I'm currently developing a Java project where I need to implement a Webserver. The webserver should be implemented because the installation should be easy. I already took a look at WebServlet and HttpServer from sun. As far as I know, it is always necessary to put the whole html into quotes in oder to use vars -e.g. collecting data from DB. What is the easiest way to use java code in html like php? (not js) Including the php module into the java server seems wrong to me. But when putting the whole document into vars, quotes are always necessary and it has no syntax highlights.
EDIT: I do not mean static content :)
I've been having terrible luck trying to get this to work, so I'm hopeful someone can help here.
In Java, I need to be able to take an HTML page with JavaScript within it and detect any JavaScript errors without, preferably without executing the JavaScript code.
I found this article:
Javascript parser for Java
And I've attempted to figure out how I'm supposed to use Caja to do this, but I'm having a difficult time finding any documentation with working examples of anything close to what I'm doing.
As a result I took a look at Nashorn also referenced in that article. I found a few examples which show how to execute JavaScript code from Java, but this doesn't process the whole HTML page. Even then, the execution doesn't seem to include the ability to validate common JavaScript functions (e.g. It hadn't heard of "alert").
Can anyone recommend something that might be able to do what I want, and point me in the right direction for their documentation or give me an example?
jshint as a standalone product seems to be a good fit for this:
it can run in java inside rhino (see https://github.com/jshint/jshint/)
a nodejs package exists (see https://www.npmjs.com/package/jshint)
it works with nashorn but it's quite tricky
I will only cover the technical difficulties around 3rd solution as I finally managed to make it work too...
Spoiler alert: "alert()" is not detected yet... Solution nb 2 will help there...
You first need to grab this specific release of jshint: https://github.com/jshint/jshint/releases/tag/2.4.4
Anything later than v2.7.0 will fail for now and I personally gave up patching intensively prototypes and namespaces... Releases from v2.4.4 until v2.6.3 work without modification but are limited in functionalities.
In the release notes, it's specifically written that "support for the Nashorn JavaScript engine" is working on this release. I'm using JDK8 nashorn 1.8.0_45 for this test.
Next step is to extract from this release this single file jshint-2.4.4/dist/jshint-rhino.js
Now you need to run nashorn/jjs in scripting mode and you need to be specific about the single file you wish to verify. In solution 2 (nodejs based) you can do multiple files or a complete hierarchy below a folder...
Create a simple file file.js:
function(){}
Now run the following command (please note the presence of -- ):
jjs -scripting jshint-rhino.js -- file.js
This will give you the following output:
Missing name in function declaration. (file.js:1:9)
> function(){}
So this covers the how to run jshint in a simple manner with nashorn... With the 3rd solution, at least you can find missing semicolons and several typical errors. But it's not a silver bullet and to me it's not a real alternative.
My personal preference would be to stick to solution 2 only. If you've the possibility to install either nodejs or iojs on your dev platform, go and grab https://www.npmjs.com/package/jshint. Not only will you be able to do more than the 3rd solution, you'll also be able to configure a jshintrc file as described at http://jshint.com/docs/
I use embedded jetty, osgi in my web project.
I want to change the code in freemarker files in the web project at runtime. What is the best way to realize it?
Best regards.
Assuming the templates will be replaced under the control of the Web application, when you know a template has been replaced, you could call Configuration.removeTemplateFromCache on it, so that it will be guaranteed that the next Configuration.getTemplate will return the new file. This also means that you don't have to set a low template_update_delay on the production server.
The more tricky question is if FreeMarker can accidentally see a partially replaced or exclusively locked (can't open it) file while you are replacing it. During development you don't care because it has near 0 chance, but on a production server you do. This is up to the TemplateLoader implementation, and then the storage behind it. Like if it's DB-backed, there's certainly no such risk. For File-s, I guess there can be such glitches. Unfortunately, you can't force FreeMarker to keep a template in the template-cache while you are replacing it. But you can achieve something very similar on the TemplateLoader-level instead. You could create a custom TemplateLoader to which you can tell something like myTemplateLoader.mirrorToMemory(fileName), then you replace the file, then you call myTemplateLoader.releaseMirrorOf(fileName). And then you invalidate the template-cache entry as I said earlier.
I'm about to choose to way to organize my view (with spring-mvc, but that shouldn't matter much)
There are 6 options as far as I see (though they are not mutually exclusive):
Tiles
Sitemesh
Freemarker
Velocity
<jsp:include>
<%# include file="..">
Tiles and Sitemesh can be grouped; so can Freemarker and Velocity. Which one within each group to use is not a matter of this discussion, there are enough questions and discussions about it.
This is an interesting read, but can't quite convince me to use tiles.
My question is - what do these frameworks give that can't be properly done with <# include file=".."> and JSTL. Main points (some taken from the article):
Including parts of pages, like header and footer - there isn't a difference between:
<%# include file="header.jsp" %>
and
<tiles:insert page="header.jsp" />
Defining parameters in the header - like title, meta tags, etc. This is very important, especially from SEO point of view. With the templating options you can simply define a placeholder which each page should define. But so you can in jsp with JSTL, using <c:set> (in the including page) and <c:out> (in the included page)
Layout reorganization - if you want to move the breadcrumb above the menu, or the login box above another side-panel. If page inclusions (with jsp) is not well organized, you might need to change every single page in such cases. But if your layout is not overly complex, and you put the common things in header/footer, there is nothing to worry about.
Coupling between the common components and the specific content - I don't find an issue with this. If you want to reuse some fragment, move it to a page that doesn't include any header/footer, and include it wherever needed.
Efficiency - <%# include file="file.jsp" %> is more efficient than anything else, because it is compiled once. All other options are parsed/executed many times.
Complexity - all non-jsp solutions require additional xml files, additional includes, pre-processor configurations, etc. This is both a learning curve and introducing more potential points of failure. Also, it makes support and changing more tedious - you have to check a number of files/configurations in order to understand what's happening.
Placeholders - do velocity/freemarker give anything more than JSTL? In JSTL you put placeholder, and use the model (placed in request or session scope, by controllers) to fill these placeholders.
So, convince me that I should use any of the above frameworks instead of/in addition to plain JSP.
A few arguments for Velocity (I haven't used Freemarker):
Potential to re-use templates outside of a web context, such as in sending emails
Velocity's template language syntax is far simpler than JSP EL or tag libraries
Strict separation of view logic from any other sort of logic - no possible option to drop down to using scriptlet tags and doing nasty things in your templates.
Placeholders - do velocity/freemaker give anything more than JSTL? In JSTL you put placeholder, and use the model (placed in request or session scope, by controllers) to fill these placeholders.
Yes, references are really the core of VTL:
<b>Hello $username!</b>
or
#if($listFromModel.size() > 1)
You have many entries!
#end
Efficiency - <%# include file="file.jsp" %> is more efficient than anything else, because it is compiled once. All other options are parsed/executed many times.
Not so sure I agree with or understand this point. Velocity has an option to cache templates, meaning the abstract syntax tree they are parsed into will be cached rather than read from disk each time. Either way (and I don't have solid numbers for this), Velocity has always just felt fast for me.
Layout reorganization - if you want to move the breadcrumb above the menu, or the login box above another side-panel. If page inclusions (with jsp) is not well organized, you might need to change every single page in such cases. But if your layout is not overly complex, and you put the common things in header/footer, there is nothing to worry about.
The difference is, with a JSP approach, wouldn't you be re-organzing this layout in every JSP file that uses the same header/footer? Tiles and SiteMesh allow you to specify a base layout page (JSP, Velocity template, etc - both are JSP frameworks at their heart) where you can specify whatever you want and then just delegate to a "content" fragment/template for the main content. This means there would be just one file to move the header in.
The choice between jsp:include and Tiles/Sitemesh/etc is the choice between simplicity and power that developers face all the time. Sure, if you only have a few files or don't expect your layout to change very often, then just use jstl and jsp:include.
But applications have a way of growing incrementally, and it can be hard to justify the "stop new development and retrofit tiles (or some other solution) so we can fix future problems more easily", which is required if you don't use a complex solution in at the start.
If your sure your application will always remain simple, or you can set some benchmark of application complexity after which you will integrate one of the more complex solutions, then I'd recommend not using tiles/etc. Otherwise, use it from the get-go.
I'm not going to convince you to use other technologies. For all I know everyone should just stick to JSP if it works for them.
I work mainly with Spring MVC and I find JSP 2+ in combination with SiteMesh the perfect match.
SiteMesh 2/3
Provide decorators to be applied to the views mostly like inheritance works in other templating engines. Such feature is unthinkable to work without nowadays.
JSP 2+
People claiming that JSP will make it hard to avoid Java code in templates is bogus. You just shouldn't do it and with this version it's unnecessary to do so. Version 2 supports calling methods using EL which is a big advantage compared to previous versions.
With JSTL tags your code will still look like HTML so it's less awkward. Spring packs a lot of support for JSP through taglibs which is very powerful.
The taglibs are also easy to extend so customizing your own environment is a breeze.
One of the best arguments for facelets (not in your list, but I'll just mention it) opposed to using JSP is that the compilation is integrated with the interpreter instead of being delegated to the JSP compiler. This means that one of the most annoying things I had with JSF 1.1 - having to change the id-attribute on a surrounding JSF-tag when saving a change in order for the runtime engine to discover the change - went away, giving the save-in-editor, reload-in-browser cycle back, along with much better error messages.
A good view technology eliminates most and most anoying if/switch/conditional statements, simple include does not. Using a 'complex' view technology results in a 'simple' application.
You didn't provide information about specific of your applications. For example I do not use JSP just for few reasons:
It is hard to avoid using Java code in JSP templates so your break concept of pure View, and as result you will have difficulties to maintain code in several places as view and controller
JSP automatically creates JSP context which establishes a session. I may want to avoid it, however if your applications always use session it can be not a problem for you
JSP requires compilation and if target system doesn't have Java compiler, any minor tweaking will require to use other system and then redeploy
Minimal JSP engine is about 500k of bytecode plus JSTL, so it can be not suitable for embedded systems
Template engine can generate different content type of the same model, let say JSON payload, webpage, e-mail body, CSV and so on.
Non Java programmer may have difficulties to work with JSP templates, when non technical people never had difficulties to modify regular templates.
I was asking same question long time ago and ended by writing my framework (surely template engine based) which was free from all disadvantages I saw in other solutions. Needless to say it is about 100k of byte code.
I realize that this comes off as a smart ass answer, but the truth of it is, if you don't see any advantage to using templating over code in your current project, it's probably because in your current project, there isn't one.
Part of it is about scale. You might think that includes are every bit as powerful as let's say sitemesh, and that's certainly true, at least for a small number of pages (I'd say probably about 100), but if you have several thousands it starts becoming unmanageable. (So for eBay it's not necessary, for Salesforce it probably is)
Also, as has been mentioned before, freemarker and velocity are not servlet specific. you can use them for anything (mail templates, offline documentation, etc.). You do not need a Servlet container to use freemarker or velocity.
Lastly your point 5 is only partially true. It is compiled every time it is accessed if it has not been so already. This mean that whenever you change something you need to remember to delete your servlet containers "work" directory, so that it recompiles the JSP. This is unnecessary with a templating engine.
TL;DR Templaing engines were written to address some (perceived or real) shortcomings of JSP + JSTL. Whether you should use them or not depends entirely on your requirements and the scale of your project.
I've never used Java before (C# is my domain), but now I have a task that I must apply a specific style to for a tiny Java webpage. The style is from another ASP.NET application that we're rolling out and that I've helped to develop. Seems that this style is on the way to become our new company web-style. :P
The webpage is really tiny - it has only a login form and an action form with a dozen textboxes and a button. When you click the button, a file is generated and available for download.
This application has already been made by a colleague of mine, who has good experience with Java, but nearly no experience with the web. So he's no help anymore. For now the application has NO style at all. Just a bunch of textboxes.
The application is made in NetBeans and Java Faces - as far as I understand. Or maybe it's "Visual Faces". Not sure - can't make heads or tails with all these names from the Java world. Anyway, it's this ASP.NET look-alike where you have an XML page with tags like <ui:textField> and <ui:passwordField>, and then a code-behind file with all your Java code. (Actually I suspect that ASP.NET was created after this, but that's besides the point)
I've successfully converted the HTML layout to the one I need and set my own CSS/JavaScript files in the header. There's just one problem - the Faces thing is hell-bent on including its own CSS stylesheets as well. Sounds reasonable of course, but for some mind-boggling reason these stylesheets also deem it necessary to override styles on all the common tags - <body>, <div>, <span>, etc. Which is annoying, because that breaks my design. Now, I could change my own stylesheets to over-override these default Faces stylesheets, but that seems... well, not the right solution. It's like a workaround, not a "correct" solution. Why should I redefine font attributes for every tag, when it should easily cascade down from the "body" tag?
Is there any way how I can tell Faces not to include its own stylesheets? I won't be using any of their controls anyway - just textboxes and buttons. And labels, when I find them. :P
Oh, yes, and I tried to re-create it all in simple JSP (no Faces), but that failed, because the code-behind (there's some big library there) is dependent on it... This is also the reason why I can't move it to the ASP.NET I'm so familiar with.
Added: Since it seems there are many Java Faces frameworks out there, here's a snippet of code that might help:
<jsp:root version="1.2" xmlns:f="http://java.sun.com/jsf/core" xmlns:h="http://java.sun.com/jsf/html" xmlns:jsp="http://java.sun.com/JSP/Page" xmlns:ui="http://www.sun.com/web/ui">
<jsp:directive.page contentType="text/html;charset=UTF-8" pageEncoding="UTF-8"/>
<f:view>
<ui:page id="page1">
<ui:html id="html1">
<ui:head id="head1">
Also I forgot to mention that there is a folder in NetBeans called "Sun Web UI Components Themes" which has three items under it - "Gray Theme", "Green Theme" and "Default Theme". I can choose one of them as the active one, and that also changes the CSS which is included by default. Unfortunately I cannot choose none.
OK, I already changed my style to override these stylesheets. Still it would be nice to hear more about what I'm dealing here with. I don't even know where I should look for documentation...
Added 2: Also, the namespace for say, TextField, is com.sun.rave.web.ui.component.
Which JSF (JavaServer Faces) library is this using? MyFaces? RichFaces? Something different?
I don't know if you've found this resource yet: JSF Tag lib.
If it's using <ui: type tags, then it's also using Facelets which is a templating system for JSF. However the tag parameter you are probably looking for is styleClass and Style.
There really isn't a default styling for standard JSF, and I think there's probably another JSF library that's being used. Under the WEB-INF directory is probably a directory called lib where the jar files are. Those should give you a clue as to what library's are being used.
RichFaces comes with its own styling, and is completely themeable. In your particular case, it's going to be more of a pain than it's worth for your situation. Other JSF library's may do the same.
Unfortunately I can only point you at places and ideas of where the problem might be. Given the vast number of choices when it comes to JSF, it's the best thing I can do.