How I use DAO

Question

I built a struts application .It is working well.Now I want use DAOand .How I use?
My struts application :
Get the input form user and store it in file or datadase. Here I want to use DAO.
There 6 files .
They are
1.inputname.jsp ----------->used for getting input from client.inputs are mail id and password.
2.GetNameForm.java --------->It is Bean having setter and getter including 2 methods are like filehandler(),dbConnection()(here only implementations).
dbConnection method just sample i did. From MSAccess database, get Age field and print it in tomcat prompt. Here only i have probs.*What probs that I need to use DAO.
3.GreetingAction.java ------>It is servlet and I call FormBean Method
By ((sample.GetNameForm)form).filehandler();
((sample.GetNameForm)form).dBConnection();
String name=((sample.GetNameForm)form).getName();
String pass=((sample.GetNameForm)form).getPass();
Thus I called that methods.
It is good one or Not.
Note. Both java file under the package name is sample.
4.greeting.jsp--------> It is output file which is used to expose the output that mail id and password what we gave.
5.index.jsp---------->It is global forward used to forward client request to inputname.jsp.(It is not a matter to consider with out this file applkication working well.)
5.struts-config.xml file here only direction controls and mapping items and brief links (we know that).
package sample;
import java.io.*;
import java.sql.*;
import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;
public class GetNameForm extends org.apache.struts.action.ActionForm {
private String name="";
private String pass="";
public GetNameForm() {
// TODO: Write constructor body
public void reset(ActionMapping actionMapping, HttpServletRequest request) {
// TODO: Write method body
// throw new UnsupportedOperationException("Method not implemented");
this.name="";
this.pass="";
public ActionErrors validate(ActionMapping actionMapping, HttpServletRequest request) {
// TODO: Write method body
//throw new UnsupportedOperationException("Method not implemented");
ActionErrors errors=new ActionErrors();
if( getName() == null || getName().length() < 1 ) {
errors.add("name",new ActionMessage("error.name.required"));
// actionMapping.findForward("goInput");
if( getPass() == null || getPass().length() < 1 ) {
errors.add("pass",new ActionMessage("error.pass.required"));
// actionMapping.findForward("goInput");
return errors;
public String getName()
return this.name;
public void setName(String name)
this.name=(name==null?"Please Enter The Name":name);
public String getPass()
return this.pass;
public void setPass(String pass)
this.pass=(pass==null?"Please Enter The ID":pass);
public void dBConnection()
Statement st;
Connection con;
ResultSet rs;
try
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
catch(Exception e)
try
con=null;
st=null;
rs=null;
con=DriverManager.getConnection("jdbc:odbc:MSACCESSDSN","","");
st=con.createStatement();
rs=st.executeQuery("Select * from emp ");
while(rs.next())
          int a=rs.getInt("Age");
          System.out.println(a);
catch(Exception e)
public void filehandler() throws IOException
String name=getName();
String pass=getPass();
//Store the Details of User and Password in File
Writer output = null;
try {
//use buffering
File testFile = new File("C:\\gandhi\\mail_det.txt");
BufferedReader input = null;
input = new BufferedReader( new FileReader(testFile) );
StringBuffer Contents=new StringBuffer();
String line=null;
while (( line = input.readLine()) != null)
{System.out.println("From the file value=" +line);
      java.util.StringTokenizer st = new java.util.StringTokenizer(line,"@");
      System.out.println("The file contains data:"+Contents.append(line+"\n"));
     /* System.out.println(st.nextToken("@"));
      while (st.hasMoreTokens()) {
            if( st.equals("name") ){
            name="";
            pass="";
String str=Contents.toString();
System.out.println("The file Contains"+str);
output = new BufferedWriter( new FileWriter(testFile) );
output.write(str+"\n"+name+"\t"+"........."+pass);
finally {
//flush and close both "output" and its underlying FileWriter
if (output != null)
output.close();
This is my Bean How I use DAO replace of dBConnection()
method.
1.What is important of DAO pls explain me with small codings.
2.How I use DAO in this coding?
[Note: I use Exadel StrutsStudio.]
Anyone have idea pls guide me.

Answer 1

Well in a DAO pattern you usually have one DAO class for each table in the database so there is for instance one PersonDAO and one ItemDAO which have their respective create, read, update and delete methods. Each DAO also hides its implementation through an interface defining the DAO methods, furthermore there's a DAO factory determining what class to load at runtime. My advice is to start out simple and not too abstract, try looking at the following example - it involves EJBs but explains the pattern.
http://www.informit.com/guides/printerfriendly.asp?g=java&seqNum=137&rl=1
Also keep in mind that implementing the DAO pattern using frameworks such as Spring simplifies the process, as illustrated here
http://www.java2s.com/Code/Java/Hibernate/SpringDaoDemo.htm
I hope that helps.