Java Implant: Struts

Configuration

We need struts2-core dependency.
Setup your basic pom.xml as follows

 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">  
  <modelVersion>4.0.0</modelVersion>  
  <groupId>com.javaimplant</groupId>  
  <artifactId>SocialNetwork</artifactId>  
  <version>0.0.1-SNAPSHOT</version>  
  <packaging>jar</packaging>  
  <name>SocialNetwork</name>  
  <url>http://maven.apache.org</url>  
  <properties>  
   <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>  
  </properties>  
  <dependencies>  
   <dependency>  
    <groupId>junit</groupId>  
    <artifactId>junit</artifactId>  
    <version>3.8.1</version>  
    <scope>test</scope>  
   </dependency>  
   <dependency>  
        <groupId>org.apache.struts</groupId>  
        <artifactId>struts2-core</artifactId>  
        <version>2.5.22</version>  
   </dependency>  
   <dependency>  
        <groupId>mysql</groupId>  
        <artifactId>mysql-connector-java</artifactId>  
        <version>8.0.19</version>  
   </dependency>  
   <dependency>  
        <groupId>org.hibernate</groupId>  
        <artifactId>hibernate-core</artifactId>  
        <version>6.0.0.Alpha4</version>  
   </dependency>  
   <dependency>  
        <groupId>org.hibernate</groupId>  
        <artifactId>hibernate-entitymanager</artifactId>  
        <version>6.0.0.Alpha4</version>  
   </dependency>  
  </dependencies>  
 </project>

To create a configurable web.xml for struts

Create a filter in web.xml
Create a filter mapping
We are offloading all of our requests that come in the tomcat(web.xml) to struts2
Struts2 passes it to the StrutsPrepareAndExecuteFilter.
This filter then executes request based on struts code written

 <?xml version="1.0" encoding="UTF-8"?>  
 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0">  
  <display-name>SocialNetwork</display-name>  
  <welcome-file-list>  
   <welcome-file>index.jsp</welcome-file>  
  </welcome-file-list> .
  <filter>  
       <filter-name>Struts2</filter-name>  
       <filter-class>org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter</filter-class>  
  </filter>  
  <filter-mapping>  
       <filter-name>Struts2</filter-name>  
       <url-pattern>/*</url-pattern>  
  </filter-mapping>  
 </web-app>

We will be using xml based configuration here since annotation based is not much supported in Struts.
For this we will create 2 xml files for Struts and Hibernate configuration as follows
Make sure you copy mapping as defined on top of both of these files .
Struts.xml

 <?xml version="1.0" encoding="UTF-8"?>  
 <!DOCTYPE struts PUBLIC  
   "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"  
   "http://struts.apache.org/dtds/struts-2.0.dtd">  
 <struts>  
 </struts>

hibernate.cfg.xml

 <?xml version="1.0" encoding="UTF-8"?>  
 <!DOCTYPE hibernate-mapping PUBLIC   
 "-//Hibernate/Hibernate Mapping DTD//EN"  
 "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

Struct Action

We configure the action in struts.xml class.

We configure the action with name property.
This property defines the name of the action that will be passed to url with an extension ".action".

Create a class and define method "execute" in it which will return a String.

The jsp to be called based on String is configured in struts.xml file based on the response from the execute method.

struts.xml

 <?xml version="1.0" encoding="UTF-8"?>  
 <!DOCTYPE struts PUBLIC  
   "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"  
   "http://struts.apache.org/dtds/struts-2.0.dtd">  
 <struts>  
           <package name="AccountSystem" extends="struts-default">  
                <action name="login" class="com.javaimplant.socialnetwork.action.LoginAction">  
                     <result name="success">/loginSuccess.jsp</result>  
                </action>  
           </package>  
 </struts>

LoginAction.java

 package com.javaimplant.socialnetwork.action;  
 public class LoginAction {  
      public String execute() {  
           System.out.println("We are executing login action!");  
           return "success";  
      }  
 }

Action Class

The action classes contain the Business Logic of the application.
The class has predefined methods and constants that can be overridden to support more enhanced functionality in Business Logic.

Functions such as validate and execute

 package com.javaimplant.socialnetwork.action;  
 import com.javaimplant.socialnetwork.model.User;  
 import com.opensymphony.xwork2.ActionSupport;  
 public class LoginAction extends ActionSupport {  
      private static final long serialVersionUID = 1L;  
      private User user;  
      @Override  
      public void validate() {  
      }  
      @Override  
      public String execute() {  
           System.out.println("We are executing login action!");  
           System.out.println(user.getUserName());  
           System.out.println(user.getPassword());  
           return SUCCESS;  
      }  
      public User getUser() {  
           return user;  
      }  
      public void setUser(User user) {  
           this.user = user;  
      }  
 }

Views

Struts has its own tag library
To include and use tag library in struts see snippet below

See Taglib tag to include library
See <S:form> tag to create struts form.

 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"  
   pageEncoding="ISO-8859-1"%>  
 <!DOCTYPE html>  
 <%@ taglib prefix="s" uri="/struts-tags" %>  
 <html>  
 <head>  
 <meta charset="ISO-8859-1">  
 <title>Welcome to our Social Network</title>  
 </head>  
 <body>  
 Welcome to our Social Network  
 <s:form action="login">  
      <s:textfield key="user.userName" label="User Name"></s:textfield>  
      <s:password key="user.password" label="Password"></s:password>  
      <s:submit/>  
 </s:form>  
 </body>  
 </html>

Validation in Struts

To add validation in Struts we use the method addFieldError() as shown in snippet

 package com.javaimplant.socialnetwork.action;  
 import java.util.List;  
 import org.apache.commons.lang3.StringUtils;  
 import com.javaimplant.socialnetwork.dao.UserDAO;  
 import com.javaimplant.socialnetwork.model.User;  
 import com.opensymphony.xwork2.ActionSupport;  
 public class LoginAction extends ActionSupport {  
      private static final long serialVersionUID = 1L;  
      private User user;  
      @Override  
      public void validate() {  
           UserDAO dao=new UserDAO();  
           if(StringUtils.isEmpty(user.getUserName()))  
           {  
                addFieldError("user.userName","User Name cannot be blank");  
                return;  
           }  
           List<User> users=dao.getUserByName(user.getUserName());  
           if(users.isEmpty())  
           {  
                addFieldError("user.userName","User Not Found");  
                return;  
           }  
           if(!users.get(0).getPassword().equals(user.getPassword()))  
           {  
                addFieldError("user.password","Password mismatch");  
                return;                 
           }  
           this.user=users.get(0);  
      }  
      @Override  
      public String execute() {  
           System.out.println("We are executing login action!");  
           System.out.println(user.getUserName());  
           System.out.println(user.getPassword());  
           return SUCCESS;  
      }  
      public String insertUser()  
      {  
           UserDAO dao=new UserDAO();  
           dao.insertUser(user);  
           return SUCCESS;  
      }  
      public String addUser()  
      {  
           return SUCCESS;  
      }  
      public User getUser() {  
           return user;  
      }  
      public void setUser(User user) {  
           this.user = user;  
      }  
 }

This adds validation to our field in view.

Each validation when triggered gives a result of type input for the action in concern which needs to be handled in struts.xml as follows

 <?xml version="1.0" encoding="UTF-8"?>  
 <!DOCTYPE struts PUBLIC  
   "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"  
   "http://struts.apache.org/dtds/struts-2.0.dtd">  
 <struts>  
           <package name="AccountSystem" extends="struts-default">  
                <action name="login" class="com.javaimplant.socialnetwork.action.LoginAction">  
                     <result name="success">/loginSuccess.jsp</result>  
                     <result name="input">/index.jsp</result>  
                </action>  
           </package>  
 </struts>

Session in Struts

Define as attribute in class of type Map

      private Map<String,Object> userSession;  
      public Map<String, Object> getUserSession() {  
           return userSession;  
      }  
      public void setUserSession(Map<String, Object> userSession) {  
           this.userSession = userSession;  
      }

Generate getter and setter of this session object.
Add into session object MAP as follows

```
 userSession.put("user",this.user);  
```

The action must implement the following SessionAware interface

The interface has a method setSession which is used to set the session MAP variable into as the session.

 public class LoginAction extends ActionSupport implements SessionAware {  
      private User user;  
      private Map<String,Object> userSession;  
      public Map<String, Object> getUserSession() {  
           return userSession;  
      }  
      public void setUserSession(Map<String, Object> userSession) {  
           this.userSession = userSession;  
      }  
      @Override  
      public void validate() {  
           UserDAO dao=new UserDAO();  
           if(StringUtils.isEmpty(user.getUserName()))  
           {  
                addFieldError("user.userName","User Name cannot be blank");  
                return;  
           }  
           List<User> users=dao.getUserByName(user.getUserName());  
           if(users.isEmpty())  
           {  
                addFieldError("user.userName","User Not Found");  
                return;  
           }  
           if(!users.get(0).getPassword().equals(user.getPassword()))  
           {  
                addFieldError("user.password","Password mismatch");  
                return;                 
           }  
           this.user=users.get(0);  
           userSession.put("currentUser",this.user);  
           dao.close();  
      }  
      @Override  
      public String execute() {  
           System.out.println("We are executing login action!");  
           System.out.println(user.getUserName());  
           System.out.println(user.getPassword());  
           return SUCCESS;  
      }  
      @Override  
      public void setSession(Map<String, Object> session) {  
           this.userSession=session;  
      }  
 }

Java Implant

Struts

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