metachainer

MetaChainer

Simple implementation of chain of responsibility design pattern using annotations

Features

• Annotations to mark classes as chains and methods as chain steps

• Annotation to mark a method as a validator of chain step

• Possibility to stop the chain when errors occur or a step is invalid (breakOnErrors, breakOnInvalid attributes)

• Marking a method as Ensure, ensure method run when the chain breaks on errors

Example

Defining the chain:

package my.package.chain;

@ChainName("myChain")
public class MyChain {

    @ChainStep(order = 1, breakOnErrors = true)
    public void addOneToParameterOne(ChainContext context) {
    
	    Integer parameter1 = (Integer) context.get("myparameter1");

	    context.set("myparameter1", ++parameter1);
    }

    @ChainStep(order = 2, breakOnInvalid = true)
    public void addPostfixToParameterTwo(ChainContext context) {
	
	    String parameter2 = (String) context.get("myparameter2");
	    String newString = parameter2 + "myPostfix";
	
	    context.set("myparameter2", newString);
    }
    
    @StepValidator({"addPostfixToParameterTwo"})
	public boolean invalidMethodValidator(ChainContext context) {
		return true;
	}

	@ChainEnsure
	public void ensure(ChainContext context) {
		context.set("ensure", "Ensure method run always on errors!");
	}

}

Invoking the chain:

public void runMyChain() {
	
	ChainFactory factory = ChainFactory.instance();
	
	Chain chain = factory.create(MyChain.class);
	
	ChainContext context =
	chain.setParameter("myParameter1", 1)
		.setParameter("myParameter2", "myString")
		.start();
		
	// Do something with the context...
}

To Do

• Add todo tasks

Copyright

Copyright (c) 2011 Jorge Luis Pérez (jolisper@gmail.com). See LICENSE for details.