Develop Reference

Struts 1 - Calling more actions via one post without altering struts-config

I'm working on a legacy app (struts 1, own framework, java 6, on WebSphere 7) where I need to change the behavior of an operation.
Let's call them (1) CopyItem, (2) AlterItem, (3) MarkAsCopied.
A button called one service which needs to be replaced with three other services.
Depending on the result of the first one, invoke the second one and so on.
I want to navigate in the end where the first one would take me (so it would look like the original behavior from user point of view).
Initially I thought I wrap every parameter I need into a form, POST it, and then on the Java side, I would call action execute for each service. Technically from CopyItemAction.execute() of CopyItem I would call AlterItem and MarkAsCopied executes as well.
I feel that this is pretty far from a clean solution.
Do you have a better idea, how to do this?

In the end I did it via synchronized Ajax. Which is definitely bad practice, so I do not recommend if you have the access on the backend code. However in my case now it turned out to be a working not-that-ugly solution. Based on Dave Newton's (https://stackoverflow.com/users/438992/dave-newton) proposal.
Keep that in mind the struts actions are still called according to the configuration defined in struts-config.xml.
I created the js function below and invoked the services with the specified forms one by one. This way a form (POST) submit calls the struts action, but doesn't navigate away. After they run successfully I redirected the page.
function submitForm(form) {
if (form !== null && form !== undefined) {
let formData = new FormData(form);
let xhr = new XMLHttpRequest();
xhr.open('POST', form.getAttribute('action'), false);
var successResponse = false;
xhr.onreadystatechange = function() {
if(xhr.readyState == XMLHttpRequest.DONE) {
successResponse = xhr.status == 200;
}
}
xhr.send(formData);
return successResponse;
}
}
In conclusion: this is not a recommended solution, but if you're in such a situation like me, then it works.

How to pass javascript variable in jsp page to another java file?

Good Evening, I try to do a checkbox which embedded in a JSP page. I use document.getElementByID("checkbox") in the JSP javascript function. How to pass the variables in the javascript function to another java file without passing it through url for security concern?
This is Checkbox Function:
var checkbox = document.getElementById("chbx");
function foo(){
if(checkbox.checked=true){
//passThisVariableToAnotherJavaFile-isChecked
}
else {
//passThisVariableToAnotherJavaFile-isNotChecked
}
};
This is Java File:
public class CheckBoxEvent{
if(isChecked) {
//then whatever
} else if (isNotChecked) {
//then no whatever
}
}
I am a newbie is this jsp stuff, I used to be doing this in PHP but everything mixed-up in my mind when there is a HashMap appear in the java file. Well, need some hints and help.
Thank You

How to pass the variables in the javascript function to another java file without passing it through url for security concern?
You have two options here and in both the cases you need to send the value to the server for processing :
An AJAX POST or GET request. This looks more appropriate to your requirement. You can get an example here.
Submit the form using POST.
Read here When do you use POST and when do you use GET?
In both the cases , there will be a Servlet/JSP/Controller handling the request in the server. You can call the methods in your Custom Java class with the request parameters.

when you do var checkbox = document.getElementById("chbx"); you are doing it at client side. Now if you want to propagate this value to server side i.e to some java class(most of the cases it will be servlets) then you have two options:-
1)Make an AJAX call. (You can also use jquery here to make AJAX call).Here is
the small example, you can find ample on google
$.ajax({
type: 'GET',
dataType: 'json',
url: servlerURL,
success: function(reply) {
},
error: function (xhr, textStatus, errorThrown) {
}
});
or
2)Submit the form

Ruby on Rails, How to Update Div with Ajax on like/unlike

So the problem I am having is getting my like/unlike button to refresh with ajax in my Ruby on Rails app, here is my code:
app/views/_comment.html.haml
- likes = comment.likes
%div.comment{id: "comment-#{comment.id}"}
.comment-avatar
.medium-user-avatar.avatar-canvas
- if comment.user.avatar_url
= image_tag comment.user.avatar_url(:medium)
- else
%span.medium-user-initials.initials-decoration
= comment.user.avatar_initials
%span.comment-username= link_to(comment.user_name, "#")
%span.comment-body~ markdown(comment.body)
.comment-time
= time_ago_in_words(comment.created_at) + " ago"
- if can? :like, comment
= " · "
- if likes.find_by_user_id(current_user.id).nil?
= link_to "Like", like_comment_path(comment), method: :post, remote: true
- else
= link_to "Unlike", unlike_comment_path(comment), method: :post, remote: true
- if comment.user == current_user
= " · "
= link_to "Delete", comment_path(comment), method: :delete, remote: true,
:data => { :confirm => "Are you sure you want to delete this comment?" }
- if likes.count > 0
.comment-likes
- likers = likes.map { |like| link_to(like.user_name, "#") }
- if likers.length > 1
- likers = likers.slice(0, likers.length - 1).join(", ").concat(" and " + likers.slice(-1))
- else
- likers = likers[0]
= "Liked by #{likers}".html_safe
app/controllers/comments_controller.rb
class CommentsController < BaseController
load_and_authorize_resource
def destroy
destroy!{ discussion_url(resource.discussion ) }
end
def like
comment_vote = resource.like current_user
Event.comment_liked!(comment_vote)
#redirect_to discussion_url(resource.discussion )
render :partial => "like"
comment_likes
end
def unlike
resource.unlike current_user
#redirect_to discussion_url(resource.discussion)
render :partial => "unlike"
comment_likes
end
def comment_likes
render :partial => "comment_likes"
end
end
and then the .js.erb files for like, unlike and comment_likes:
app/views/_like.js.erb
$(".comment-time a#like").html("<%= escape_javascript(render('.comment-time a#like'")
app/views/_unlike.js.erb
$(".comment-time a#unlike").html("<%= escape_javascript(render('.comment-time a#unlike'")
app/views/_comment_likes.js.erb
$(".comment-likes a##").html("<%= escape_javascript(render('.comment-likes a##'")
Currently clicking like will update the database but will not show the changes until a page refresh, I just want to refresh the individual div's with ajax. A little more information about the div's could help so the ruby creates the html and contained in that as an example is or when already liked I just need to refresh these divs to show the latest from the database aswell as which contains http://localhost:3000/comments/7/unlike 500 (Internal Server Error)"
The rest of the scripting has been done in coffeescript if that matters? I read that the controller functions should use .js.erb so hope this isn't affecting it all. (Im sure my js.erb's are wrong)

I'm not sure if this is the main problem but one thing to fix would be the render statement in your .js.erb files.
The Rails render method requires as its argument the erb template or action to render. When you call:
render('.comment-time a#unlike')
Rails will try to find a template with the name ".comment-time a#unlike" somewhere in your view path which will probably raise some kind of error. Make sure you pay attention to the difference between what's happening in your javascript (in the client) in your application (on the server.)
So one way to fix this would be as follows. First check what part of the view you want to update, for simplicity's sake because you already have the _comment partial let's use that. Second figure out which part in the dom it should replace, in your case the div with the current comment's ID. We can then do the following:
$("#comment-<%= #comment.id %>").replace_html(
"<%= escape_javascript render('comments/comment', :comment => #comment) %>"
);
This will render the _comment.html.erb partial in app/views/comments, insert the result (escaped) into the javascript in your (dis-)like.js.erb and send that back to the browser to execute. The browser will then replace_html on the comment's div (indicated by the ID.)
Because we're replacing the whole comment div you can use the same method for both like and dislike. If you need to save bandwidth you could fine tune it to only re-render the like button itself, but for now this will work.

The problem is your Controller does not know how to respond to the ajax request. By default the render method will render html.erb or in your case html.haml templates.
Unless you do something like:
respond_to do |format|
format.js { comment_likes }
end
Now if an ajax requests comes in the _comments_likes.js.erb template will be rendered.
If you have more of these ajaxy type questions there are efforts being put into rewriting the ajax guides for rails.
And by the by, please consider cleaning up your view.

Can you capture end user's Java version when they run an applet?

An applet developed outside our company just started failing for some users this week. Apparently it was because of the latest version of java (1.6u24) that auto updated. Is there a way to capture what version of java the user opened the applet with?

You can use System.getProperty("java.version") to get that information. This is an example applet that uses it and the About page has the source.

You can use System.getProperty, specifically :
System.getProperty("java.version")
For a list of possible key value, see : getProperties()

http://pscode.org/prop/?prop=java.version%2Cjava.vm.version

Using the answers from another question, I ended up writing the code below. When the page loads, I get the user's java version then use an ajax call to save it where ever I need to. The part I used was the reference to the deployJava.js from Sun.
$(document).ready(function() {
var jVersion = "";
for (var i = 0; i < deployJava.getJREs().length; ++i) {
jVersion += deployJava.getJREs()[i];
}
var url = 'saveJavaVersionAction.jsp';
var params = 'version=' + jVersion;
$.ajax({
url: url,
data: params,
success: function(html) {
$("#results").append(html);
}
});
});

Saving a web page as image

As a hobby project I am exploring the ways to save a web page (HTML) as image, mostly programatically using c/c++/javascript/java. Till now I have come across the following ways:
Get the IHTMLElement of page body and use it to query for IHTMLElementRender and then use its DrawToDC method (Ref: http://www.codeproject.com/KB/IP/htmlimagecapture.aspx ). But the problem is that it did not work for all the pages (mostly pages having embedded iframes).
Another way which i can think of is to use some web browser component and when the pages is fully loaded then capture it using BitBlt (Ref: http://msdn.microsoft.com/en-us/library/dd183370%28VS.85%29.aspx ). But the problem is that the page I have requested may be longer than my screen size and it will not fit into the web browser component.
Any direction/suggestion to resolve above issues or an alternative approach is greatly appreciated.

If you use Python, there's pywebshot and webkit2png. Both of them have some dependencies, though.
Edit: Oops, Python is not in your list of preferred languages. I'll leave this answer here anyway, because you said "mostly" and not "exclusively".

Another (somewhat roundabout) option would be to run a server like Tomcat and use Java to call a command-line tool to take a screenshot. Googling for "command line screenshot windows" comes up with some reasonable-looking possibilities. Besides running a server, though, I don't know a good way to run local executables from javascript. This method would make it cross-browser, though, which is a plus (just make an ajax call to the script when you want a screenshot).
Unfortunately I don't actually know how to deploy war files. It might be more trouble to use Tomcat; I mentioned it because Java was a preferred language. It would be fairly simple to run XAMPP and use this PHP snippet, and you wouldn't really have to learn php:
<?php
exec("/path/to/exec args");
?>
EDIT
You know, I'm not sure that really answers your question. It's one way, but it's coming at it from the JavaScript end rather than the scripting end. If you want to do it via scripting, you could always use Selenium. It supports capturing screenshots of an entire page, and can be controlled via Java.

Well finally able to crack it by going through these two articles:
http://www.codeproject.com/KB/GDI-plus/WebPageSnapshot.aspx [c# code - IE]
http://www.codeproject.com/KB/graphics/IECapture.aspx [c++ & GDI - IE]
Can't share the code, but the above two articles will give you the best possible solution.
Also have a look at:
https://addons.mozilla.org/en-US/firefox/addon/3408/ [firefox + javascript]
Above things are still ok. BUT not guaranteed to work always. Check the below link:
How do I render the scrollable regions of a canvas with IViewObject::Draw?

If you are OK using javascript for it, I suggest going with phantomjs
Example from http://fcargoet.evolix.net/
var page = new WebPage(),
address = 'http://dev.sencha.com/deploy/ext-4.0.7-gpl/examples/feed-viewer/feed-viewer.html';
page.viewportSize = {
width : 800,
height : 600
};
// define the components we want to capture
var components = [{
output : 'feed-viewer-left.png',
//ExtJS has a nice component query engine
selector : 'feedpanel'
},{
output : 'feed-viewer-preview-btn.png',
selector : 'feeddetail > feedgrid > toolbar > cycle'
},{
output : 'feed-viewer-collapsed.png',
//executed before the rendering
before : function(){
var panel = Ext.ComponentQuery.query('feedpanel')[0];
panel.animCollapse = false; // cancel animation, no need to wait before capture
panel.collapse();
},
selector : 'viewport'
}];
page.open(address, function (status) {
if (status !== 'success') {
console.log('Unable to load the address!');
} else {
/*
* give some time to ExtJS to
* - render the application
* - load asynchronous data
*/
window.setTimeout(function () {
components.forEach(function(component){
//execute the before function
component.before && page.evaluate(component.before);
// get the rectangular area to capture
/*
* page.evaluate() is sandboxed
* so that 'component' is not defined.
*
* It should be possible to pass variables in phantomjs 1.5
* but for now, workaround!
*/
eval('function workaround(){ window.componentSelector = "' + component.selector + '";}')
page.evaluate(workaround);
var rect = page.evaluate(function(){
// find the component
var comp = Ext.ComponentQuery.query(window.componentSelector)[0];
// get its bounding box
var box = comp.el.getBox();
// box is {x, y, width, height}
// we want {top, left, width, height}
box.top = box.y;
box.left = box.x;
return box;
});
page.clipRect = rect;
page.render(component.output);
});
// job done, exit
phantom.exit();
}, 2000);
}
});