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Getting the name of the requesting page

Ravi Sree

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posted 14 years ago

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Hi all,

I am working on a project which uses MVC 2 approach.
View - HTML and JSP, Controller- a servlet, Model - beans,
business and data access layer, etc.
I want to populate the view data as a (form)bean.
i tried with common setProperty and getProperty but
using wasnt very satisfied as the useBean facility works in session scope.
but not as required (as per the project) for scope request as in struts framework.
hence I am trying to build the (form)bean at the server-side to be easy to process via a filter.
But for that i want to know if address of the page from which the request is generated can be determined.
Please reply if this is right, and if there is any other alternative.

Thanks in advance.

Ravi Sree

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posted 14 years ago

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Hi again,

This is the example i tried out for passing form parameters to the servlet from jsp

MyServlet.jsp

MyBean.java

web.xml

index.jsp

result

This is one of my steps where i could make a thorough understanding of a MVC 2 architecture.
Please suggest where am i going wrong and what should be done here, so as to get the form parameter in request scope in the itself servlet end,
I had read something about common.beanUtils but havent used it yet.
I will be very thankful if any solution, example, or links are provided.

Thanks in advance.

William Brogden

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posted 14 years ago

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How is the request expected to get a reference to your bean? Where is the setAttribute code?

What does JSP have to do with anything here? JSP writes a HTML page to the client browser, if that includes a FORM which does a POST to the servlet, you can only get String values from the request parameters.

Bill

Ravi Sree

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William Brogden wrote: MyBean myBean = (MyBean) req.getAttribute("myBean");

How is the request expected to get a reference to your bean? Where is the setAttribute code?

What does JSP have to do with anything here? JSP writes a HTML page to the client browser, if that includes a FORM which does a POST to the servlet, you can only get String values from the request parameters.

Bill

Hi William,

Thanks for replying.

I intended to pass the form parameter data using useBean, and expecting it to get in th request scope at the servlet end.
Hence the form parameters assinging to the properties with <jsp:setProperty name="myBean" property="*"/>
Please suggest if there is any other way by which i can assign the parameters to the form bean in jsp in request scope to be accessed by the servlet(controller).

Bear Bibeault

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You can't.

The request that generates the HTML page created by the JSP goes away when the response is sent to the browser. So any scoped variables in request scope go away with it.

You can only submit form elements from the page back to the server. So you can capture the data in hidden form elements if that's appropriate.

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Ravi Sree

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Bear Bibeault wrote:You can't.

The request that generates the HTML page created by the JSP goes away when the response is sent to the browser. So any scoped variables in request scope go away with it.

You can only submit form elements from the page back to the server. So you can capture the data in hidden form elements if that's appropriate.

Hi Bear,

Thanks for replying,

What i want to do is keep the form parameter in request scope.
Since as you said, this scoped variable is not able to persist the data,
And assigning them to session scope is not a very appropriate way,
since I plan to save only data as username, etc in session object.
I though of using the ServletFilter as alternative way, where i thought of
recognizing the url from which the request was generated accordingly map parameters
in the bean class and assigning them in request scope (so the subject of the question, please don't mind).
But could think of a good way to do that too.

I did some study with struts source code, but was not very comfortable with
going for designing tags for the same as it it seems in struts1.2.9.

This isn't the actual project i am working on,
The project contains HttpServlet as the controller which analyses the url (for eg: "/user/Register")
and passes the control to appropriate action which has the calls the business layer which
in turn may call data access layer and as per the result returns the url as string which the servlet
uses to forward using normal request dispatcher.
As of now i am using the Form parameters as in a Hash map as opposed to in a bean,
Hence to add another level of effectiveness as per the MVC2 approach beans has to be
the carriers of the data in every level, i am looking for the simple but most effective solution.

Please suggest if any other way is there.

Bear Bibeault

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To be honest, after reading this topic through, I'm still not sure what you are really trying to accomplish.

If all you want to do is to pre-populate a form with values, that's pretty striaght-forward and doesn't require all the complications methioned in this topic.

So what are actually trying to do?

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Ravi Sree

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Bear Bibeault wrote:To be honest, after reading this topic through, I'm still not sure what you are really trying to accomplish.

If all you want to do is to pre-populate a form with values, that's pretty striaght-forward and doesn't require all the complications methioned in this topic.

So what are actually trying to do?

Hi,

That was just the project design i am working on

Please let me explain with an example :

web.xml

FormBean.java

package foo;

import java.util.*;

public class FormBean
{
	private String firstName;
	private String lastName;
	private String email;
	private String userName;
	private String password1;
	private String password2;
	private String zip;
	private String[] faveMusic;
	private String notify;
	private Hashtable errors;

public boolean validate()
	{
		boolean allOk=true;
		if (firstName.equals(""))
		{
			errors.put("firstName","Please enter your first name");
			firstName="";
			allOk=false;
		}
		if (lastName.equals(""))
		{
			errors.put("lastName","Please enter your last name");
			lastName="";
			allOk=false;
		}
		if (email.equals("") || (email.indexOf('@') == -1))
		{
			errors.put("email","Please enter a valid email address");
			email="";
			allOk=false;
		}
		if (userName.equals(""))
		{
			errors.put("userName","Please enter a username");
			userName="";
			allOk=false;
		}
		if (password1.equals("") )
		{
			errors.put("password1","Please enter a valid password");
			password1="";
			allOk=false;
		}
		if (!password1.equals("") && (password2.equals("") || !password1.equals(password2)))
		{
			errors.put("password2","Please confirm your password");
			password2="";
			allOk=false;
		}
		if (zip.equals("") || zip.length() !=5 )
		{
			errors.put("zip","Please enter a valid zip code");
			zip="";
			allOk=false;
		}
		else
		{
			try
			{
			      int x = Integer.parseInt(zip);
			}
		     	catch (NumberFormatException e)
			{
				errors.put("zip","Please enter a valid zip code");
				zip="";
				allOk=false;
			}
		}
		return allOk;
	}

public String getErrorMsg(String s)
	{
		String errorMsg =(String)errors.get(s.trim());
		return (errorMsg == null) ? "":errorMsg;
	}

public FormBean()
	{
		firstName="";
		lastName="";
		email="";
		userName="";
		password1="";
		password2="";
		zip="";
		faveMusic = new String[] { "1" };
		notify="";
		errors = new Hashtable();
	}
	
	public String getFirstName()
	{ return firstName;}

public String getLastName()
	{ return lastName; }

public String getEmail()
	{ return email; }

public String getUserName()
	{ return userName; }

public String getPassword1()
	{ return password1; }
	
	public String getPassword2()
	{ return password2; }

public String getZip()
	{ return zip; }
	
	public String getNotify()
	{ return notify; }

public String[] getFaveMusic()
	{ return faveMusic; }

public String isCbSelected(String s)
	{ 
		boolean found=false;
		if (!faveMusic[0].equals("1"))
		{
			for (int i = 0; i < faveMusic.length; i++)
			{
				if (faveMusic[i].equals(s))
				{
					found=true;	
					break;
				}
			}
			if (found)
				return "checked";
		}
		return "";
   	}
	
	public String isRbSelected(String s)
	{
		return (notify.equals(s))? "checked" : "";
	}

public void setFirstName(String fname)
	{ firstName = fname; }

public void setLastName(String lname)
	{ lastName =lname; }

public void setEmail(String eml)
	{ email=eml; }

public void setUserName(String u)
	{ userName=u; }

public void  setPassword1(String p1)
	{ password1=p1; }

public void  setPassword2(String p2)
	{ password2=p2; }

public void setZip(String z)
	{ zip=z; }

public void setFaveMusic(String[] music)
	{ faveMusic=music; }

public void setErrors(String key, String msg)
	{	
		errors.put(key,msg);
	}

public void setNotify(String n)
	{
		notify=n;
	}
}

DBHandler.java

package net;

import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;

import foo.FormBean;

public class DBHandler extends HttpServlet
{
	public void doPost (HttpServletRequest request, HttpServletResponse response)
	{
		try
		{
			FormBean f = (FormBean) request.getAttribute("formHandler"); 
			boolean userExists = false;

//obtain a db connection and perform a db query 
			//ensuring that the username does not exist
			//set userExists=true if user is found in db

//for a simple test, you can disallow the registration
			//of the username "rogerm" as:
			//if (f.getUserName().equals("rogerm")) userExists=true;

if (userExists)
			{
				f.setErrors("userName","Duplicate User: Try a different username"); 
				getServletConfig().getServletContext().getRequestDispatcher("/jsp/forms/retry.jsp").forward(request, response);
			}
			else
			{
				//retrieve the bean properties and store them
				// into the database. 
				getServletConfig().getServletContext().getRequestDispatcher("/jsp/forms/success.jsp").forward(request, response);
			}
		}
		catch (Exception ex)
		{
			ex.printStackTrace();
		}
	}
}

forms.properties

process.jsp

retry.jsp

<jsp:useBean id="formHandler" class="foo.FormBean" scope="request"/>
<html> 
<body>
<form action="process.jsp" method=post>
<center>
<table   border=0>
<th  >
<font size=5>USER REGISTERATION</font>
<br>
<font size=1><sup>*</sup> Required Fields </font>
</th>
<tr >
<td > 
<B>First Name<sup>*</sup></B> 
<br>
<input type="text" name="firstName" value='<%=formHandler.getFirstName()%>' size=15 maxlength=20>
<br><font size=2 color=red><%=formHandler.getErrorMsg("firstName")%></font>
</td>
<td  >
<B>Last Name<sup>*</sup></B>
<br>
<input type="text" name="lastName" value='<%=formHandler.getLastName()%>' size=15 maxlength=20>
<br><font size=2 color=red><%=formHandler.getErrorMsg("lastName")%></font>
</td>
</tr>
<tr >
<td >
<B>E-Mail<sup>*</sup></B> 
<br>
<input type="text" name="email" value='<%=formHandler.getEmail()%>' size=25  maxlength=125>
<br><font size=2 color=red><%=formHandler.getErrorMsg("email")%></font>
</td>
<td  >
<B>Zip Code<sup>*</sup></B> 
<br>
<input type="text" name="zip" value='<%=formHandler.getZip()%>' size=5  maxlength=5>
<br><font size=2 color=red><%=formHandler.getErrorMsg("zip")%></font>
</td>
</tr>
<tr >
<td  > 
<B>User Name<sup>*</sup></B>
<br>
<input type="text" name="userName" size=10 value='<%=formHandler.getUserName()%>'  maxlength=10>
<br><font size=2 color=red><%=formHandler.getErrorMsg("userName")%></font>
</td>
</tr>
<tr >
<td >
<B>Password<sup>*</sup></B> 
<br>
<input type="password" name="password1" size=10 value='<%=formHandler.getPassword1()%>'  maxlength=10>
<br><font size=2 color=red><%=formHandler.getErrorMsg("password1")%></font>
</td>
<td  >
<B>Confirm Password<sup>*</sup></B>
<br>
<input type="password" name="password2" size=10 value='<%=formHandler.getPassword2()%>'  maxlength=10>
<br><font size=2 color=red><%=formHandler.getErrorMsg("password2")%></font>
</td>
<br>
</tr>
<tr >
<td  >
<B>What music are you interested in?</B>
<br>
<input type="checkbox" name="faveMusic" value="Rock" ><%=formHandler.isCbSelected("Rock")%>>Rock    
<input type="checkbox" name="faveMusic" value="Pop" ><%=formHandler.isCbSelected("Pop")%>>Pop  
<input type="checkbox" name="faveMusic" value="Bluegrass" ><%=formHandler.isCbSelected("Bluegrass")%>>Bluegrass<br>
<input type="checkbox" name="faveMusic" value="Blues" ><%=formHandler.isCbSelected("Blues")%>>Blues  
<input type="checkbox" name="faveMusic" value="Jazz" ><%=formHandler.isCbSelected("Jazz")%>>Jazz  
<input type="checkbox" name="faveMusic" value="Country" ><%=formHandler.isCbSelected("Country")%>>Country<br>
</td>
</tr>
<tr >
<td  >
<B>Would you like to receive e-mail notifications on our special sales?</B>
<br>
<input type="radio" name="notify" value="Yes" ><%=formHandler.isRbSelected("Yes")%>>Yes       
<input type="radio" name="notify" value="No" ><%=formHandler.isRbSelected("No")%>> No 
<br><br></td>
</tr>
<tr >
<td  >
<input type="submit" value="Submit"> <input type="reset"  value="Reset">
</td>
</tr>
</table>
</center>
</form>
</body>
</html>

success.jsp

<jsp:useBean id="formHandler" class="foo.FormBean" scope="request"/>
<html>
<body>
<center>
<table   border=0>
<th  >
<font size=5>USER REGISTERATION SUCCESSFUL!</font>
</th>
<font size=4>
<tr >
<td > 
<b>First Name</b> 
<br>
<jsp:getProperty name="formHandler" property="firstName"/>
</td>
<td >
<b>Last Name</b>
<br>
<jsp:getProperty name="formHandler" property="lastName"/>
</td>
</tr>
<tr >
<td >
<b>E-Mail</b> 
<br>
<jsp:getProperty name="formHandler" property="email"/>
<br></td>
<td >
<b>Zip Code</b> 
<br>
<jsp:getProperty name="formHandler" property="zip"/>
</td>
</tr>
<tr >
<td  >
<b>User Name</b>
<br>
<jsp:getProperty name="formHandler" property="userName"/>
</td>
</tr>
<tr >
<td  >
<b>What music are you interested in?</b>
<br>
<%
	String[] faveMusic = formHandler.getFaveMusic();
	if (!faveMusic[0].equals("1")) {
		out.println("<ul>");
		for (int i=0; i<faveMusic.length; i++)  
			out.println("<li>"+faveMusic[i]);
		out.println("</ul>");
	} else out.println("Nothing was selected");
%>
</td>
</tr>
<tr >
<td  >
<b>Would you like to receive e-mail notifications on our special sales?</b>
<br>
<jsp:getProperty name="formHandler" property="notify"/>
</td>
</tr>
</font>
</table>
</center>
</body>
</html>

I want to do this kind of form processing but without using process.jsp as in this example.
Although i went through few of the struts source code, havent fully understood
how the parameters are bound to the form-bean (Action-Form) after submitting the form.
I was hoping if this kind of form processing can be done,
even though if it may not be an easy task for wrting a generic method to bind the form parameters .
so that the controller's 'Action' can use the bean in request itself.

Please bear with me and guide if my understanding is not right.

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