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Plz i want help in AJAX

  Asked By: Hisham    Date: Dec 26    Category: Java    Views: 1022
  


I want to Know is there a book i can read and understand AJAX

I finished java web app(jsp,javabeans,sevlet)
if anyone has exprience with AJAX with java, i'd like his advice



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4 Answers Found

 
Answer #1    Answered By: Garry Sanchez     Answered On: Dec 26

use "Manning: Ajax in Action" it's great to begin

 
Answer #2    Answered By: Chung Tran     Answered On: Dec 26

"AJAX, is a group of interrelated web  development techniques used for creating interactive web applications or rich Internet applications." Wikipedia

You can developed your own library basically by extending the foundation techniques of AJAX. I have my extended my own library based on pure Java-Script. Focus on the mechanism rather using 3rd party components and solutions is the key, I think.

Have a look to some parts of the code:
I have selected the simplest part which able you to extend your own Ajax library to solve the problem deeply
for ever. Software solution is separated into two major part:
1.Client-side consists of Java-Script (Ajax routines) and HTML UI components.
2.Server-side which provide Asynchronous request by some simple Servletes.

A part of Java-Script routines is:

function newXMLHttpRequest() {
var xmlreq = false;
if (window.XMLHttpRequest) {
xmlreq = new XMLHttpRequest();
} else if (window.ActiveXObject) {
try {
xmlreq = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e1) {
try {
xmlreq = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e2) {}
}
}
return xmlreq;
}

function getReadyStateHandler(req, responseXmlHandler) {
return function () {
if (req.readyState == 4) {
if (req.status == 200) {
responseXmlHandler(req.responseText);
} else {
alert("HTTP error: " + req.status);
}
}
}
}

function search(sender , domain) {
returnToSender = sender;
var idField = document.getElementById(returnToSender);
if (idField.value.length>1)
{
var url = domain + "Search";
var req = newXMLHttpRequest();
var handlerFunction = getReadyStateHandler(req, callback);
req.onreadystatechange = handlerFunction;
req.open("POST", url , true);
req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
req.send("align="+align+"&lang="+language+"&target=" + encodeURIComponent(idField.value));
}
else
{
fo(0);
fadeOutShort(0);
}
}

function callback(str) {
if (str!="[clear]") {
fadeOutShort(0);
var popupshadow = document.getElementById("popupshadow");
var popup = document.getElementById("popup");
document.getElementById("popupshadow").style.width=380;
document.getElementById("popupshadow").style.height=100;
document.getElementById("popup").style.width=380;
document.getElementById("popup").style.height=100;
popupshadow.innerHTML = "<div><font size=2>"+str+"</font></div>";
popup.innerHTML = "<div><font size=2>"+str+"</font></div>";

var xPos , yPos = 0;
xPos = findPosX(document.getElementById(returnToSender));
yPos = findPosY(document.getElementById(returnToSender));
if (align=="right")
{
xPos = xPos - 165;
}
yPos = yPos + 22;
document.getElementById("popupshadow").style.left = xPos+5;
document.getElementById("popupshadow").style.top = yPos+5;
document.getElementById("popup").style.left = xPos;
document.getElementById("popup").style.top = yPos;
fadeIn(50);
}
else
{
fo(0);
var shortpopup = document.getElementById("shortpopup");
shortpopup.innerHTML = "<div><font size=2>not found.</font></div>";
var xPos , yPos = 0;
xPos = findPosX(document.getElementById(returnToSender));
yPos = findPosY(document.getElementById(returnToSender));
if (align=="right")
{
xPos = xPos + 120;
}
yPos = yPos + 22;
document.getElementById("shortpopup").style.left = xPos;
document.getElementById("shortpopup").style.top = yPos;
fadeInShort(100);
}
}

In the header of HTML pages below DIV tags are inserted for support Ajax presentation.
<div class="scroll" id="popup" align="<c:out value="${align}"/>" dir="<c:out value="${dir}"/>" ></div>
<div class="shadow" id="popupshadow" align="<c:out value="${align}"/>" dir="<c:out value="${dir}"/>" ></div>

Also I need to cal Asynch routines by a simple code like this:

<input type="text"
autocomplete="off" size="30" id="target_id" name="target" onkeydown="fo(0);fadeOutShort(0);">

In the server-side a servlet like this is supporting clients requests:


package web;
Public class ProductSearchServlet extends HttpServlet {
protected final Log logger = LogFactory.getLog(getClass());
private ServletContext context;
public void init(ServletConfig config) throws ServletException {
super.init(config);
this.context = getServletContext();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
String targetId = request.getParameter("target");
if (request.getParameter("returnto") != null) {
returnTo = request.getParameter("returnto");
id = request.getParameter("id");
}
if (request.getParameter("focusto") != null) {
focusTo = request.getParameter("focusto");
}
if (request.getParameter("unit") != null) {
unit = request.getParameter("unit");
}
logger.info(" request request.getContextPath() "
+ request.getContextPath());
try {
StringBuffer str = new StringBuffer();
List list;

if (repoId.equals("")) {
logger.info(" repoId = null ");
list = prodm.getProductsLike(targetId);
} else {
logger.info(" repoId = " + repoId);
list = prodAm.getAvailableProductsAmountListLike(targetId,
Integer.parseInt(repoId));
}
Locale loc = new Locale(lang);
MessageSourceAccessor msg = new MessageSourceAccessor(ctx, loc);
if (list.size() > 0) {


str.append(" RESPONSE ");
}

}
str.append("</table>");
response.setContentType("text/html");
response.setHeader("Cache-Control", "no-cache");
response.getWriter().write(str.toString());
} else {
response.setContentType("text/html");
response.setHeader("Cache-Control", "no-cache");
response.getWriter().write("[clear]");
}
} else {
response.setContentType("text/html");
response.setHeader("Cache-Control", "no-cache");
response.getWriter().write("[clear]");

}
} catch (Exception ex) {
logger.info(" >>>>> exception : " + ex.getMessage());
}
}
}



Client side mechanisms are ready to use for any framework/style. Server side part also can be deployed by any other technologies.



To get maximum performance I prevented to use any Decorator or XML interface between Server side and Web-UI.

 
Answer #3    Answered By: Salvador Alexander     Answered On: Dec 26

Instead of using this huge code , you can use modern AJAX frameworks.
In Java/Java EE like DWR and DOJO.
You can also use modern web  frameworks like Ajax enabled JSF implemetations, struts2, GWT
and so forth.

 
Answer #4    Answered By: Andrew Bryant     Answered On: Dec 26

I agree with you. I also believe a programmer needs to know how underlying layers work. It is not enough to put components together, wire them and push the Deploy button right from the start. My impression was that Aboda wanted to "understand" how asynchronous JavaScript works. Thank you anyway for the the components and frameworks you introduced.

 
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