Java Reference
In-Depth Information
Figure 2.2
The HelloWorld class
The next section discusses writing both the interface and implementing class
shown in the figure.
2.2.1
Writing the HelloWorld MBean
The first step in developing the HelloWorld MBean is to write its Java interface.
The interface declares three methods: one getter , one setter , and an additional
method for printing the HelloWorld MBean's greeting. Normally, you might not
write an interface for a simple HelloWorld example class like this one. However,
as you will learn in chapters 4 and 5, JMX uses interfaces to describe the exposed
attributes and operations of an MBean.
Recall that a getter method is a class method with a name in the form of get-
Member() , and a setter method is a class method with a name in the form of set-
Member() . Think of the methods in a Standard MBean interface as the description
of the implementation class. Put simply, you should be able to understand the
purpose of the methods by their names. In addition, the getter and setter meth-
ods define the member variable access granted to objects that use the MBean. By
creating a getter method for a member variable, you grant read access to it. A set-
ter method grants write access. As you can see from the following interface, this
MBean is quite simple:
package jmxbook.ch2;
public interface HelloWorldMBean
{
public void setGreeting( String greeting );
public String getGreeting();
public void printGreeting();
}
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