public interface Sourcable {

    public void go();
}

public class Source implements Sourcable {

    public void go() {
        System.out.println("Source method go()");
    }

}
public class Decorator implements Sourcable {

    private Sourcable sourcable;
    
    public Decorator(Sourcable sourcable){
        this.sourcable = sourcable;
    }
    
    public void go() {
                //这里可以有你的处理
        sourcable.go();
                //这里可以有你的处理
    }

}