Suggestions for implementing method invocations based on the parameter passed to servlet

Question

Hi,

I would like to get some suggestions on implementing a solution that invokes ejb methods based on the parameters I pass to a servlet.

I have a web project and an ejb 3.0 project. The ejbs are invoked from the servlet in the web project.

The ejbs are invoked based on the parameters I pass to the servlet. For every action I need to perform, I pass a definite parameter say, task to the servlet. For example, if the task equals fetchEmployee, it will invoke a specific method of a bean for eg:- fetchEmployeeDetails().If the task equals deleteEmployee, it should invoke a different bean method.

I have the following options:

• if/else or switch case method. This is becoming messy and unmanageable when the number of tasks increased like anything.

• mapping the tasks and the bean classes in an xml config file, and then read it using Digester

• Using a ServletFilter to perform some action based on the parameters passed.

Can someone kindly suggest a clean/elegant method to implement this?

Answer 1

You could use dynamic method invocation on your ejb.

You can ask the Class of the interface for a method handle based on the name and parameter signature.

Method method = bean.getClass().getMethod(task,paramTypes);

It gets a bit messy to map the parameters, unless you make your life easy and always pass a hashmap or similar. You'll get only strings from the request anyway so sanitation and translation still must be done anyway.

Then you invoke the method :

Object[] args = new Object[]{paramMap};
String result = method.invoke(method, args);