I am attempting to learn Java EE. After struggling through trying to understand the Java stack, it appears that that a basic dynamic web application can be accomplished by focusing on JSP and Servlets so I want to start there.
In Net Beans I have a basic project set up with a tomcat server and when I hit run I can get the web page to generate and display the default index.jsp page. I have added a css file to the project and this jsp page looks like any standard html page now. I then create a new servlet. I was also able to create a link in the index.jsp page so when I click on it, it calls the servlet.
What I don't understand is why when I create the servlet in Net Beans, the processRequest method comes pre-populated with several html print statements. I could easily make this page look like the jsp page I started with, making me wonder why I even need a JSP page. It appears the entire application could be comprised of servlets.
Could someone please explain the proper interaction between the two? It appears the index page can contain links that call various servlets, perhaps to access a database of comments, then do I create the response table in the servlet, or would I pass that information to another JSP page?
Understanding these basic workflows would really help. Thanks
JSP also a kind of a servlet . Right after you run the jsp , go to your netbeans project directory and right click the jsp and select view Servlet then you get the servlet representation of your jsp file. Actually jsp file is there to perform front end design easily. Without jsp It is really difficult task to perform front-end developing stuff inside servlet.
And you should keep in mind there is no such a thing called proccessRequest in javaEE . It is automatically generated by Netbeans once you create a new servlet. So just stick to basics. Erase all the auto-generated stuff from the class which has extended HttpServlet. And then you can override the required HTTP method/methods. (doGet , doPost etc..) You should take a look at this for more infromation ...
And this page will also improve your knowledge on javaEE
Related
I'm new to web development with Java, so please excuse me if I'm butchering the terminology:
I'm building a web app with JSPs/servlets using the Java MVC model. I'm including a register/login option on the top menu that will of course need to communicate with the server (handle registering/logging in or retreiving the user's name).
I want to reuse both the JSP and controller code for the top menu as it should be on every page. I'm able to reuse the menu page using <c:import>. However, the menu will appear on pages that have their own functionality and therefore their own controllers. I can't figure out how to reuse the controller code for the menu on these pages as I can only map one servlet to a URL.
I don't have much code to show as an example at this point. What's the best practice for reusing common functionality like this without interfering with page specific functionality?
Not sure if I understand the problem correctly.
What about passing a hidden field in your form(which, from my understanding would point to the same mapping in your controller) specifying which jsp the request is coming from ? That way you know which jsp to call back from your controller.
Q1: Does Spring or any opensource java UI framework support partial views like that in asp.net mvc?
For example in my main index.html (or _layout.cshtm per asp.net mvc3 spec)
I would have the folllowing code:
<span id="logindisplay">#Html.Partial("_LogOnPartial")</span>
where #Html is a helper to display a partial view for _LogonPartial.cshtml which just injected it's html view contents into the page?
Q2: If this is supposed If I want to display a bunch of partial views it would be helpful to display them concurrently in parallel to improve performance. Very similar to what linkedin is doing using dust and fizzy? http://engineering.linkedin.com/profile/engineering-new-linkedin-profile
Q3: Is fizzy available as open source like that of dust?
If you want to include content of a page into another page, by adding some code on the page itself, you should compare asp with jsp, not ASP.NET MVC* with JEE - Spring MVC
So, an equivalent to <span id="logindisplay">#Html.Partial("_LogOnPartial")</span> on a jsp would be one / all of the following
On your jsp, include content from another jsp using <%# include file="../includes/inner-content.jsp" %>. This is what is called a static include. The source of the included jsp is included and made part of the parent jsp, before the jsp is compiled. If you use an IDE, it will check to ensure the included jsp does infact exist at the path specified, relative to the location of the jsp in which you are adding the include. Technically this is a JSP Directive. The jsp being included could just be a fragment, and not addressable from the outside world (could be hidden inside WEB-INF)
You can also use what's called a Dynamic include <jsp:include page="someJSP.jsp" />. In this case, the included JSP should be addressable from the browser and should be capable of being rendered independently. When the server is executing the servlet to render the parent JSP, it stops when this tag is seen, and starts executing the servlet for the included jsp, the output obtained from the inner jsp execution is then merged to the output of the parent jsp, and processing of the parent jsp is resumed.
A third option would be to use Core JSTL taglib's <c:import url=""/>. This works just like option 2 above, except it also allows you to import a page / content from a url that lives outside your application. Basically you can mention a path to a jsp, or relative URI to a servlet mapping in your application, or a URL to an external page.
Now, I suspect this is not really what you want to do, if you are comparing with what Linkedin is doing. You want to mashup content from sources in your own application, and compose your page. You also want to do this in an asynch manner so as to keep load times in check. In this case, you HAVE to use JavaScript and Ajax. All the mechanisms described above are for server rendered pages (All HTML is created before the page is rendered in the browser). Just like #HTML. You need to create a simple framework / use an existing one, where once a page loads, it fires asynch ajax calls to the server to get content for specific areas on the page and renders the returned HTML in those specific areas.
Hope this helps.
Do let me know if I've misunderstood your question.
I have a question about Java servlets convention. In looking at any tutorial for servlets, whether it be Eclipse, NetBeans, etc., they always have you create an index.jsp page. Once the page is created, they have you create a form with a "submit" button that jumps you to the servlet for processing. My question is, in a servlets project, do you have to use the main index.jsp page, or can your project go immediately to the servlet?
I am working on my own little project to learn servlets, a project that connects to my local MySQL database, displays the list of schemas you can choose from, then displays the table data for each schema on the next page. In order to dynamically grab a list of schemas on the main page, I will need a servlet, not an index.jsp page. I know this can be done with JSP or JSF, but I would like to use servlets only.
This is where my original question comes in. Can my project go to an initial main servlet instead of an index.jsp page, or does convention, or technical matters, prohibit this?
Thank you for taking the time to read. Have a good day.
Not exactly needed.you can direclty call a servlet.There is no harm in that.
like
<welcome-file-list>
<welcome-file>/index</welcome-file>
</welcome-file-list>
I recently developed a whole system in Java that connected to a database and exports and imports the table content to an excel sheet. I used SWING for the user interface. the user will interact with it for authentication and file management.
Apparently the client changed the requirements, He wants everything from a Web Interface. My team leader advised to look through JSP.
What does JSP actually do?
Will I have to rewrite the User Interface in Web if I used JSP?
is there an more effective and efficient solution to do this job?
I would Appreciate a specific answer
I'm not sure what you mean by "specific answer", but here goes:
JSP is a kind of template language, based on Java, and a technology for dynamically generating HTML. It's a server side technology. Look here.
Yes, if you're going for a pure web/HTML solution, you'll need to completely rewrite the UI.
There are other frameworks for creating webapps, such as Vaadin or Play! Framework that may be "better" than JSP, but then there's a whole new API/framework to learn...
What does JSP actually do?
Will I have to rewrite the User Interface in Web if I used JSP?
is there an more effective and efficient solution to do this job?
and
I used SWING for the user interface.
and
exports and imports the table content to an excel sheet.
not, have to look at JavaFX 2
You will certainly need to rewrite the user interface if you convert to JSPs.
JSPs are essentially just a method for dynamically generating HTML (with the option to embed Java code to produce parts of the page).
It is still possible to run Swing applications from a web browser: you might want to take a look at Java Web Start. This will save you from having to do a complete rewrite.
1.) JSP is pretty much like PHP. It is server side scripting. When ever a browser request for a page (JSP page), server (mostly Tomcat or any application server which you deploy your JSP project) will generate HTML content using the JSP code. Mainly JSP consist of part HTML, JavaScipt (if you want dynamic stuff), and Java.
2.) As far as I know if you are aked to do it in JSP then you need to o all the client side work again in JSP. There you will be generating HTML UIs using Java codes. But you can use all the back end codes you used.
You may can use SWING in a Applet.
I personally do not have much experience working in jsp and struts2 tomcat server but I have a small task that I have to deal with a server in production. I looked at info on the internet for two nights but seems like i can't get the answer.
What I want to do is to open some static simple html pages pop-up from the jsp pages that already exist. Those jsp pages are currently located at /webapps/WEB-INF/tld/mainPage/indexMainPage.jsp
what I did was:
make some javascript functions so that when they click a button, i open a pop-up
function btn_openPopUp()
{
window.open("../popUp/test.html");
}
and put the test.html page at /webapps/WEB-INF/tld/popUp/test.html
The pop-up part works fine as it is just simplye javascript, but test.html is not displayed.
Struts Problem Report
Struts has detected an unhandled exception:
Messages:
There is no Action mapped for namespace / and action name test.
I have been looking at info online, and everything about struts is action based. Is there anyway I can open a page like on a regular server?
Pages under WEB-INF are not directly accessible to clients; put such pages under the root somewhere.
They can still be in sub-directories if it makes sense, just not under WEB-INF. If they must be under WEB-INF for some reason (which makes no sense for non-JSP pages) they can be streamed through an action like any other file--bit that'd be weird for HTML pages.