Spring Dynamic Properties

This project provides support for dynamically changing properties in spring applications.

Please be aware that this project is still in alpha phase.

Usage

Annotate setter of your spring components with @DynamicProperty:

class Service {

    @DynamicProperty("x")
    public void setX(int x) {
        this.x = x;
    }

}

Whenever a property source propagates a change to the dynamic property x this method is called with the new value.

If you need a callback whenever one or more properties of a component where changed you can annotate a no-argument method with @AfterDynamicPropertiesSet. This method will be called exactly once, even when multiple properties changed at a time. If you need to do expensive work when properties change (i.e. create a new connection pool) this is the place to do it.

How it works

TODO

Design Goals

I wanted a solution that is only dependent on annotations but does not introduce some new wrapper type for dynamic properties. That is, instead of

class Service {

    private DynamicProperty<Boolean> myProperty; // magically set somewhere

    public void foo() {
        if (myProperty.get()) { // non-transparent: call to get() is always required
            // do something
        }
    }

}

you can write

class Service {

    private boolean myProperty;

    public void foo() {
        if (myProperty) {
            // do something
        }
    }

    @DynamicProperty("myProperty")
    public void setMyProperty(boolean myProperty) {
        this.myProperty = myProperty;
    }

}

This may seem more verbose, but doesn't need new special types and - more importantly - works without a special framework by just calling the appropriate setter.

Requirements

• Java 7
• Spring 4

License

See LICENSE.