Hatti matim tim, Ami mathe pari Dim: July 2007

(If u don't how struts2+spring works, see struts2+spring workflow)

What i'm trying do to here:
i have a table named "User" in our database.
now i want to build a web-application using struts2+spring+hibernate
1. to add new user to database and
2. to log in to home page for existing user.

Download sourcecodes

Files (java/xml) i'll create for this:

1. "User" table in database.

2. User.java:
which will be mapped with that "User" table.
3. User.hbm.xml:
that maps User table with User.java.
4. IUserDao.java:
interface for data access object.
5. UserDAOHibernateImpl.java:
which implements IUserDao.java
6. IUserService.java:
interface for service
7. UserServiceImpl.java:
which implements IUserService
8. UserAction.java:
action class for struts2
9. applicationContext.xml:
Register your objects via the Spring configuration.
all the above files and data source will be configured here.
10. struts.xml:
its the configuration file for struts2 (which was struts-config.xml for struts1)
11. output *.jsp files, i've used 3 here:
11.i) addUser.jsp: to add new user in DB
11.ii) login.jsp: to log in existing user
11.iii) hello.jsp: says hello to the user after successful log in.
12. xml files for validation
13. and good old web.xml

jar files we need are same as this example

so now.......Ready... Set... GO!

1.Let, database used is mysql. database name ExampleDB and table name User.


create database ExampleDB;
use ExampleDB;
create table User(
name varchar(20),
id varchar(20) not null primary key
);

2. write the web.xml file:

In the web.xml file, Struts defines its FilterDispatcher, the Servlet Filter class that initializes the Struts framework and handles all requests.

If you don't know how to write web.xml for struts2, see web.xml

In most cases, we can simply use web.xml for struts2-blank template. we just need to add the following lines to configure the Spring listener.

<listener>
<listener-class>
org.springframework.web.context.ContextLoaderListener

</listener-class>
</listener>

Everything else is same as any other web.xml for struts2.

<?xml version="1.0" encoding="UTF-8"?>

<web-app id="example" version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<filter>
<filter-name>struts2</filter-name>
<filter-class>
org.apache.struts2.dispatcher.FilterDispatcher
</filter-class>
</filter>

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

</filter-mapping>

<welcome-file-list>
<welcome-file>/login.jsp</welcome-file>
</welcome-file-list>

<listener>
<listener-class>
org.springframework.web.context.ContextLoaderListener

</listener-class>
</listener>

</web-app>

3.write User.java file that will be used to map the User table.

package com.example.user; 

public class User {

private String id;
private String name;
public String getName() {
return name;
}
public void setName(String name) {

this.name = name;
}
/**  * @return Returns the userId.  */

public String getId() {
return id;
}

/**  * @param userId The userId to set.  */
public void setId(String userId) {
this.id = userId;
}

}

4.Now maps the database table with .java file. To do this, write the mapping file, User.hbm.xml :

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >

<!--Maps User.java class with User
database table  -->

<hibernate-mapping>
<class name="com.example.user.User" 

   table="User">

<id name="id" column="id" >
<generator class="assigned" />

</id>
<!--
 id tag represents the primary key of
  database table  generator class defines
  how key will be generated.
  Here we've choose "assigned", that is key will be
  assigned before insert.
  Other generator classes are:
  1.native
  2.increment : auto increment the key value
-->

<property name="name" column="name" />

<!--
property tag maps columns other than
the primary key column.
-->

</class>
</hibernate-mapping>

Put all your *.hbm.xml files in com/example/user/hbm folder.

5.Write the Data Access Object that would be used to access database using hibernate.
At first we would write the interface : IUserDao.java

package com.example.user ; 
public interface IUserDao {
public String addUser(User user);
public User findUserById(final String Id);


}

//Now write UserDAOHibernateImpl.java : 

package com.example.user; 
import org.springframework.orm.
   hibernate3.HibernateTemplate;

public class UserDAOHibernateImpl
 implements IUserDao
extends HibernateDaoSupport 
{


public String addUser(User user){
  String success;
  try{
     getHibernateTemplate().save(user);
     success="Welcome !";
   }
  catch(Exception e){
       success="Sorry, user cannot be added";
   }
  return success;
}

public User findUserById(final String id){

  return (User)

        getHibernateTemplate().get(User.class, id);
}

}

getHibernateTemplate().save(user) would insert user into the User database table
we've used HibernateTemplate because it provides easy method to do basic queries and also it is thread safe.
get method will return the user object with given id if such an user existed, otherwise null will be returned.

6. Write the service class (it would seem a little redundant at first, but it's the best practice to provide service layer between action and dao class).
Usually database transaction management is applied on this layer.

//Interface for service class:

package com.example.user; 

public interface IUserService {
public String add(User user);
public User findById(final String Id);

}

//Service class: UserServiceImpl.java

package com.example.user; 
public class UserServiceImpl implements IUserService{

private IUserDao userDao;

public IUserDao getUserDao() {
 return userDao;
}
public void setUserDao(IUserDao userDao) {

//userDao will be set by applicationContext.xml 

this.userDao = userDao;
}

public String add(User user){
     String result=userDao.addUser(user);
     return result;
}
public User findById(String Id){
    User user=userDao.findUserById(Id);
    return user;
}

}

7.At last, now write the action class: UserAction.java
Here our action class will
1.take the user id
2.retrieve user name from database
3.and say " Hello <user name>"
4.add new user

package com.example.user; 

import java.util.Map; 
import com.opensymphony.xwork2.Action; 
import com.opensymphony.xwork2.ActionContext ; 


public class UserAction {
private IUserService userService;
private User user;
private String id;
private String name;

/**  * Constructor * @param userService  */
public UserAction(IUserService userService)
{

this.userService=userService;

// will be set by applicationContext.xml  
}
public String execute() {
this.user=

   (User)userService.findById(this.id);
String result;
if(user==null){

// returns error if user doesn't exist.  

   result="User id does not exist";
   ActionContext.getContext().
                 getSession().

                 put("result", result);
   return Action.ERROR;
}
else   {
     result="";
     ActionContext.getContext().
                   getSession().
                   put("user", user);

    // puts user object in session  
      return Action.SUCCESS;
  }
}
public String signup(){
   return Action.SUCCESS;
}
public String addUser(){
    String result;
    this.user=

       (User)userService.findById(id);
    if(user==null){
       user=new User();
       user.setId(this.id);
       user.setName(this.name);
       result=userService.add (user);
       ActionContext.getContext().
                     getSession().
                     put("user", user);
 }
 else{
    result="Id already used,
           Choose another Id";
    ActionContext.getContext().
                    getSession().
                    put("result",result);

      return Action.ERROR;
    }
   ActionContext.getContext().
                 getSession().
                 put("result", result);
   return Action.SUCCESS;
 }
public String getId() {
     return id;
 }
public void setId(String id) {
    this.id = id;
 }

public String getName() {
     return name;
 }
public void setName(String name) {
    this.name = name;
 }


}

8.Write the jsp files: we will use 3 jsps here
1.login.jsp: take the id from user
2.hello.jsp: say hello
3.addUser.jsp: add a user


login.jsp:
<%@ taglib prefix="s" uri="/struts-tags"%>

<html >
<head>
<title>Log in</title>
</head>
<body>
<h2><s:property value="#session.result"/></h2>
<s:form action="SignIn" validate="true">
<s:textfield label="User Id" name="id" required="true"/>
<s:submit value="Login" />
</s:form>
<a href=" <s:url action="SignUp"/> "> Sign Up As A New User </a>
</body>

</html>
---------------------------------------------------------------
hello.jsp
<%@ taglib prefix="s" uri="/struts-tags"%>
<html >
<head>
<title>Hello</title>
</head>
<body>
<s:if test="#session.user!=null">
 <h2>Hello <s:property value="#session.user.name"/></h2>
</s:if>
</body>

</html>
--------------------------------------------------------------------
addUser.jsp
<%@ taglib prefix="s" uri="/struts-tags"%>
<html >
<head>
<title>Sign Up</title>
</head>
<body>
<s:property value="#session.result"/></h2>
<s:form action="add" validate="true">
     <s:textfield label="User Name " name="name" required="true"/>
     <s:textfield label="User Id" name="id" required="true"/>
     <s:submit value="Submit"/>
</s:form>
</body>

</html>

9. Write the applicationContext.xml file:

<?xml version=" 1.0" encoding="UTF-8"?>

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
"http://www.springframework.org/dtd/spring-beans.dtd">

<!--
- Application context definition
--><beans>
<!-- ========================= RESOURCE DEFINITIONS ========================= -->

<!-- Creating a data source connection pool-->

<bean id="dataSource"
 class="org.springframework.jdbc.datasource.DriverManagerDataSource ">

<property name="driverClassName">

 <value>com.mysql.jdbc.Driver</value>
</property>
<property name="url">
 <value>jdbc:mysql://localhost:3306/ExampleDB</value>

</property>
<!-- Provide username and password for mysql -->
<property name="username" value="root"/>
<property name="password" value=""/>



</bean>


<!-- Hibernate SessionFactory -->

<bean id="sessionFactory"
 class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">

<property name="dataSource"><ref bean="dataSource"/></property>
<property name="mappingDirectoryLocations">
<list>

<value>classpath:/com/example/user/hbm</value>
</list>
</property>

<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">

org.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.show_sql">true</prop>
<!-- show the sql command in console -->
</props>
</property>

</bean>



<!-- ========================= BUSINESS OBJECT DEFINITIONS ========================= -->

<!--
Data access object: Hibernate implementation.
-->

<!-- with transaction -->
<bean id="hibernateTemplate"

      class="org.springframework.orm.hibernate3.HibernateTemplate">
<property name="sessionFactory">
 <ref bean="sessionFactory"/>

</property>
</bean>

<bean id="UserDaoImpl" class="com.example.user.UserDAOHibernateImpl">
<property name="hibernateTemplate">

<ref bean="hibernateTemplate"/>
</property>
<!-- set HibernateTemplate in UserDAOHibernateImpl.java class-->
</bean>

<!--
Defination of service targets
-->
<bean id="UserServiceTarget" 

    class="com.example.user.UserServiceImpl">
<property name="userDao">
<ref bean="UserDaoImpl"/>

</property>
<!-- set IUserDao in UserServiceImpl.java class-->
</bean>


<!--
Definition of Transaction Manager
-->
<bean id="transactionManager"
 class="org.springframework.orm.hibernate3.HibernateTransactionManager">

<property name="sessionFactory">
<ref bean="sessionFactory"/>
</property>
</bean>
<!--
Base service object
-->

<bean id="Service"
  class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean"
 abstract="true">
<property name="transactionManager">

<ref bean="transactionManager"/>
</property>

<property name="transactionAttributes">
<props>


   <prop key="add">PROPAGATION_REQUIRED</prop>
   <prop key="find*">PROPAGATION_REQUIRED,readOnly</prop>
<!-- specifies the methods on which transaction management will be applied-->

</props>
</property>
</bean>

<!--
Children service objects using base service and service
targets
-->

<bean id="UserService" parent="Service">

<property name="target">
<ref bean="UserServiceTarget"/>
</property>

</bean>


<!--
Definition of Action objects
-->

<bean id="userAction"
        class=" com.example.user.UserAction" singleton="false">
 <constructor-arg>

  <ref bean="UserService"/>
  </constructor-arg>
 <!-- set IUserService in UserAction.java's constructor-->
</bean>

</beans>

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10. Last step :) now, write the struts.xml file:

<?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="user" extends="struts-default">


<action name="SignIn" method="execute" class="userAction" >
<result>/hello.jsp</result>

  <result name="error">/login.jsp</result>
</action>
<action name="SignUp" method="signup" class="userAction">

   <result>/addUser.jsp</result>
</action>

<action name="add" method="addUser" class="userAction">

    <result>/hello.jsp</result>
   <result name="error">/addUser.jsp</result> 
</action>

</package>

</struts>

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------------------------------------------------------------------------------------------------
And here's the validation file, just save it under the same folder as the action.
filename should be <action-classname>-<action-name>-validation.xml
For login action, validation filename would be UserAction-SignIn-validation.xml

<!DOCTYPE validators PUBLIC "-//OpenSymphony Group//XWork Validator 1.0.2//EN"
 "http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">

<!--
Validation rules for sign in action
-->
<validators>
<field name="id">
<field-validator type="requiredstring">
   <message>You must enter user id</message>

</field-validator>
</field>
</validators>

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--
Sheetal

Hatti matim tim, Ami mathe pari Dim

Thursday, July 12, 2007

Make a difference

Monday, July 02, 2007

Migrating from struts1 to struts2

struts2+spring+hibernate(part2)

struts2 + spring + hibernate