Java Tips and Tricks: November 2012

Wednesday, 21 November 2012

JQuery Validate Plugin

Validating forms

You need a standard library of validation methods (think of emails, URLs, credit card numbers). You need to place error messages in the DOM and show and hide them when appropriate. You want to react to more than just a submit event, like key up and blur. You may need different ways to specify validation rules, based on the server-side enviroment you are using on different projects.

Example

Source Code:-

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
                    "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script type="text/javascript" src="http://jzaefferer.github.com/jquery-validation/jquery.validate.js"></script>
<style type="text/css">
* { font-family: Verdana; font-size: 96%; }
label { width: 10em; float: left; }
label.error { float: none; color: red; padding-left: .5em; vertical-align: top; }
p { clear: both; }
.submit { margin-left: 12em; }
em { font-weight: bold; padding-right: 1em; vertical-align: top; }
</style>
<script>
$(document).ready(function(){
    $("#commentForm").validate();
});
</script>

</head>
<body>
<form class="cmxform" id="commentForm" method="get" action="">
<fieldset>
   <legend>A simple comment form with submit validation and default messages</legend>
   <p>
<label for="cname">Name</label>
<em>*</em><input id="cname" name="name" size="25" class="required" minlength="2" />
   </p>
   <p>
<label for="cemail">E-Mail</label>
<em>*</em><input id="cemail" name="email" size="25" class="required email" />
</p>
<p>
   <label for="curl">URL</label>
   <em> </em><input id="curl" name="url" size="25" class="url" value="" />
</p>
   <p>
   <label for="ccomment">Your comment</label>
   <em>*</em><textarea id="ccomment" name="comment" cols="22" class="required"></textarea>
   </p>
   <p>
     <input class="submit" type="submit" value="Submit"/>
   </p>
</fieldset>
</form>
</body>
</html>

Validating a comment form.

$("#commentForm").validate();

Options for the validate() method

method: A validation method implements the logic to validate an element, like an email method that checks for the right format of an text input's value. A set of standard methods is available, and it is easy to write your own.
rule: A validation rule associates an element with a validation method, like "validate input with name "primary-mail" with methods "required" and "email".

For a start, the validate-method:

Plugin methods

Plugin methods:

validate( options )	Returns: Validator
Validates the selected form.
valid( )	Returns: Boolean
Checks whether the selected form is valid or whether all selected elements are valid.
rules( )	Returns: Options
Return the validations rules for the first selected element.
rules( "add", rules )	Returns: Options
Adds the specified rules and returns all rules for the first matched element. Requires that the parent form is validated, that is, $("form").validate() is called first.
rules( "remove", rules )	Returns: Options
Removes the specified rules and returns all rules for the first matched element.
removeAttrs( attributes )	Returns: Options
Remove the specified attributes from the first matched element and return them.

Custom selectors

Custom selectors:

:blank	Returns: Array<Element>
Matches elements with a blank value
:filled	Returns: Array<Element>
Matches elements with a value.
:unchecked	Returns: Array<Element>
Matches all elements that are unchecked.

Validator

The validate method returns a Validator object that has a few public methods that you can use trigger validation programmatically or change the contents of the form. The validator object has more methods, but only those documented here are intended for usage.

Validator methods:

form( )	Returns: Boolean
Validates the form, returns true if it is valid, false otherwise.
element( element )	Returns: Boolean
Validates a single element, returns true if it is valid, false otherwise.
resetForm( )	Returns: undefined
Resets the controlled form.
showErrors( errors )	Returns: undefined
Show the specified messages.
numberOfInvalids( )	Returns: Integer
Returns the number of invalid fields.

There are a few static methods on the validator object:

Validator functions:

setDefaults( defaults )	Returns: undefined
Modify default settings for validation.
addMethod( name, method, message )	Returns: undefined
Add a custom validation method. It must consist of a name (must be a legal javascript identifier), a javascript based function and a default string message.
addClassRules( name, rules )	Returns: undefined
Add a compound class method - useful to refactor common combinations of rules into a single class.
addClassRules( rules )	Returns: undefined
Add compound class methods - useful to refactor common combinations of rules.

List of built-in Validation methods

A set of standard validation methods is provided:

Methods:

required( )	Returns: Boolean
Makes the element always required.
required( dependency-expression )	Returns: Boolean
Makes the element required, depending on the result of the given expression.
required( dependency-callback )	Returns: Boolean
Makes the element required, depending on the result of the given callback.
remote( options )	Returns: Boolean
Requests a resource to check the element for validity.
minlength( length )	Returns: Boolean
Makes the element require a given minimum length.
maxlength( length )	Returns: Boolean
Makes the element require a given maxmimum length.
rangelength( range )	Returns: Boolean
Makes the element require a given value range.
min( value )	Returns: Boolean
Makes the element require a given minimum.
max( value )	Returns: Boolean
Makes the element require a given maximum.
range( range )	Returns: Boolean
Makes the element require a given value range.
email( )	Returns: Boolean
Makes the element require a valid email
url( )	Returns: Boolean
Makes the element require a valid url
date( )	Returns: Boolean
Makes the element require a date.
dateISO( )	Returns: Boolean
Makes the element require a ISO date.
number( )	Returns: Boolean
Makes the element require a decimal number.
digits( )	Returns: Boolean
Makes the element require digits only.
creditcard( )	Returns: Boolean
Makes the element require a creditcard number.
accept( extension )	Returns: Boolean
Makes the element require a certain file extension.
equalTo( other )	Returns: Boolean
Requires the element to be the same as another one

Warning:-

Too much recursion

Another common problem occurs with this code:

$("#myform").validate({
 submitHandler: function(form) {
   // some other code
   // maybe disabling submit button
   // then:
   $(form).submit();
 }
});

This results in a too-much-recursion error: $(form).submit() triggers another round of validation, resulting in another call to submitHandler, and voila, recursion. Replace that with form.submit(), which triggers the native submit event instead and not the validation.
So the correct code looks slightly different:

$("#myform").validate({
 submitHandler: function(form) {
   form.submit();
 }
});

Tuesday, 20 November 2012

Servlet Configuration - Web.xml

For a Java servlet to be accessible from a browser, you must tell the servlet container what servlets to deploy, and what URL's to map the servlets to. This is done in the web.xml file of your Java web application.
Here is a list of the topics covered in this blog about the web.xml servlet configuration:

Configuring and Mapping a Servlet
Servlet Init Parameters
Servlet Load-on-Startup
Context Parameters

Configuring and Mapping a Servlet

To configure a servlet in the web.xml file, you write this:

<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app

    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"

    "http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>

  <servlet>

    <servlet-name>controlServlet</servlet-name>

    <servlet-class>com.jenkov.butterfly.ControlServlet</servlet-class>

  </servlet>

  <servlet-mapping>

    <servlet-name>controlServlet</servlet-name>

    <url-pattern>*.html</url-pattern>

  </servlet-mapping>

</web-app>

First you configure the servlet. This is done using the <servlet> element. Here you give the servlet a name, and writes the class name of the servlet.
Second, you map the servlet to a URL or URL pattern. This is done in the <servlet-mapping> element. In the above example, all URL's ending in .html are sent to the servlet.
Other possible servlet URL mappings are:

/myServlet

/myServlet.do

/myServlet*

The * is a wild card, meaning any text. As you can see, you can either map a servlet to a single, specific URL, or to a pattern of URL's, using a wild card (*). What you will use depends on what the servlet does.

Servlet Init Parameters

You can pass parameters to a servlet from the web.xml file. The init parameters of a servlet can only be accessed by that servlet. Here is how you configure them in the web.xml file:

<servlet>

    <servlet-name>controlServlet</servlet-name>

    <servlet-class>com.jenkov.butterfly.ControlServlet</servlet-class>

    <init-param>

        <param-name>myParam</param-name>

        <param-value>paramValue</param-value>

    </init-param>

</servlet>

Here is how you read the init parameters from inside your servlet - in the servlets init() method:

public class SimpleServlet extends GenericServlet {

  protected String myParam = null;

  public void init(ServletConfig servletConfig) throws ServletException{

    this.myParam = servletConfig.getInitParameter("myParam");

  public void service(ServletRequest request, ServletResponse response)

        throws ServletException, IOException {

    response.getWriter().write("<html><body>myParam = " +

            this.myParam + "</body></html>");

A servlets init() method is called when the servlet container loads the servlet for the first time. No one can access the servlet until the servlet has been loaded, and the init() method has been called successfully.

Servlet Load-on-Startup

The `<servlet>` element has a subelement called `<load-on-startup>` which you can use to control when the servlet container should load the servlet.

`<load-on-startup>` tag specifies that the servet should be loaded automatically when the web application is started. when loaded, the init() method of the servlet is called.

If you do not specify a <load-on-startup> element, the servlet container will typically load your servlet when the first request arrives for it.

Here is an example <load-on-startup> configuration:

<servlet>

    <servlet-name>controlServlet</servlet-name>

    <servlet-class>com.jenkov.webui.ControlServlet</servlet-class>

    <init-param><param-name>container.script.static</param-name>

                <param-value>/WEB-INF/container.script</param-value>

    </init-param>

    <load-on-startup>1</load-on-startup>

</servlet>

The number inside the <load-on-startup>1</load-on-startup> element tells the servlet container in what sequence the servlets should be loaded. The lower numbers are loaded first. If the value is negative, or unspecified, the servlet container can load the servlet at any time.

Context Parameters

You can also set some context parameters which can be read from all servlets in your application. Here is how you configure a context parameter:

<context-param>

    <param-name>myParam</param-name>

    <param-value>the value</param-value>

</context-param>

Here is how you access the parameter from inside an HttpServlet subclass:

String myContextParam =

        request.getSession()

               .getServletContext()

               .getInitParameter("myParam");

Tuesday, 13 November 2012

JQuery Sample Example

GETTING JAVA

Create an application to maintain employee details. This application should support the following functionalities:

1. Create new employees.

1.1 Must Validate the mandatory fields

1.2 Employee code should be unique

1.3 Date format should be dd/mm/yyyy format

2. View/Modify the added employees

2.1 Employee code should be unique

3. Delete employees

4. Change priority of employees

The employee information includes the following:

No	Name of the field	Size	Details
1	EMPLOYEE CODE	10	§ This field is mandatory § This field cannot be repeated
2	NAME	256	§ This field is mandatory
3	DOB		§ This field is mandatory § The format should be dd/mm/yyyy
4	ADDRESS		§ This field is mandatory
5	STATE	100
6	LANGUAGE	256
7	SEX	2
8	PUBLISH	2	§ This field is to determine whether data should be published in the public part

Screenshots

1 Add Employee Details

2 Edit Employee Details

3 Employee List

4 Delete / Edit Employee

Technologies

1) Languages : JSP, HTML, Ajax, JQuery, JavaScript

2) Database : MySql 5

DATABASE : training

USERNAME : root

PASSWORD : root

URL : 192.168.0.11:3306/training

3) IDE : Eclipse 3.4, SQLyog

Screen Database Relation

NO:	Screen Field	Table Name	FIELD	TYPE
1		tab_employee	emp_id	int
2	EMPLOYEE CODE	tab_employee	emp_code	varchar
3	NAME	tab_employee	emp_name	varchar
4	DOB	tab_employee	date_of_birth	date
5	ADDRESS	tab_employee	emp_address	text
6	STATE	tab_employee	emp_state	varchar
7	LANGUAGE	tab_employee	emp_language	varchar
8	SEX	tab_employee	emp_sex	smallint
9		tab_employee	emp_priority	int
10	PUBLISH	tab_employee	emp_publish	smallint

Database Model

TABLE : tab_employee

NO:	FIELD	TYPE	SIZE
1	emp_id	int	11
2	emp_code	varchar	10
3	emp_name	varchar	256
4	date_of_birth	date
5	emp_address	text
6	emp_state	varchar	100
7	emp_language	varchar	256
8	emp_sex	smallint	2
9	emp_priority	int	11
10	emp_publish	smallint	2

JSP PAGES

The main jsp pages used for employee operations are addemployees.jsp , addemployeesdb.jsp, deleteemployees.jsp , ajaxemployees .jsp and employeeslist.jsp

addemployees.jsp

This page is used for both adding and editing the employee’s details. The details entered by the user in this page will be validated first. If the user didn’t enter valid data, then error message will be shown at the top of the page. If all the fields entered are valid, then page is submitted to the addemployeesdb page . if the emp_id is 0, then the mode is ‘add‘ otherwise the page is in edit mode.

only logged in users can view this page .so we check it at the beginning of the page it is checked whether the user had logged in or not

//checking session for logged in user

if(session.getAttribute("logged_in_user") == null) response.sendRedirect("index?ct=" + System.currentTimeMillis());

If the logged in user is null. Then the page will be redirected to the index page.

Validation

In the employee add page employee code, name, date of birth, address, state are mandatory field, the user must enter it. The employee code cannot be repeated and the date must be entered in the specified format. Jquery validations is used to validate this.

The validation is taking place when the user click the submit button .when clicking the submit button function submitForm will be executed

function submitForm(){

-------

} In this first five rules are added to validate the fields employee code, name, dob, address, state as

jQ("#frmAddemply").find(":input[name='emp_code']").rules("add", {required: true});

jQ("#frmAddemply").find(":input[name='emp_name']").rules("add", {required: true});

jQ("#frmAddemply").find(":input[name='emp_dob']").rules("add", {required: true,datecheck: true});

jQ("#frmAddemply").find("#emp_address").rules("add", {required: true});

jQ("#frmAddemply").find(":input[name='emp_state']").rules("add", {required: true});

frmAddemply is the id of the form and ‘required : true’ means this field should not be empty. In the third rule there is ‘required:true, datecheck: true’ which means the field is required and datecheck should be true. We have added datecheck as another function to check the entered date format as dd/mm/yyyy.

jQuery.validator.addMethod("datecheck", function(value, element) {

var vDT="(([012]?[1-9])|10|20|30|31)[/](([0]?[1-9])|10|11|12)[/](19|20)?[0-9]{2}";

var regex = new RegExp(vDT);

return (regex.test(value));

});

If the entered format is correct it will return true otherwise false.

if(jQ("#frmAddemply").validate().element(jQ("#frmAddemply").find(":input[name='emp_code']"))){

if(jQ("#frmAddemply").validate().element(jQ("#frmAddemply").find(":input[name='emp_name']"))) {

if(jQ("#frmAddemply").validate().element(jQ("#frmAddemply").find(":input[name='emp_dob']"))) {

if(jQ("#frmAddemply").validate().element(jQ("#frmAddemply").find("#emp_address"))){

if(jQ("#frmAddemply").validate().element(jQ("#frmAddemply").find(":input[name='emp_state']"))) {

checkDuplicateCode();

}else{

jQ("#emp_state").addClass("invalid_form_element");

}

}else{

jQ("#emp_address").addClass("invalid_form_element");

}

}else{

jQ("#emp_dob").addClass("invalid_form_element");

}

}else{

jQ("#emp_name").addClass("invalid_form_element");

}

}else{

jQ("#emp_code").addClass("invalid_form_element");

}

Based on the added rules all four fields are checked to see if it return true. If it does not return true then else condition will execute and a red line will appear the border of that field to indicate error condition.

jQ('#frmAddemply').validate({

messages: {

"emp_code" : {

required: "Please Enter Code"

"emp_name" : {

required: "Please Enter Name"

"emp_dob" : {

required: "Please Enter DOB",

datecheck: "Enter Correct Format (dd/mm/yyyy)"

"emp_address" : {

required: "Please Enter Address"

"emp_state" : {

required: "Please Enter State"

}

errorPlacement : function(error, element) {

viewMessageText(error.text());

}

});

The above code is included in the jquery ready function. This is for displaying the error message on top of the page. frmAddemply is the id of the form

Eg: if emp_code is empty, then the message ‘please Enter code’ will be displayed on top of the page through the function

Function viewMessageText(msgText) {

if(msgText != '') {

jQ('#notifyDiv').css("display", "block");

jQ('#notifyPar').html(msgText);

}

If all data entered are valid, then the function checkDuplicateCode() is executed to check the added employee code already exist or not .

function checkDuplicateCode(){

var value = document.frmAddemply.emp_code.value;

var empId = '<%=emp_id%>'

jQ.ajax({

type: "POST",

url : "ajaxemploy",

data:"fun=checkEmpcode&code="+value+"&emp_id="+empId ,

success: function(data, status) {

var responseHtml = data.trim();

if(responseHtml.indexOf("OK") != -1) {

jQ('#frmAddemply').submit();

}

else {

viewMessage(1);

}

error: function(xml, status, e){queryError(xml, status, e)},

global: false

});

}

This will make an ajax call to the ajaxemploy.jsp page and there checking is done. if value already exist KO will be returned otherwise OK will be returned . If the returned value is OK, then the form will be submitted otherwise viewMessage(1) is called

var messages = new Array();

messages[1] = "Employee Code already exist";

and this message will be displayed

If the emp_id is not 0, then the form will be in edit mode. Then the save button will be changed to a modify one.

if(!emp_id.equals("0")){

psEmp=conn.prepareStatement("SELECT emp_name, date_of_birth, emp_address, emp_state, emp_language, emp_sex, emp_publish, emp_code FROM tab_employee WHERE emp_id=?");

psEmp.clearParameters();

psEmp.setInt(1,Integer.parseInt(emp_id));

rsEmp=psEmp.executeQuery();

if(rsEmp.next()){

emp_name=rsEmp.getString(1);

emp_dob=sdf.format(rsEmp.getDate(2));

emp_address=rsEmp.getString(3);

emp_state=rsEmp.getString(4);

emp_language=rsEmp.getString(5);

emp_sex=rsEmp.getString(6);

emp_publish=rsEmp.getString(7);

emp_code=rsEmp.getString(8);

}

mode="edit";

}

The query will be executed and the corresponding data will be stored in fields like emp_name, emp_code, emp_address, emp_state etc. These fields will be given as values in the corresponding form elements. When the modify button is clicked same validation explained above will happen and the form will be submitted.

Ready function

In javascript the first function executed will be the ready function

jQ(document).ready(function() {

----

---

}

jQ("#btnSubmit").click(function(){

submitForm();

return false;

}); when the id btnSubmit of button is clicked, function submitForm is called.

jQ('#emp_code').focus(); // for focusing the field

addemployesdb.jsp

In this page the data entered in the addemployee will be stored in the database. The two operations done in this page are adding data and modifying it.

if(mode.equals("add")){

int priority;

rsPriority=dbMgr.executeQuery("SELECT MAX(emp_priority) from tab_employee ");

if(rsPriority.next()){

priority=(rsPriority.getInt(1)+1);

}else{

priority= 1;

}

psEmp=conn.prepareStatement("INSERT INTO tab_employee (emp_code, emp_name, date_of_birth, emp_address, emp_state, emp_language, emp_sex, emp_priority, emp_publish) values( ?, ?, ?, ?, ?, ?, ?, ?,?)");

psEmp.setString(1,emp_code);

psEmp.setString(2,emp_name);

psEmp.setDate(3,sqlDate);

psEmp.setString(4,emp_address);

psEmp.setString(5,emp_state);

psEmp.setString(6,emp_language);

psEmp.setInt(7,Integer.parseInt(emp_sex));

psEmp.setInt(8,priority);

psEmp.setInt(9,Integer.parseInt(emp_publish));

psEmp.executeUpdate();

errorCode=1;

}

In this page the data is inserted to the database. The priority inserted will be the maximum priority in that column. The errorCode is used for showing the message

if(mode.equals("edit")){

psEmp=conn.prepareStatement("UPDATE tab_employee SET emp_code=?, emp_name=?,date_of_birth=?,emp_address=?,emp_state=?,emp_language=?,emp_sex=?,emp_publish=? WHERE emp_id=?");

psEmp.setString(1,emp_code);

psEmp.setString(2,emp_name);

psEmp.setDate(3,sqlDate);

psEmp.setString(4,emp_address);

psEmp.setString(5,emp_state);

psEmp.setString(6,emp_language);

psEmp.setInt(7,Integer.parseInt(emp_sex));

psEmp.setInt(8,Integer.parseInt(emp_publish));

psEmp.setInt(9,Integer.parseInt(emp_id));

psEmp.executeUpdate();

errorCode=2;

}

This code is used for updating the details, for this the update query is used. Here priority cannot be updated. This can be done with drag and drop only.

employeeslist.jsp

This page will show the list of employees with details name, dob and code. Different operations like sort, search, modify, delete, change priority can be done.

sqlTopic="SELECT emp_id, emp_name, date_of_birth, emp_priority, emp_publish FROM tab_employee";

rsEmp=dbMgr.executeQuery(sqlTopic+sqlCondition+sqlOrder);

This query will fetch the details of employees and this will displayed on the page by iterating it like

<% while(rsEmp.next()){

-----

<% } %>

Change Priority

Priority can be changed using drag and drop. For this functionality we have to add the script library tablednd.js.

The listing loop should be entered in the div called list border and the table should be given id as ‘employ_table’ and each tr id should be unique values. We also keep a hidden value for identifying each row

----

---------------------------------

<input type="hidden" name="emp_id_<%=prty%>" id="emp_id_<%=prty %>" value="<%=rsEmp.getString("emp_id")%>" />

</tr> <% } %>

</table>

</div>

For the first time when the page loads we will call the js functions as

<%if(boolview){ %>

arrangeList(2,"");

<%}%>

</script> If searching or sorting is done drag and drop should not work. So boolview is there to check that.

Function arrangeList(flag, responseHtml) {

if(flag == 1) {

jQ("#list_border").html(responseHtml);

table1= document.getElementById("employ_table");

if(table1.rows.length > 1) {

tableDnD1 = new TableDnD();

tableDnD1.init(table1);

tableDnD1.onDrop = function (table, row) {

dragMediaUpdate(1, table, row);

}

else if(flag == 2) {

table1= document.getElementById("employ_table");

if(table1.rows.length > 1) {

tableDnD1 = new TableDnD();

tableDnD1.init(table1);

tableDnD1.onDrop = function (table, row) {

dragMediaUpdate(1, table, row);

}

<%}%>

}

For the first time else condition is executed and if the table has more than one rows dragMediaUpdate function is called.

function dragMediaUpdate(flag, table, row) {

var hidObj;

var fromOrder;

var toOrder;

var fun;

if(flag == 1) {

hidObj = document.getElementById("emp_id_"+row.id);

fromOrder = row.id;

toOrder = whichRow(hidObj)+1;

fun = "chngPrty";

}

if(fromOrder != toOrder) {

updateRelatedMediaContent(fun, fromOrder, toOrder)

}

Here the function whichRow is passed the hidden emp_id.

function whichRow(obj){

var par=obj.parentNode;

while(par.nodeName.toLowerCase()!='tr'){

par=par.parentNode;

}

return par.rowIndex;

}

Then if the from order is not equal to the to order function updateRelatedMediaContent() will be called

function updateRelatedMediaContent(fun, fromOrder, toOrder) {

jQ.ajax({

type: "POST",

url: "ajaxemploy",

data: "fun="+fun+"&fromOrder="+fromOrder+"&toOrder="+toOrder+"&ct="+new Date().valueOf(),

success: function(data, status) {

var responseHtml = jQuery.trim(data.trim());

if(responseHtml == 'OK') {

window.location.href = "employeeslist?ct="+new Date().valueOf();

}

error: function(xml, status, e){queryError(xml, status, e)},

global: false

});

}

Here an ajax call is made to the ajaxemploy.jsp with from order and to order are passed as parameters. There the priorities are updated in the database. If the priorities are set correctly, then a response OK is returned otherwise KO is returned. If OK is returned then the page will be refreshed.

The priority can also be changed by clicking the up and down arrow in the list page. In this, the function called is

function moveList(fun, fromOrder, toOrder) {

if(fromOrder != toOrder) {

updateRelatedMediaContent(fun, fromOrder, toOrder)

}

Sorting

The listed fields can sorted in ascending or descending order. This is done with the javascript

function orderBy(orderid, order_field){

jQ('#boolview').attr('value', 'false');

if(jQ('#orderid').attr('value') == orderid) {

if(jQ('#by').attr('value') == 'ASC') {

jQ('#by').attr('value', 'DESC');

} else {

jQ('#by').attr('value', 'ASC');

}

} else {

jQ('#by').attr('value', 'ASC');

}

jQ('#sselValue').attr('value', jQ('#selValue').attr('value'));

jQ('#orderid').attr('value', orderid);

jQ('#orderfield').attr('value', order_field);

jQ('#frm1').attr('action', 'employeeslist?ct=' + new Date().valueOf());

jQ('#frm1').submit();

}

Here the attribute by is set with the value ASC or DESC. Order field will set the name of the column to be ordered. Already the string order by is set as

sqlOrder = " ORDER BY " + orderField + " " + by;

so when query is executed the correct order is executed depending on the situation.

Searching

We can search the employees name in the list when a name is entered in the search field and search button is clicked. The following function is called.

function doSearch() {

jQ('#stitle').attr('value', jQ('#searchtitle').attr('value'));

jQ('#frmlistEmp').attr('action', 'employeeslist?usrType=<%=userType%>&ct=' + new Date().valueOf());

jQ('#frmlistEmp').submit();

}

The search title attribute will keep the value of the search term.

if(!"".equals(exParams.getParameter("searchtitle", ""))) {

sqlCondition += " WHERE UPPER(emp_name) LIKE '%" + dbMgr.parseString(exParams.getParameter("searchtitle", "")).toUpperCase().replaceAll("_", java.util.regex.Matcher.quoteReplacement("\\_")) + "%'";

}

rsEmp=dbMgr.executeQuery(sqlTopic+sqlCondition+sqlOrder);

when this sql condition is executed , we can search the name of the employee.

Modify

An employ data can be modified by clicking the modify link in the employee list. Then page will be redirected to the add employee page. The corresponding employee id is also passed to the page.

Delete

An employee can be deleted by clicking the delete link. When clicked the following javascript function is executed

function doDelete(id,prt){

if(confirm("Do you want to delete the selected item")){

jQ('#emp_id').attr('value', id);

jQ('#prty').attr('value', prt);

jQ('#frmlistEmp').attr('action', 'deleteemploy?ct=' + new Date().valueOf());

jQ('#frmlistEmp').submit();

}

In this script priority and employee id is passed to the deleteemploy .jsp page.

deleteemploy.jsp

In this page the selected employee is deleted and the corresponding priorities are updated.

conn.setAutoCommit(false);// for transaction, either both query will execute or none will execute

psDel=conn.prepareStatement("UPDATE tab_employee SET emp_priority=emp_priority-1 WHERE emp_priority > ? ");

psDel.clearParameters();

psDel.setInt(1,Integer.parseInt(priority));

psDel.executeUpdate();

psDel=conn.prepareStatement("DELETE from tab_employee WHERE emp_id=? ");

psDel.clearParameters();

psDel.setInt(1,Integer.parseInt(emp_id));

psDel.executeUpdate();

conn.commit();

The first query will update the employee and the second query will delete the employee.

ajaxemploy.jsp

In this page ajax related operations are done ie change priority and check duplicate employee code

if(strFun.equals("checkEmpcode")){

String emp_id = exParams.getParameter("emp_id", "0");

String code = exParams.getParameter("code", "0");

int count = 0;

if(emp_id.equals("0")){

String query = "SELECT count(*) FROM tab_employee WHERE emp_code = '"+code+"'";

rsContent = conn.createStatement().executeQuery(query);

if(rsContent.next() ) {

count = rsContent.getInt(1);

}

if(count == 0) {

strBuffer.append("OK");

} else {

strBuffer.append("KO");

}

}else{// For checking code while in edit mode

String query = "SELECT count(*) FROM tab_employee WHERE emp_code = '"+code+"' AND emp_id !="+emp_id;

rsContent = conn.createStatement().executeQuery(query);

if(rsContent.next() ) {

count = rsContent.getInt(1);

}

if(count == 0) {

strBuffer.append("OK");

} else {

strBuffer.append("KO");

}

The above code is used for checking duplicate employee code. If the page is in edit mode , it will check whether any duplicate code exist other than this employee id. If no other code exist OK will be returned otherwise KO will be returned.

change priority

if(strFun.equals("chngPrty")){

String fromOrder = exParams.getParameter("fromOrder", "0");

String toOrder = exParams.getParameter("toOrder", "0");

String sqlQuery = "";

int ok1 = 0;

int ok2 = 0;

int intFrom = Integer.parseInt(fromOrder);

int intTo = Integer.parseInt(toOrder);

selecting the employee id (Employee id and priority will be unique)

String emplyId = "0";

sqlQuery = "SELECT emp_id FROM tab_employee WHERE emp_priority = "+fromOrder +" ";

rsContent = dbMgr.executeQuery(sqlQuery);

if(rsContent.next()) {

emplyId = rsContent.getString(1);

}

if(rsContent != null) rsContent.close();

This code will execute if the from priority is greater than the to priorirty

if(intFrom > intTo) {

String modifyIds = "";

sqlQuery = "SELECT emp_id FROM tab_employee WHERE emp_priority >= "+toOrder+" AND emp_priority < "+fromOrder ;

rsContent = dbMgr.executeQuery(sqlQuery);

while(rsContent.next()) {

if(modifyIds.equals("")) modifyIds = rsContent.getString(1);

else modifyIds += ","+rsContent.getString(1);

}

if(rsContent != null) rsContent.close();

updating all priority by adding one

if(!"".equals(modifyIds)) {

sqlQuery = "UPDATE tab_employee SET emp_priority = emp_priority + 1 WHERE emp_id IN(" + modifyIds + ") ";

ok1 = dbMgr.executeUpdate(sqlQuery);

}

else {

ok1 = 1;

}

This code will execute if the from priority is less than the to priorirty

else if(intFrom < intTo) {

String modifyIds = "";

sqlQuery = "SELECT emp_id FROM tab_employee WHERE emp_priority <= "+toOrder+" AND emp_priority > "+fromOrder ;

rsContent = dbMgr.executeQuery(sqlQuery);

while(rsContent.next()) {

if(modifyIds.equals("")) modifyIds = rsContent.getString(1);

else modifyIds += ","+rsContent.getString(1);

}

if(rsContent != null) rsContent.close();

updating all priority by substracting one

if(!"".equals(modifyIds)) {

sqlQuery = "UPDATE tab_employee SET emp_priority = emp_priority - 1 WHERE emp_id IN(" + modifyIds + ") ";

ok1 = dbMgr.executeUpdate(sqlQuery);

}

else {

ok1 = 1;

}

The to order priority is setting the corresponding employee

sqlQuery = "UPDATE tab_employee SET emp_priority = "+toOrder+" WHERE emp_id = " + emplyId;

ok2 = dbMgr.executeUpdate(sqlQuery);

if(ok1 > 0 && ok2 > 0) {

strBuffer.append("OK");

}

else {

strBuffer.append("KO");

}}

Java Tips and Tricks

About Me

Pages

Wednesday, 21 November 2012

JQuery Validate Plugin

Validating forms

Example

Source Code:-

Options for the validate() method

Plugin methods

Custom selectors

Validator

List of built-in Validation methods

Too much recursion

Tuesday, 20 November 2012

Servlet Configuration - Web.xml

Configuring and Mapping a Servlet

Servlet Init Parameters

Servlet Load-on-Startup

The `<servlet>` element has a subelement called `<load-on-startup>` which you can use to control when the servlet container should load the servlet.

`<load-on-startup>` tag specifies that the servet should be loaded automatically when the web application is started. when loaded, the init() method of the servlet is called.

Context Parameters

Tuesday, 13 November 2012

JQuery Sample Example

Chat with us.

About Me

Pages

Wednesday, 21 November 2012

JQuery Validate Plugin

Validating forms

Example

Source Code:-

Options for the validate() method

Plugin methods

Custom selectors

Validator

List of built-in Validation methods

Too much recursion

Tuesday, 20 November 2012

Servlet Configuration - Web.xml

Configuring and Mapping a Servlet

Servlet Init Parameters

Servlet Load-on-Startup

The <servlet> element has a subelement called <load-on-startup> which you can use to control when the servlet container should load the servlet.

<load-on-startup> tag specifies that the servet should be loaded automatically when the web application is started. when loaded, the init() method of the servlet is called.

Context Parameters

Tuesday, 13 November 2012

JQuery Sample Example

Chat with us.

The `<servlet>` element has a subelement called `<load-on-startup>` which you can use to control when the servlet container should load the servlet.

`<load-on-startup>` tag specifies that the servet should be loaded automatically when the web application is started. when loaded, the init() method of the servlet is called.