Controlling package dependencies in Java (Eclipse)

I have a Java project (in Eclipse) consisting of several packages. I would like to control the dependencies between packages so that, for example, one package couldn't use some other package in the project. The reason for this is that I am going to make a self-contained jar from a subset of packages.

Do I have to separate my project into several to achieve this or is there some开发者_运维百科 tool or Eclipse plugin that does it?

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Well since Aspectj is now an Eclipse Project, I guess an Aspectj solution qualifies as well. AspectJ is great for policy enforcements like that, because it lets you create compile-time warnings and errors based on pointcuts. And if you use the AspectJ Developer Tools, you get aspects up and running in Eclipse.

Here's a sample Policy Enforcement Aspect:

public aspect PolicyEnforcement {

  pointcut project1Call() : call(* com.project1..*.*(..));
  pointcut inProject1() : within(com.project1..*);
  pointcut project2Call() : call(* com.project2..*.*(..));
  pointcut inProject2() : within(com.project2..*);

  declare error : project1Call() && inProject2()
    : "Project2 is not allowed to access Project1";
  declare error : project2Call() && inProject1()
    : "Project1 is not allowed to access Project2";
}

Note: It's perfectly OK to use AspectJ like that during the development phase only without causing any runtime dependencies.