groovy protected属性不能在子类中重写

Question

子类调用父保护方法,期望返回受保护的覆盖属性.但返回父母的财产.

//父类:

package tz

import java.util.List;

class AbstractController {
    protected List keywordFilter = []
    protected String methodKey(){
        return "\t[method]parent,$keywordFilter,"+keywordFilter.toString()
    }
    def closureKey(){
        return "\t[closure]parent,$keywordFilter,"+keywordFilter.toString()
    }
}

//子类:

package tz

import java.util.List;

class SubController extends AbstractController{
    protected List keywordFilter = ['a']
    public SubController(){
    }

    public void test(){
        println "subCall:"+methodKey()+closureKey()
    }
    def test2 = {
        println "c,$keywordFilter,"+methodKey()+closureKey()
    }

    public static void main(String[] args) {
        def s = new SubController()
        s.test()
        s.test2()
    }
}

//输出:

subCall:[method]parent,[],[]    [closure]parent,[],[]
c,[a],  [method]parent,[],[]    [closure]parent,[],[]

Answer 1

在Java和Groovy中,子类中的字段不会被覆盖.基类版本只是由子类版本隐藏.实际上,您在类中获得了两个具有相同名称的字段.基类方法将看到基类字段和子类方法将看到子类字段.

解决方案通常是将字段包装在getter方法中.在groovy:

class AbstractController {
    protected List getKeywordFilter() { [] }
    ...
}
class SubController extends AbstractController {
    protected List getKeywordFilter() { ['a'] }
    ...
}

遵循groovy属性约定,您仍然可以引用它,"$keywordFilter"因为它将自动调用getter.