GunnaSatria

Simple JSP Part 4

gunnasatria — Tue, 07 Oct 2008 08:20:47 +0000

As i promised a long.. long time ago..
i will write an example of using java beans in jsp pages.
The idea of this scenario is so you as a java web developer not being mixed up between HTML scripts and Java scripts.
So, if in the previous example we embedded some java instructions in HTML scripts then for this tutorial we will separate both.

Supposed you have this usual Java class acting as our first created java beans.
package pages;

public class HelloWorld {

public String getMessage(){
return “Hello Word”;
}

}

and then you have a regular HTML in a JSP file like below,

Simple JSP Part 4

and let’s name it message.jsp

Now, the idea is to display message from our HelloWorld class to our jsp page. How we will do it?
Add below java instruction between body tag in our message.jsp

pages.HelloWord hw = new pages.HelloWorld();
out.println(“message is: “+hw.getMessage());

To putting it all together, below is the full code.

Simple JSP Part 4

pages.HelloWord hw = new pages.HelloWorld();
out.println(“message is: “+hw.getMessage());

Then you will see a nice hello word message.
This is just a tiny example of how usefull java beans will be. The other benefit is if separate our logic into our java class, then we will able to test it first and will not having much difficulties in debuging compared to when we join our java instructions in our jsp pages.
But.. there is always a backside of this. If you want to update your java class, then you have to restart your web server to get it work.

So… have a nice try n error.

Simple JSP part 3

gunnasatria — Mon, 07 Jan 2008 02:12:53 +0000

Now we are trying to connect our web application to a database. I use Northwind database here as an example database.
For you who don’t know what Northwind is, it is a sample database given if you install MS Access. I am sorry for non Windows user, but if you follow below tutorial you should also do it in another database like MySQL or PostgreSQL.
Open your previous SimpleJSP project, create a new file under simplejsp folder and named it employees.jsp.
What we are trying to do is to display all data from Employees table in Northwind database in our new employees.jsp page.

Copy and paste below code,

<%@ page import=”java.sql.*”%>
<%@ page import=”java.util.*”%>
<%
List empList = new ArrayList();

Class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”);
Connection conn = DriverManager.getConnection(“jdbc:odbc:northwind”,”",”");
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(“select EmployeeId,LastName,FirstName,Title from Employees”);
while(rs.next()){
Map emp = new HashMap();
emp.put(“id”,rs.getInt(1));
emp.put(“firstname”,rs.getString(2));
emp.put(“lastname”,rs.getString(3));
emp.put(“title”,rs.getString(4));
empList.add(emp);
}
rs.close();
stmt.close();
conn.close();
%>

Employees

Employees

<%
for(int i=0;i Map emp = (Map)empList.get(i);
%>

<%
}
%>

<%=emp.get(“id”)%>

<%=emp.get(“lastname”)%>

<%=emp.get(“firstname”)%>

<%=emp.get(“title”)%>

Before you try our new page, make sure to check your odbc whether it’s already had northwind DSN. Check it in ODBC Administrator.

If you doesn’t have it yet, create a new DSN, name it northwind and select Northwind.mdb file. If DSN already configured then start your jetty and go to http://localhost:8080/employees.jsp

You should get something like this,

Employees

1	Nancy	Davolio	Sales Representative
2	Andrew	Fuller	Vice President, Sales
3	Janet	Leverling	Sales Representative
4	Margaret	Peacock	Sales Representative
5	Steven	Buchanan	Sales Manager
6	Michael	Suyama	Sales Representative
7	Robert	King	Sales Representative
8	Laura	Callahan	Inside Sales Coordinator
9	Anne	Dodsworth	Sales Representative

Let’s break down our code to figure out what is all about..

1. Import package
<%@ page import=”java.sql.*”%>
<%@ page import=”java.util.*”%>
Above code means that we are importing all Classes that are under java.sql and java.util.
java.sql package contains classes that are used to connect to database while java.util package contains class that are usefull as data holder like List and Vector.

2. Create Connection
Class.forName(“sun.jdbc.odbc.JdbcOdbcDriver”);
Because we are using MS Access, so we are using sun.jdbc.odbc.JdbcOdbcDriver class as java driver for ODBC database.
If you are using other type of database, you must change it to appropriate driver class.

Connection conn = DriverManager.getConnection(“jdbc:odbc:northwind”,”",”");
First parameter in DriverManager.getConnection is our database URL, the second one is user that is allowed to access the database, and the third is the password.

3. Fetch Data
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(“select EmployeeId,LastName,FirstName,Title from Employees”);
while(rs.next()){
Map emp = new HashMap();
emp.put(“id”,rs.getInt(1));
emp.put(“firstname”,rs.getString(2));
emp.put(“lastname”,rs.getString(3));
emp.put(“title”,rs.getString(4));
empList.add(emp);
}
To execute the SQL query, we must create Statement object first. From Statement object we can create ResultSet object that will hold our query result. As you can see that ResultSet rs hold “select EmployeeId,LastName,FirstName,Title from Employees” SQL query result. The rest of the code is just to set result data in a map for s single row and List for the whole data.

4. Close connection
rs.close();
stmt.close();
conn.close();
Don’t forget to always close all of your connection object after you done with your database operation.

5. Display fetched Data

Employees

Employees

<%
for(int i=0;i Map emp = (Map)empList.get(i);
%>

<%
}
%>
<%=emp.get(“id”)%> <%=emp.get(“lastname”)%> <%=emp.get(“firstname”)%> <%=emp.get(“title”)%>

Here we just use a simple table component from HTML to display our fetched data.

That’s all for now. Next tutorial will be JSP + Beans.
Thanks

Simple JSP part 2

gunnasatria — Sat, 05 Jan 2008 09:09:19 +0000

Our next tutorial is about handling user input. We will start with the most common input component which is text field.
Open your index.jsp and add new codes like below,
<%
out.println(“hello world”);
%>

SimpleJSP

Run your jetty and open index.jsp. You will see something like below, one text field with maximum input of 20 character with one Login button.

Right now, if you type anything and press the button it will do nothing. Let’s change our code a little..

<%
String usernameInput = request.getParameter(“username”);
if(null!=usernameInput){
out.println(“hello “+usernameInput);
}else{
out.println(“hello world”);
}
%>

SimpleJSP

Refresh your index.jsp and try type any text in your text field and press Login.. do you see some changing??
What you type will show in the hello text.

You notice that in the latest code, there is one line that capture value from username text field which is request.getParameter(“username”). So, just use this syntax to capture any html input component by changing the parameter input in request.getParameter.
This is the code if we want to have some login page.
<%
String usernameInput = request.getParameter(“username”);
String passwordInput = request.getParameter(“password”);
if(null!=usernameInput && null!=passwordInput ){
out.println(“process user with username=”+usernameInput+” and password = “+passwordInput);
}else{
out.println(“hello world”);
}
%>

SimpleJSP

The next tutorial will be connection to database.
Thanks

Simple JSP part 1

gunnasatria — Fri, 04 Jan 2008 13:32:01 +0000

This post is dedicated for you who want to start learning how to create a web application using Java using only simple JSP. I assumed here you already have Java basic knowledge. Please enjoy.
First thing in creating a web application is an editor. I recommend you use Eclipse. This is a powerful and free editor with a lot of plug-ins support. And you may want to add Jetty Launcher plug in to help you continue with this tutorial.
Second, you need JDK(Java Development Kit) use 1.4 version or 1.5, but in here i will use 1.5
Last, you need a servlet container. This is a program that our web application will run in it. You can choose Tomcat or Jetty. I use Jetty,a light weight container.
If you already have all requirements then we will start coding.

Create a new Java project in Eclipse, call it SimpleJSP and set your output folder to simplejsp/WEB-INF/classes.

Create a new file in WEB-INF folder and named it web.xml. Paste this below code,

version = “1.0″ encoding = “utf-8″?>

Simple JSP Application

30

html
text/html

txt
text/plain

index.jsp
index.html

After that create new file index.jsp in simplejsp folder and type below code,

<%
out.println(“hello world”);
%>

One thing you must remember is, all code in your page that is between <% and %> will be take it as a Java code, so if you want to write a HTML tag inside <%%> then you must use out.println syntax. But if it’s outside the <%%> then you can just type the HTML tag like the usual HTML page.

Below image is what your project will look like,

Now we will try to run our web application. Choose Run menu and click Open Run Dialog, configure Project, Jetty Home, web root dir. You can see in picture below as an example.

Click run, open your browser and type http://localhost:8080/index.jsp
I predict this will be your output,

Don’t worry.. i know this will happen. It is because we need to link tools.jar file from jdk so eclipse can compile our jsp file.
Right click in your project and choose Build Path->Add External Archieve then select your tools.jar file, it is located in your [jdk home]\lib folder

After that restart your Jetty, and refresh the index.jsp page.. voilla..Congratulations you already create your first jsp page.

In the next post, we will continue with handling user input.
Thanks.

Create Virtual Host Name using Apache

gunnasatria — Thu, 13 Dec 2007 13:07:25 +0000

Suppose you have a web application running on Apache and you want to change the url address of your application to be more friendly like http://www.gunnasatria.com
All you have to do is to create a virtual host name.

Edit your httpd.conf file, usually it’s located in conf folder and add the lines

NameVirtualHost [your server ip]:[active port]

ServerName http://www.gunnasatria.com
DocumentRoot [folder point to your web app]

Then restart your apache service.
But this is not the only step, you must add the new url to your DNS to point to your server IP. So every request for the new url points to your server IP.

Good Luck

Hibernate Annotation Tutorial

gunnasatria — Mon, 19 Nov 2007 13:33:18 +0000

As in my previous post, right now i’m working on a project that use Hibernate annotation. I feel great and really believe that i am making a right choice. So, i want to share my experience using it here.

Suppose you have one simple Table called Unit.
Unit has 4 field ID,NAME,CREATE_BY and LOCATION.
First, is create a hibernate configuration file hibernate.cfg.xml

“-//Hibernate/Hibernate Configuration DTD 3.0//EN”
“http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd”>

[driver]
[url]
[username]
[password]

1

org.hibernate.dialect.OracleDialect

thread

org.hibernate.cache.NoCacheProvider

true

none

Next,you create pojo class to map the table.
*updated 24-June-2011 thanks to Giri

@Entity
@Table(name=”UNITS_PER_ASSET”)

public class Unit {
private Integer id;
private String name;
private String createBy;
private String location;

public Unit(){}

@Column(name=”CREATE_BY”)
public String getCreateBy() {
return createBy;
}

public void setCreateBy(String createBy) {
this.createBy = createBy;
}

@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator = “SEQ_UNIT”)
@SequenceGenerator(name=”SEQ_UNIT”, sequenceName = “SEQ_UNIT”)
@Column(name=”ID”)
public Integer getId() {
return id;
}

public void setId(Integer id) {
this.id = id;
}

@Column(name=”LOCATION_ID”)
public String getLocation() {
return location;
}

public void setLocation(String location) {
this.location = location;
}

@Column(name=”NAME”)
public String getName() {
return name;
}

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

}

Remember, all annotation is from javax.persistence.* and not from org.hibernate.*
Little explanation,
@Entity is always used if you want the class to be recognize by hibernate
@Table is used when your class name isn’t the same with your table name
@Id is always used because hibernate think this is a mandatory
@Column is used if your field variable differ than your field column

Here i use @GeneratedValue because i had a sequence in my table to fill my ID column.

Next is to create simple class to test save and load method.
public class HibernateTest {
private static final Logger logger = Logger.getLogger(HibernateTest.class);
public static void main(String[] args){
AnnotationConfiguration ac = new AnnotationConfiguration();
Session session = ac.configure().buildSessionFactory().openSession();

List list = new ArrayList();

Transaction tx = session.beginTransaction();
for(int i=0;i<10;i++){
Unit u = new Unit();
u.setId((i+50000));
u.setName(“@”+i);
u.setLocation(“Badak”);
u.setCreateBy(“12345″);
session.save(u);
}
session.flush();
tx.commit();

list = session.createQuery(“from Unit u where u.location=:loc and u.name like ‘@%’”)
.setString(“loc”, “Badak”)
.list();

logger.debug(“list size = “+list.size());
for (Unit object : list) {
logger.debug(“Unit = “+object.getName());
}
}
}

What to choose?

gunnasatria — Tue, 30 Oct 2007 14:19:57 +0000

I am now in the phase of design and analysis of a software project. So i have to choose what should i use in this project.
For the presentation layer my candidates are Tapestry 3.0.3(because i don’t want to use Tap 5 who is still in alpha), ZeroKode (based from my recent experience) and Webwork (which i use in my last project).
I try ZK in the first place, and after a while i decide not to use it because of my lack of experience with this framework and the fact that i am working this project with my co-worker who only familiar with Tapestry, so goes out ZK. And without considering Webwork for the same reason, i choose Tapestry.
I use Spring as the middle layer to manage the beans. Because… it’s a clear choice
Last is to choose the DAO layer.
The options are Hibernate, Ibatis or just simple JDBC. It’s a hard choice, i want a powerful tool but i don’t want to write too much of xmls, Tapestry 3 already have much xml to write.
I almost choose JDBC as my DAO layer, but then i read something in Spring 2 in Action.

…When we were kids, riding a bike was fun, wasn’t it? We would ride to school in the
mornings. When school let out, we would cruise to our best friend’s house. When
it got late and our parents were yelling at us for staying out past dark, we would
peddle home for the night. Gee, those days were fun.
Then we grew up and we needed more than a bike. Sometimes we have to
travel quite a distance to work. Groceries have to be hauled, and ours kids need to
get to soccer practice. And if you live in Texas, air-conditioning is a must! Our
needs have simply outgrown our bike.
JDBC is the bike of the persistence world. It is great for what it does, and for
some jobs it works just fine. But as our applications become more complex, so do
our persistence requirements. We need to be able to map object properties to
database columns and have our statements and queries created for us, freeing us
from typing an endless string of question marks…

So finally i see the option, Hibernate 3 with Annotation. Powerful tool yet less xml.
May all the choices were right and i can complete my project in 9 week.

(Not) Simple JSF+Spring

gunnasatria — Mon, 22 Oct 2007 14:14:20 +0000

I don’t know why but suddenly i want to take a look of this framework. So, i search some jsf tutorial and download jsf distribution framework (jsf 1.2) . I create a simple hello world project using my eclipse ide after following instruction from the tutorial i found. try running it using jetty 5 and the result is it didn’t work..
i found java.lang.NoClassDefFoundError: javax/el/ELResolver error.
Search in google, found out that jetty doesn’t work with jsf. So okay i said, try use tomcat.. but again the result is the same error. Again googling search for answer.. then i found that we have to use glassfish. So i download, install and start up glassfish.
We have to package our project to a war file to deploy, so i create a simple build.xml file to war the package.

After the war file deployed, i try to open the page i have created, index.jsp
Again…error in the page. org.apache.jasper.JasperException: java.lang.RuntimeException: Cannot find FacesContext
“What is this?”, i say.. so hard just want to see a hello world message in your page..
So, again i ask google. After a long and almost gave up process, i found a silly mistake. This is my web.xml code

PUBLIC “-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN”
“http://java.sun.com/dtd/web-app_2_3.dtd”>

contextConfigLocation
/WEB-INF/applicationContext.xml

org.springframework.web.context.ContextLoaderListener

org.springframework.web.context.request.RequestContextListener

Faces Servlet
javax.faces.webapp.FacesServlet
1

Faces Servlet
*.jsf

I finally noticed that my url pattern is *.jsf, so i type http://localhost:8080/jsfsimple/index.jsf and it finally show.. a nice hello world message.

xampp

gunnasatria — Thu, 18 Oct 2007 07:45:32 +0000

Are you familiar with PHPTriad in windows? Well you can get the same one for linux. Auto install apache,php,mysql and phpmyadmin. But becarefull, must configure phpmyadmin security first.. because it has a blank password in default installation. You can get xampp here.

Map Windows from Linux

gunnasatria — Thu, 18 Oct 2007 07:38:40 +0000

We usually map linux share from windows using samba. Not the other way around. But i learn today that it can be done. We can use Sharity to do that.The configuration is very easy. All you have to do is extract the package on your linux. And run the application. For you who like GUI(like I do), there is one so don’t worry.
After you run the application, enter your windows share, and your folder in linux file system as the mount destination.
For the free version we can only mount one share at a time. It’s okay for me though