Get output of java file into jsp page

Question

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!

The point was that you shouldn't have any Java source in your JSPs. There's no reason to do it. Use a custom tag, either JSP- or Java-based, or use JSTL's fn to call functions. Which is better depends on the specifics. Both are searchable and have examples on how to get page output. Obviously System.out isn't the same as the JSP's PrintWriter, though. — Dave Newton
– Dave Newton, Commented Apr 29, 2014 at 14:56

zero298 · Accepted Answer · 2014-04-29 14:59:16Z

2

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.

edited Apr 29, 2014 at 14:59

answered Apr 29, 2014 at 14:47

zero298

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2 Comments

SpringLearner Over a year ago

are you sure it will print in the jsp page.test() has System.out.println();

zero298 Over a year ago

@JqueryLearner I think the goal should be to not use the System.out.println(); at all.

Half_Duplex · Accepted Answer · 2014-04-29 15:33:41Z

1

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.

edited Apr 29, 2014 at 15:33

answered Apr 29, 2014 at 14:56

Half_Duplex

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5 Comments

nj-ath Over a year ago

But here I cannot get it to return more than 1 string! My point is whatever i print onto that function in the class should be printed on the browser..

Half_Duplex Over a year ago

I am not sure I follow you, you can call that <%=TestJava.getAString()%> method that returns a String as many times as you want, or any other number of functions you've created to return markup. Also, nothing stops you from doing something like this either.. <%=System.out.println("Print this in html...")%>

Half_Duplex Over a year ago

NOTE: To everyone saying this should be avoided... I agree, but it's also fundamental to understanding how JSP works and that appears to me what is needed here.

nj-ath Over a year ago

Ok, let me explain.. Let's say this is a simple interactive application, so I might need to input some random files and output messages accordingly (in different places) and I would like to do this in a single function, so when I call that function in the scriptlet, it should simply execute and print whatever is required to be printed onto the browser!

Half_Duplex Over a year ago

JSP doesn't work that way, the JSP code in your .jsp file is used once to build the page when the .jsp file is requested by the client. Once the servlet container builds the HTML based on the .jsp code and serves it, that's it, you are no longer able to make those calls. If you're asking how you can incorporate user input into this process, you need to read about servlets and mapping them to the JSP page which will allow you to pass parameters to the soon to be generated jsp page. I think you need to read more about JSP and servlets and also the difference between them and AJAX may be helpful.

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