Java Server Pages

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Java Server Pages

References

Tutorials Point, Learn JSP, http://www.tutorialspoint.com/jsp/, accessed 3/5/2016.
Wikipedia, Java Server Pages, https://en.wikipedia.org/wiki/JavaServer_Pages, accessed 3/5/2016.

Definitions

Java Server Pages (JSP) is a server-side technology for creating dynamically generated web pages.
JSP operates similarly to PHP, Ruby on Rails, ASP.Net and C#.
JSP uses Java as its server-side language.
To deploy JSP, use a server such as Apache Tomcat.
Some other popular JSP application servers:
Glassfish JBoss WebSphere Wildfly Geronimo Blazix

Tomcat Installation

Tutorials Point directions for installing Tomcat:
www.tutorialspoint.com/jsp/jsp_environment_setup.htm
To display JSP example pages, place the project files in this folder:
```
c:/apache-tomcat-7.0.68/webapps/ROOT
```

First Example

Create a new folder named first in this ROOT folder. Then create a new file named first.jsp in ROOT/first. Place this course code in first.jsp:

<!DOCTYPE html>
  <html>
    <head>
      <title>First Example</title>
    </head>

    <body>
    <% out.println("username: sjost;");
       out.println("Running first program in JSP."); %>

    <br />
    <br />

    <% out.println(new java.util.Date( )); %>
  </body>

</html>

Now open a Command Prompt Window in the folder c:/apache-tomcat-7.0.68/bin and enter
```
> startup
```
Then view the JSP page in a Web browser at localhost:
```
http://localhost:8080/first/first.jsp
```
You should see this text displayed in the browser:
username: ssmith; Running first program in JSP.

Sat Mar 05 13:17:36 CST 2016
Notice that there are two types of statements in the first.jsp file:
1. HTML statements, which are used just like an ordinary HTML file
2. Java statements, which are placed in <% ... %> delimiters, which are called scriptlet delimiters.
Also notice that System.out.println is not used for printing to a Web page. The builtin object out is used, which is a JSPWriter object, used for writing content to the response page.
The Java statements placed within <% ... %> delimiters should not have any return value or values. This situation is similar to the <% ... %> Rails delimiters.

Actually, JSP has five different types of delimiters:

Delimiter Type	Delimiter Symbols	Example
Scriptlet	<% ... %>	<% out.println("This is a test"); %>
Expression	<%= ... %>	<%= new Date( ) %>
Declaration	<%! ... %>	<%! public int n = 5; %>
Directive	<%@ ... %>	<%@page import="java.util.Calendar" %>

JSP even has a new format that makes the differences between these types of delimiters explicit:

Standard Format New Format

<% ... %> <jsp:scriptlet> ... </jsp:scriptlet>

<%= ... %> <jsp:expression> ... </jsp:expression>

<%! ... %> <jsp:declaration> ... </jsp:declaration>
Try adding this directive line to the beginning of the First Example source code:
```
<%@page import="java.util.Calendar" %>
```

Standard Format	New Format
<% ... %>	<jsp:scriptlet> ... </jsp:scriptlet>
<%= ... %>	<jsp:expression> ... </jsp:expression>
<%! ... %>	<jsp:declaration> ... </jsp:declaration>

Also add these lines of code immediately before the </body> tag:

<br />
<%
    Calendar cal = Calendar.getInstance( );
    int m = cal.get(Calendar.MONTH);
    int d = cal.get(Calendar.DAY_OF_MONTH);
    int y = cal.get(Calendar.YEAR);
%>
<%= String.format("%d/%d/%d", m + 1, d, y) %>

Some Tomcat Examples

The Tomcat Examples are located in this folder:
```
c:/apache-tomcat-7.0.68/webapps/examples
```
Copy this entire examples folder and its contents into the ROOT folder:
```
c:/apache-tomcat-7.0.68/webapps/ROOT
```
Start the Tomcat server if it is not already running. Then view the index page of the examples folder like this:
```
http://localhost:8080/index
```
Click on the JSP Examples link. Then look at these examples:
Hello World Tag Repeat Tag Book Snoop
We already saw how to use the builtin object JSPWriter object out for writing to the browser document. Here are three other builtin objects:
request    HttpServletRequest object that provides access to the HTTP request.
response    HttpServletResponse object that provides access to the HTTP response.
session    HttpSession object that contains the data from an individual user's session.

ClaimForm Example

This example shows a simple HTML/JSP project for submitting an insurance claim.
Reference: David Parsons, Dynamic Web Application Development using XML and Java, Cengage Learning, 2008.

In the c:/apache-tomcat-7.0.68/webapps/ROOT folder create a new folder named claimform.

Add these three files to the insuranceclaim folder:

File: claimform.htm

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Insurance Claim Form</title>
    <link rel="stylesheet" 
          href="claimform.css" />
  </head>

  <body>
    <h2>Insurance Claim Form</h2>
    <form action="claimserverpage.jsp" method="get">
      <table>
        <tr>
          <td><label for="policynumber">
            Policy Number:</label></td>
          <td><input type="text" id="policynumber"
                     name="policynumber" />
        </tr>

        <tr>
          <td><label for="claim">
            Amount Claimed:</label></td>
          <td><input type="text" id="claim"
                   name="claim" />
        </tr>

        <tr>
          <td></td>
          <td><input type="radio" name="type"
                     id="buildings" 
                     value="buildings" />
              <label for="buildings">
                Make a buildings insurance claim.
              </label></td>   
        </tr>

        <tr>
          <td></td>
          <td><input type="radio" name="type"
                     id="contents" value="contents" />
          <label for="contents">
            Make a contents insurance claim.
          </label></td>   
        </tr>
       
        <tr>
          <td><label for="description" 
                     name="description">
                Description of claim:
              </label></td> 
              <td><textarea id="description" 
                        name="description"
                        rows="5" cols="30">
              </textarea></td>
        </tr>

        <tr>
          <td></td>
          <td><input type="submit" 
                     value="Submit" /></td>
        </tr>
      </table>
    </form>
  </body>
</html>

File: claimform.css

/* CSS file for claimform.htm */

* { font-family: Helvetica; }

body { color: navy;
	     background-color: #f2f2ff; }
     
h2 { color: #600000; }

File: claimserverpage.jsp

<?xml version="1.0" ?>

<%@page import="java.text.NumberFormat" %>
<%
  String policyNumber = 
    request.getParameter("policynumber");
  String claimValue = 
    request.getParameter("claim");
  String claimType = 
    request.getParameter("type");
  String description = 
    request.getParameter("description");

  // Convert claimValue to a double
  double valueOfClaim = 0.0;
  try {
      valueOfClaim = 
          Double.parseDouble(claimValue);
  }
  catch(NumberFormatException e) {
    e.printStackTrace( );
    System.out.println(claimValue +
        " is not a valid number.");
  }
%>

<!DOCTYPE html>

<html lang="en">

  <head>
    <title>Insurance Claim Details</title>
    <link rel="stylesheet" 
          href="claimform.css" />
  </head>

  <body>
    <h2>Insurance Claim Details</h2>

    <p>Thankyou for submitting 
      your insurance claim.</p>
    <p>Here are the details 
      you entered.</p>
    <p>
      Policy number: <%= policyNumber %><br />

    <% NumberFormat currencyFormat = 
         NumberFormat.getCurrencyInstance( );
       String valueOfClaimFormatted = 
         currencyFormat.format(valueOfClaim); %>

      Value of Claim: <%= valueOfClaimFormatted %><br />
      Type of insurance policy: <%= claimType %><br />
      Description of claim: <%= description %>
    </p>

  </body>
</html>