I've read most of the online resources for building a simple "Hello World" app using Java and Struts 2. I understand the simple stuff. My problem is that I'm trying to expand that learning and build a large scale app, and I just don't see how to connect the dots.
Scenario:
I've got three views to begin with: Home.jsp, MyAccount.jsp, Contact.jsp. Each has the following HTML:
<%#page contentType="text/html" pageEncoding="UTF-8"%>
<%#taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript" src="js/common.js"></script>
...
</head>
<body>
<!-- If logged in, says "hello <s:property name="username">"
Else displays link to .show() #loginPane -->
<div id="accountHeader">...</div>
<!-- Displays <s:textfield> tags and <s:submit> tag to accept username and password -->
<div id="loginPane" style="display: none">...</div>
<header>...</header>
<nav>...</nav>
<!-- Displays view-specific content that includes Struts 2 tags -->
<div id="content">...</div>
<footer>...</footer>
</body>
</html>
So, obviously there is a lot of code common to each view (anything not in #content div).
How do I architect these views for code reuse?
What I've tried:
Placing common code in common.js and using jQuery .html() calls to populate <div>s. [Doesn't work because jQuery cannot generate code with <s:> tags.]
Using only one .jsp view file and placing view-specific code in common.js to be generated with jQuery .html() calls. [Doesn't work for the same reason -- jQuery cannot generate code with <s:> tags.]
Placing all view components in .jspf files and loading each with jQuery .load() calls from common.js. [Doesn't work -- I'm guessing the .jspf files need the Struts 2 <%taglib ...%> included in each, but jQuery .load() treats the <%taglib ...%> as text to be displayed in the <div>... and also fails to properly generate the <s:> tags.]
What is the proper way to do this? How do I architect my view(s) for code reuse?
My apologies if this isn't the proper forum to ask for architecture help, but I'm really struggling here... Perhaps point me to a more appropriate forum or an online tutorial that addresses this type of architecture?
Thanks in advance!
I've used several methods to accomplish this type of re-use of code including Tiles and tooling around with Sitemesh and other template frameworks. What I've found is that, much as Steven Benitez, in the end I preferred to use JSP taglibs, native Struts2 taglibs, and JSTL to essentially build out my own templating routines. The main reason I prefer this is that there tends to be less overhead and it's been a lot easier to maintain and extend in the long run.
Generally What I do is define my base template, index.jsp for example, and then in each independent Struts controller class I will define what page fragment is used. I try to split my controllers up in such a way that each page or function is handled by a single controller and I implement the Preparable interface. This way I can set a parameter for the page to reference. Sometimes I set it as a variable in the controller class, sometimes a sessions variable depending on what type of stating I need for the application.
Once I have a variable with the page to reference, I can just use a JSTL import or Struts include tag to load the page fragment.
The controller class would look something like this:
#Results({
#Result(name = "success", location = "/WEB-INF/content/index.jsp")
})
public class IndexController extends RestActionSupport implements Preparable{
private String page;
private String pageTitle;
#Override
public void prepare() throws Exception {
page = "home";
pageTitle= "My Home Page";
}
...
}
And then the JSP would look something like this:
<%# taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%# taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%# taglib prefix="s" uri="/struts-tags"%>
<html>
<head>
<title> ${pageTitle}</title>
</head>
<body>
<c:import url="${page}.jsp" />
</body>
</html>
EDIT: Fragment page example:
<%# taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%# taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%# taglib prefix="s" uri="/struts-tags"%>
<div>
<h1>Welcome Home!</h1>
</div>
<script type='text/javascript'>
$(document).ready(function() {
// page specific scripting if needed
);
</script>
You can encapsulate common template code in JSP tag files, as explained in this answer or you can also use decorator frameworks such as Tiles or SiteMesh to do this.
Personally, I prefer JSP tag files. Do not attempt to write out HTML with jQuery or to put all of your code into a single JSP.
Related
Is there any way I could use jstl inside a java function? Basically, what I want is I would just call the connectTodb() function in a jsp page where I need a connection. However, I do not know how.
Can I do this for example?
connectTodo() {
<sql:setDataSource driver="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost/database_name"
var="localSource"
user="database_user"
password="database_password"/>
}
How do I call this method in my jsp file? Or if I can't do this, how do I connect to the database with just a function? Help me out, thank you!
You can write functions in JSP, but that is generally discouraged. Normally you would create tags and/or fragments. You posted one,
<sql:setDataSource driver="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost/database_name"
var="localSource"
user="database_user"
password="database_password"/>
That is made available in a jsp with the <%# %> block like
<%# taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql"%>
<html>
You could write your own tag file like initDB.tag
<%# taglib prefix="db" tagdir="/WEB-INF/tags" %>
<%# taglib uri="http://java.sun.com/jsp/jstl/sql" prefix="sql"%>
<sql:setDataSource driver="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost/database_name"
var="localSource"
user="database_user"
password="database_password"/>
and then you can use it like
<db:initDB />
Finally, you might check if your server has a connection pool that you can access from a JNDI name.
Hi i am trying to include a new jsp page on my jsp page in every 10 sec how can i achieve this
i am able to include page but not including according to time
Here is my code
<%# page language="java" contentType="text/html;charset=UTF-8" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html>
<head>
<title>Untitled Document</title>
section
{height:70%; background-color:blue; display:block; overflow:auto;}
section .push {height:500px;}
</style>
</head>
<body>
<form action="F1.jsp" method="post">
<%# include file="F2.jsp" %>
<footer>footer</footer>
</form>
</body>
</html>
How can i achieve this
Thanks in advance
If you want to include more content or refresh a section of the page you need to use browser side JavaScript to pull new content from the server.
Once you display something using JSP, that is final. It cannot change unless you provide the mechanisms to change. You can set a refresh rate of your JSP to auto refresh and display each time a new content.
Or you can use AJAX.
How to do it using ajax (I prefer the JQuery version) can be found here at the answer with 5 upvotes
You can set interval in Javascript.
syntax:
setInterval(function(){
// code //
},10000);
In the code you can use Ajax calls which pool the content of JSP from the server.
I was trying to write a JSP page. But i have read many times that source code within JSP page is a bad practice. So then I tried to write a different class in the same package and call it within that JSP page.
Here's the JSP code:
<jsp:useBean id="link" scope="application" class = "tms.TestJava" />
<%
TestJava t=new TestJava();
t.test();
%>
and here's the class code:
public class TestJava {
public void test() throws IOException
{
System.out.println("sdds");
}
}
I have imported the class into JSP page.
Now the problem is that when I use System.out.println in the class (test method), it gets printed onto the console and I want it to print it to the JSP page. How can I achieve this? Is there a seperate method? Do I have to make the class a servlet?
Thanks!
Try using a tag library: JSTL
Specifically:
<%# taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<title><c:out> Tag Example</title>
</head>
<body>
<c:out value="${'<tag> , &'}"/>
</body>
</html>
Or better yet, since you are using JavaBeans already, refactor so that you aren't using System.out() anymore. The idea is that you want to display properties of your bean in your page. Consider: JavaBeans So Do something like this:
Java
public class Course{
private String code = "Math";
public String getCode(){
return code;
}
}
Jsp
<jsp:useBean id="course" class="com.javaBeans.Course" />
<jsp:getProperty name="course" property="code"/>
Chiefly, you don't want to just System.out() to a page. The page should be a view of the data of components on the sever which in this case is the bean.
I think you're going about this the wrong way, but here is a possible solution...
<head>
<%# page language="java" import="tms.TestJava"%>
</head>
<body>
<%=TestJava.getAString()%>
<%=TestJava.getAString()%>
<%=TestJava.getAString()%>
<%=TestJava.getAString()%>
<%=TestJava.getAString()%>
</body>
public String getAString(){
return "<li></li>";
}
If your goal is to build dynamic JSPs, you will probably want to look into JSTL as someone above mentioned, look into defining your own tags, etc. I don't think very much new dev is using scriplet code.
I'm very new to Spring and can't seem to figure out what's wrong here. I'm sure it has to be something simple, but anyway:
I was going through the tutorial on this page, and I have nearly identical code. After pulling down the Apache Commons library and the JSTL stuff, I was in business. Everything works, down to it actually using the jsp I specified as the view, but the variable "message" in the controller is not being displayed when the site is rendered. It's not because of the expression language stuff, either, because I'm not getting the ${message} text displaying either. It's just a blank page.
The only reason I know that the jsp is actually being triggered is because I put a title in there that is no where else and it is being used on page display. I also know that the variable is being set in the controller and the action is being called because of a simple sysout that I put in the mapped function.
Thanks for any help!
EDIT
Here's the jsp:
<%#page contentType="text/html" pageEncoding="UTF-8" isELIgnored="false"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>om nom JSP Page</title>
</head>
<body>
${message}
</body>
</html>
And the controller:
package org.me.home.controllers;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.portlet.ModelAndView;
#Controller
public class SomeController {
#RequestMapping("/somepage")
public ModelAndView someAction() {
String mymsg = "Saying hi!";
System.out.println(mymsg);
return new ModelAndView("somepage", "message", mymsg);
}
}
Try to use such a construction:
<%# taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
...
<c:out value="${message}" />
And are you sure, that the problem is in displaying? Is page loaded fine, I mean is all other HTML displayed on page, besides "message"?
EDIT
Try to use org.springframework.web.servlet.ModelAndView instead of
org.springframework.web.portlet.ModelAndView
Your tomcat maybe using the wrong jstl.jar. Under your tomcat lib folder, check if your jstl.jar is the same version you are using with your project.
I am trying to figure out how to most effectively reuse JSP code.
I love the way Rails/erb works in that way ... with yield, layout, content_for
Example:
main_layout.erb.html
<html>
<head><%= yield :head %></head>
<body><%= yield %></body>
</html>
use
<% content_for :head do %>
<title>A simple page</title>
<% end %>
<p>Hello, Rails!</p>
in controller
layout "main_layout"
What is the closest I can get to this with JSP (without using extra frameworks)? I know about JSP include but that's not really the same as yield.
Any suggestions?
Thanks
I'm not familiar with what yield and content_for provide, but JSP tag files allow you a more robust way to template pages than JSP includes.
Example:
layout.tag
<%# tag body-content="scriptless" %>
<%# attribute name="pageTitle" required="true" type="java.lang.String" %>
<html>
<head>
<title>${pageTitle}</title>
</head>
<body>
<jsp:doBody/>
</body>
</html>
An individual JSP
<%# taglib prefix="z" tagdir="/WEB-INF/tags" %>
<z:layout pageTitle="A simple page">
<p>Hello, JSP!</p>
</z:layout>
Just place your layout.tag in the /WEB-INF/tags directory. You can use any available prefix you want, I just used "z" for the example.
While you mentioned wanting no frameworks on top of stock jsp, the Layout functionality of the Stripes Framework does pretty much exactly what you're asking for.