Creating and Using a Java Class | ColdFusion MX Professional Projects

To use Java in ColdFusion effectively, you need to handle the methods and properties defined in a Java class. Let's look at how to use the properties and methods in a simple Employee class using ColdFusion. The Employee class contains three properties, listed in Table C.2.

Table C.2: Properties in the Employee Class
Property	Use	Public or Private
FirstName	Retrieves or modifies the first name of an employee	Public
LastName	Retrieves or modifies the last name of an employee	Public
Salary	Retrieves the salary of an employee	Private

The Employee class contains the two methods listed in Table C.3.

Table C.3: Methods in the Employee Class
Method	Use	Public or Private
GetSalary()	Returns the current salary of an employee	Public
SetSalary()	Sets the current salary of an employee; accepts the salary value as an argument	Public

To create the Employee class and use it in your ColdFusion page, perform the following steps:

Create the Employee.java file containing this code for the Employee class:

 public class Employee {     public String FirstName;     public String LastName;     private float Salary; public void Employee() {     FirstName ="";     LastName ="";     Salary = 0.0f; } public void SetSalary(float salary_val) {     Salary = salary_val; } public float GetSalary() {     return Salary; } }

Note

You need to install the Java Software Development Kit (SDK) on your computer to compile a Java source code file to a Java class.

Save this code as Employee.java and compile it using the Java compiler javac.exe.
Place Employee.class in \CfusionMX\wwwroot\WEB-INF\classes.

To use the Employee class, create a ColdFusion page with the following code:

         <html>         <body>             <cfobject action="create" type="java"  name="employee">             <!--               Set the first name and last name of the employee by setting the firstname and lastname property of the Employee class             -->             <cfset employee.firstname="Jonathan">             <cfset employee.lastname="Cruise">             <!--               Display the name of the Employee             -->             <cfset firstname=employee.firstname>             <cfset lastname=employee.lastname>             <CFOUTPUT>               The name of the employee is #firstname# #lastname#.<br>             </CFOUTPUT>             <!--               Set the salary of the employee             -->             <cfset employee.SetSalary(24456.23)>             <!--               Get the current salary of the employee             -->             <cfset salaryval= employee.GetSalary()>         </body>         <! --         Display the name of the employee         -->         <cfoutput>             The salary of this employee is US$ #salaryval#         </cfoutput>         </html>

Save the ColdFusion page as callingjava.cfm.
View the ColdFusion page using the Web browser by typing this URL:

http://computer_name:8500/callingpage.cfm

Here, computer_name is the name of the computer where ColdFusion MX server is installed.

The Web browser displays the output, as shown in Figure C.3.

click to expand
Figure C.3: Calling and using a Java class in a ColdFusion page.

Using CFScript to Access a Java Object

You can also access and create a Java object in CFScript using the CreateObject() function. This function accepts two arguments:

Type. The type of the object to be created. For example, specify the type argument as Java to create a Java object.
Class. The name of the Java class to be used in CFScript.

The following code uses CreateObject() to call and use a Java class called Employee in CFScript:

 <HTML> <HEAD></HEAD> <BODY>     <CFSCRIPT>       myclass= CreateObject("java","Employee");       myclass.Firstname="Robert";       WriteOutput (myclass.Firstname);     </CFSCRIPT> </BODY> </HTML>