Skip to main content

4 Remarkable Notes for JSF Apps Using HTML5


In the previous post, I've already shared with you how my team consults clients by using a HTML prototype. This post is about the used technologies for reusing the provided HTML template and communicating with backend.

What is the issue when using HTML elements with Primefaces components?

Primefaces is a great extension for developing JSF web apps. However, it is really frustrating in case we have to make it work with an existing HTML template. Why?
- Primefaces has its own theme for styling.
- Primefaces changes the HTML structure.
Therefore, that would be a huge effort to use the Primefaces' components to replicate the elements of the HTML template; especially it is impossible for images drawing by "canvas" tag.

That requires us to find a better approach. Since Java EE 7 (introducing JSF 2.2 included), it supports to use HTML5 elements. The idea is that JSF components don't effect the style and HTML structure, so we can easily reuse the provided HTML template. Moreover, we're still able to use Primefaces "No-GUI" components such as "p:ajax", "p:remoteCommand'.

1. JSF Alternatives for HTML5 elements

We can choose to use JSF components, HTML5 elements, or both. Take a look the table "How Facelets Renders HTML5 Elements" of the following link for more detail.
https://docs.oracle.com/javaee/7/tutorial/jsf-facelets009.htm
For example:
<html ... xmlns:jsf="http://xmlns.jcp.org/jsf"
...
    <input type="email" jsf:id="email" name="email"
           value="#{reservationBean.email}" required="required"/>

2. Radio button or How to make a trick for events

There is no JSF component for radio elements. We have to build an alternative by our own. For example:
<div id="gender">
 <div class="control">
  <input type="radio" name="option" checked="true"
   onclick="document.getElementById('gender-hidden-input').setAttribute('value', '0'); onGenderChange();" value="0"></input>
  <label class="control__label" for="optionone">Option One</label>
 </div>
  
 <div class="control">
  <input type="radio" name="option" 
    onclick="document.getElementById('gender-hidden-input').setAttribute('value', '1'); onGenderChange();" value="1"></input>
  <label class="control__label" for="optiontwo">Option Two</label>
 </div>
  
 <h:inputText value="#{data.dataModel.gender}" styleClass="hidden" type="text" id="gender-hidden-input" />
 <p:remoteCommand name="onGenderChange" actionListener="#{logic.onGenderChange}" update="growl"></p:remoteCommand>
</div>

3. Dialog or How to custom Ajax requests

For dialogs/pop-ups, we can use a JQuery library like basicLightbox. We can use "p:remoteCommand" to call ajax  requests to backend. The following is an idea for passing a javascript function as param when executing from different places.
...
okElem.forEach(function (elem) {
 elem.onclick = function (e) {
  
  if(elem.classList.contains("mf-ui-disabled")){
   return false;
  }
  
  var ajaxRequestor = elem.getAttribute('data-ajax-requestor');
  if(ajaxRequestor){
   executeFunction(ajaxRequestor); //ajaxRequestor is a javascript function name which can make by "p:remoteCommand"
  }
  
  instance.close();
  e.preventDefault();
 };
});

...

function executeFunction(functionStr){
 var fn = window[functionStr];
 if (typeof fn === "function") fn();
}

4. Images Exporting

So far, html2Canvas has been the only one library can help us satisfy the requirements of exporting images from client side for all supported browsers including Chrome, Firefox and IE11. Almost other libraries for "html and canvas conversion" won't work with IE due to IE does not support SVG <foreignObject> tag. A fun fact here is this library even has not been released at the time we applied it for our project.
function exportProductChart(){
 
 var productHouse = document.querySelector("#overallPdfExportHouseWrapper");
 
 html2canvas(productHouse, {
   scale: 3,
      onrendered: function(canvas) {
       var productHouseImg = canvas.toDataURL("image/png");
       onClickExportPdfDialogOkBtn = function() {//override the function "onClickExportPdfDialogOkBtn" because this function can be called in another place.
     PrimeFaces.ab({
      s:"onClickExportPdfDialogOkBtn",
      f:"mainForm",
      p:"pdfExportDialog",
      u: "pdfExportDialog",
      onco:function(xhr,status,args){
       $('[id$=downloadPdf]').click();
      },
      pa:[{name: "mfDialogAction", value: "productChartExport"},
          {name: "productChoiceHouse", value: productHouseImg}]
     });
    }
    onClickExportPdfDialogOkBtn(); //p:remote command
    }
 });
}

References:
[1]. http://www.oracle.com/technetwork/articles/java/enterprise-html5-2227136.html
[2]. https://docs.oracle.com/javaee/7/tutorial/jsf-facelets009.htm
[3]. https://github.com/tsayen/dom-to-image

Comments

  1. Chào anh Hương, em là sinh viên mới tiếp cận Java và CNTT nên không biết nhiều. Em đang định dùng lại code mã nguồn mở của SweetHome 3D nhưng mò mẫm mãi vẫn không xem được code của họ. Mong anh chỉ giáo

    ReplyDelete
    Replies
    1. Chào bạn!
      Tôi chưa có kinh nghiệm lập trình với SweeHome 3D, nên tôi sẽ chỉ có thể cho lời khuyên:
      1. Bạn nên làm theo hướng dẫn này Developer Guide. (phải cái bạn nỏi không??)
      2. Bạn xem source code của file jar (Download) bằng java decompiler (vd: JD) hoặc cài plugin decompiler trên Eclipse.

      Không biết bạn đã tham gia cộng đồng này Dạy Nhau Học chưa, nếu chưa thì bạn có thể lên đây đặt câu hỏi và chia sẻ lại với mọi người.

      Delete

Post a Comment

Popular posts from this blog

Coding Exercise, Episode 1

I have received the following exercise from an interviewer, he didn't give the name of the problem. Honestly, I have no idea how to solve this problem even I have tried to read it three times before. Since I used to be a person who always tells myself "I am not the one good at algorithms", but giving up something too soon which I feel that I didn't spend enough effort to overcome is not my way. Then, I have sticked on it for 24 hours. According to the given image on the problem, I tried to get more clues by searching. Thanks to Google, I found a similar problem on Hackerrank (attached link below). My target here was trying my best to just understand the problem and was trying to solve it accordingly by the Editorial on Hackerrank. Due to this circumstance, it turns me to love solving algorithms from now on (laugh). Check it out! Problem You are given a very organized square of size N (1-based index) and a list of S commands The i th command will follow t...

Make simple music program with beep(freq, duration) with Pascal

Pascal is my first programing language when I have studied in high school. It was really exciting for me. :) The Pascal programming language was created by Niklaus Wirth in 1970. It was named after Blaise Pascal, a famous French Mathematician. It was made as a language to teach programming and to be reliable and efficient. Pascal has since become more than just an academic language and is now used commercially . I tried to make a simple music program by using Lazarus IDE on MS Window 7, 64-bit. It frustrated me a few times how difficulty to use Sound command to make a sound. Sound did not work on my compiler and my platform anymore. So far, I just could use beep(freq, duration) from window unit to implement my work. Here is my code. ;) program mysong; uses Windows, crt; const C: Integer = 512; { x = A * EXP(LN(2)/12)} C_: Integer = 542; D: Integer = 574; D_: Integer = 608; E: Integer = 644; F: Integer = 682; F_: Integer = 723; G: Integer = ...

[Snippet] CSS - Child element overlap parent

I searched from somewhere and found that a lot of people says a basic concept for implementing this feature looks like below: HTML code: <div id="parent">  <div id="child">  </div> </div> And, CSS: #parent{   position: relative;   overflow:hidden; } #child{   position: absolute;   top: -1;   right: -1px; } However, I had a lot of grand-parents in my case and the above code didn't work. Therefore, I needed an alternative. I presumed that my app uses Boostrap and AngularJs, maybe some CSS from them affects mine. I didn't know exactly the problem, but I believed when all CSS is loaded into my browser, I could completely handle it. www.tom-collinson.com I tried to create an example to investigated this problem by Fiddle . Accidentally, I just changed: position: parent; to position: static; for one of parents -> the problem is solved. Look at my code: <div class="modal-body dn-placeholder-parent-positi...

Generating PDF/A From HTML in Meteor

My live-chat app was a folk of project Rocket.Chat which was built with Meteor. The app had a feature that administrative users were able to export the conversations into PDF files. And, they wanted to archive these files for a long time. I happened to know that PDF/A documents were good for this purpose. It was really frustrated to find a solution with free libraries. Actually, it took me more than two weeks to find a possible approach. TL, DR; Using Puppeteer to generate a normal PDF and using PDFBox to load and converting the generated PDF into PDF/A compliance. What is PDF/A? Here is a definition from Wikipedia: PDF/A  is an  ISO -standardized version of the  Portable Document Format  (PDF) specialized for use in the  archiving  and long-term  preservation  of  electronic documents . PDF/A differs from PDF by prohibiting features unsuitable for long-term archiving, such as  font  linking (as opposed to  font em...

The power of acceptance test

User Story is the place PO gives his ideas about features so that developers are able to know what requirements are. Acceptance tests are these show the most valuable things of the features represented by some specific cases. Usually PO defines them, but not always. Therefore, refining existing acceptance tests – even defining new ones that cover all features of the User Story must be a worth task. Acceptance test with Given When Then pattern If we understand what we are going to do, we can complete it by 50% I have worked with some members those just start implementing the features one by one and from top to down of the User Story description. Be honest, I am the one used to be. What a risky approach! Because it might meet a case that is very easy to miss requirements or needs to re-work after finding any misunderstood things. I have also worked with some members those accept spending a long time to clarify the User Story. Reading carefully of whole User Story by defining...