String email;private String address;/** getXxx() setXxx() method**/public String print() {System.out.println(new Customer());return "print";}@Overridepublic String toString() {return "Customer{" +"userName='" + userName + '/'' +", email='" + email + '/'' +", address='" + address + '/'' +'}';}}

index.jsp

 <%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head><title>Input</title></head><body><table><form action="input.action" method="post"><tr><td>UserName</td><td><input type="text" name="userName"></td></tr><tr><td>Email</td><td><input type="text" name="email"></td></tr><tr><td>Address</td><td><input type="text" name="address"></td></tr><tr><td><input type="submit" value="Submit"></td></tr></form></table></body></html>

show.jsp (only displays Body tag content)

 UserName: ${userName}<br>Email: ${email}<br>Address: ${address}<br>

Detailed code explanation

Member variables in Customer.java correspond to attributes in index.jsp one by one, and do not ignore upper and lower case;

The displayed member variables in show.jsp are consistent with those in Customer.java, otherwise they cannot be displayed

The form form action value in index.jsp should be set to the name property of the action in the struts.xml file

The method attribute of the action node in the struts.xml file should be String print() method in Custome.java, and the name attribute of the result node is

Return value of String print() method

The value of the result node is the page that responds to after processing the struts2 request.

We will explain the relevant knowledge in detail later on the show.jsp page display. That’s all for our HelloWorld in Struts2. I believe that novices like me will not make any major mistakes if they follow them! !

struts.xml file node

package attribute --- struts2 Use package to organize modules

• The name attribute is required and is used to apply the current package to other packages;
• extends represents the package inherited by the current package, that is, it can inherit all configurations, usually struts-default;
• The default value of nameSpace is /. When setting this property, the set value should be added to the servletPath in the URL.

action attribute--- A struts2 request is an action

• result (Sub-label of action) The tag body represents the response result
• name corresponds to the name of the struts2 request, and does not contain the extension (the extension is defaulted to .action);
• class The full class name of the class to be sent for this struts2 request;
• method is the method of this class to be executed. The return value of the method must be String and must be consistent with the name attribute of the result node.
• The name attribute value of result is SUCCESS by default, the class default attribute is ActionSupport, and the method default value is execute

One action can have multiple result child nodes, and multiple result child nodes can be distinguished using the name attribute.

The type attribute of the result node defaults to dispatcher (forward), indicating the response type of the result

Action VS action

• In this case, Customer.java is the Action class mentioned in struts2, and the request sent by index.jsp is an action request;
• action represents a struts2 request, and the Action class represents a class that can handle the struts2 request.
• The member variables of the Action class must follow the same naming rules as the JavaBean property name. The type of the property can be of any type and must be the same as the name property of the form.
• There is at least one method to be called when struts2 executes this action request
• The same Action can also contain multiple action methods
• The Action class must have a constructor without parameters, because reflection assignment will be used.

Summarize

The above is the entire content of this article. I hope that the content of this article has certain reference value for everyone's study or work. If you have any questions, you can leave a message to communicate. Thank you for your support to Wulin.com.