Struts 2 – Database Access

Struts 2 – Database Access

Struts is a MVC framework and not a database framework but it provides excellent support for JPA/Hibernate integration. We shall look at the hibernate integration in a later chapter, but in this chapter we shall use plain old JDBC to access the database.

The first step in this chapter is to setup and prime our database. I am using MySQL as my database for this example. I have MySQL installed on my machine and I have created a new database called “struts_tutorial”. I have created a table called login and populated it with some values. Below is the script I used to create and populate the table.

My MYSQL database has the default username “root” and “root123” password

CREATE TABLE `struts_tutorial`.`login`(
`user` VARCHAR(10) NOT NULL ,
`password` VARCHAR(10) NOT NULL ,
`name` VARCHAR(20) NOT NULL ,
   PRIMARY KEY (`user`)
) ENGINE =InnoDB;

INSERT INTO `struts_tutorial`.`login`(`user`,`password`,`name`)
VALUES ('scott','navy','Scott Burgemott');

Next step is to download the MySQL Connector jar file and placing this file in the WEB-INF\lib folder of your project. After we have done this, we are now ready to create the action class.

Create Action

The action class has the properties corresponding to the columns in the database table. We have user, password and name as String attributes. In the action method, we use the user and password parameters to check if the user exists, if so, we display the user name in the next screen.

If the user has entered wrong information, we send them to the login screen again.

Following is the content of LoginAction.java file −

package com.ducatindia.struts2;

importjava.sql.Connection;
importjava.sql.DriverManager;
importjava.sql.PreparedStatement;
importjava.sql.ResultSet;

import com.opensymphony.xwork2.ActionSupport;

publicclassLoginActionextendsActionSupport{

privateString user;
privateString password;
privateString name;

publicString execute(){
String ret = ERROR;
Connection conn =null;

try{
String URL ="jdbc:mysql://localhost/struts_tutorial";
Class.forName("com.mysql.jdbc.Driver");
conn=DriverManager.getConnection(URL,"root","root123");
Stringsql="SELECT name FROM login WHERE";
sql+=" user = ? AND password = ?";
PreparedStatementps=conn.prepareStatement(sql);
ps.setString(1, user);
ps.setString(2, password);
ResultSetrs=ps.executeQuery();

while(rs.next()){
name=rs.getString(1);
ret= SUCCESS;
}
}catch(Exception e){
ret= ERROR;
}finally{
if(conn !=null){
try{
conn.close();
}catch(Exception e){
}
}
}
return ret;
}

publicStringgetUser(){
return user;
}

publicvoidsetUser(String user){
this.user= user;
}

publicStringgetPassword(){
return password;
}

publicvoidsetPassword(String password){
this.password= password;
}

publicStringgetName(){
return name;
}

publicvoidsetName(String name){
this.name = name;
}
}

Create Main Page

Now, let us create a JSP file index.jsp to collect the username and password. This username and password will be checked against the database.

<%@ page language ="java"contentType="text/html; charset = ISO-8859-1"pageEncoding="ISO-8859-1"%>

<%@taglib prefix ="s"uri="/struts-tags"%>

< !DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
   "http://www.w3.org/TR/html4/loose.dtd">

< html>
< head>
< title>Login< /title>
< /head>

< body>
< formaction="loginaction"method="post">
User:< br/>< inputtype="text"name="user"/>< br/>
Password:< br/>< inputtype="password"name="password"/>< br/>
< inputtype="submit"value="Login"/>		
< /form>
< /body>
< /html>

Create Views

Now let us create success.jsp file which will be invoked in case action returns SUCCESS, but we will have another view file in case of an ERROR is returned from the action.

<%@ page contentType="text/html; charset = UTF-8" %>

<%@taglib prefix ="s"uri="/struts-tags" %>

< html>
< head>
< title>Successful Login< /title>
< /head>

< body>
      Hello World, < s:propertyvalue="name"/>
< /body>
< /html>

Following will be the view file error.jsp in case of an ERROR is returned from the action.

<%@ page contentType="text/html; charset = UTF-8" %>

<%@taglib prefix ="s"uri="/struts-tags" %>

< html>
< head>
< title>Invalid User Name or Password< /title>
< /head>

< body>
      Wrong user name or password provided.
< /body>
< /html>

Configuration Files

Finally, let us put everything together using the struts.xml configuration file 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>
< constantname="struts.devMode"value="true"/>
< packagename="helloworld"extends="struts-default">

< actionname="loginaction"
class="com.ducatindia.struts2.LoginAction"
method="execute">
< resultname="success">/success.jsp< /result>
< resultname="error">/error.jsp< /result>
< /action>

< /package>
< /struts>

Following is the content of web.xml file −

< ?xml version ="1.0"Encoding="UTF-8"?>
< web-appxmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
   http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
id="WebApp_ID"version="3.0">

< display-name>Struts 2< /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.FilterDispatcher
< /filter-class>
< /filter>

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

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