Question

In playframework, it uses javassist library to let the public fields of a class can be used as property.

See the example:

public class User {
    public String name;
}

User user = new User();
user.name = "Freewind"
System.out.println(user.name);

In compilation time, play enhanced the bytecode with javassist, the final code is similar to:

public class User {
    private String name;
    public String getName() { return this.name; };
    public void setName() { this.name = name; };
}

User user = new User();
user.setName("Freewind");
System.out.println(user.getName());

You can see not only the field name has getter and setter, but also the invocations of it changed to getters and setters.

I wonder if there is any other way to do the same (use other things than javassist)?

I found Annotation Processing Tool, but I’m not sure it can do it.

Or aspectj? Or something else?

Answer 1

You can look at Project Lombok, which does something similar, but with annotations. With project lombok you do need to use the getters and setters in your own code.