In Struts2,
request parameters are directly bound to the fields in action class and this
class is placed in top of the stack when the action is executed. By implementing ModelDriven interface, you can
map the request parameters to some other model object, other than action class.
Any Action
class implementing the ModelDriven interface must supply a getModel() method
which returns the object that represents the action's model. All the request
parameters are mapped to this model object returned by getModel(). Following
example explains in detail.
Step 1: Create new maven project “struts_tutorial”. Follow
first 3 steps from the following link to make the project setup.
Step 2: Create new jsp file “register.jsp”.
register.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <form method="post" action="registration"> User Name : <input type="text" name="userName" /><br /> passowrd : <input type="password" name="password" /><br /> mailId : <input type="text" name="mailId" /><br /> <input type="submit" value="submit" /> </form> </body> </html>
Create helloWorld.jsp file with following code.
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <h1>Hello World</h1> </body> </html>
Step 3: create struts.xml. Since Struts 2 requires
struts.xml to be present in classes folder. So create struts.xml file under the
WebContent/WEB-INF/classes folder. Eclipse does not create the
"classes" folder by default, so you need to do this yourself. To do
this, right click on the WEB-INF folder in the project explorer and select New
> Folder.
struts.xml
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> <struts> <package name="default" extends="struts-default"> <action name="registration" class="learn.struts.RegisterAction"> <result name="hello">/helloWorld.jsp</result> </action> </package> </struts>
To use
ModelDriven actions, make sure that the Model Driven Interceptor is applied to
your action. This interceptor is part of the default interceptor stack
defaultStack so it is applied to all actions by default.
Step 4: Create a package “learn.struts”. Create class
RegisterAction.java inside this package.
package learn.struts; import com.opensymphony.xwork2.ModelDriven; public class RegisterAction implements ModelDriven<Employee> { /* Must initialize this instance */ private Employee employee = new Employee(); public String execute() { System.out.println("Employee Details"); System.out.println(employee.getUserName()); System.out.println(employee.getMailId()); return "hello"; } @Override public Employee getModel() { return employee; } }
Create model class Employee.java
package learn.struts; public class Employee { private String userName; private String password; private String mailId; public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getMailId() { return mailId; } public void setMailId(String mailId) { this.mailId = mailId; } @Override public String toString() { StringBuilder builder = new StringBuilder(); builder.append("Employee [userName=").append(userName) .append(", password=").append(password).append(", mailId=") .append(mailId).append("]"); return builder.toString(); } }
Run register.jsp
and check the output in console.
Final
project structure looks like following.
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