java - 从 Modelclass 层次结构的顶层调用 setter

Question

假设您有一个模型类层次结构，例如

    public class TopLevel {
        private MiddleLevel middleLevel = null;

        public TopLevel() {
            middleLevel = new MiddleLevel();
        }

        public MiddleLevel getMiddleLevel() { return middleLevel; }
    }

    public class MiddleLevel {
        private LowLevel lowLevel = null;

        public MiddleLevel () {
            lowLevel = new LowLevel();
        }

        public LowLevel getLowLevel() { return lowLevel; }
    }

    public class LowLevel {
        private Value value = null;

        public LowLevel() {
            value = new Value();
        }

        public Value getValue() { return value; }
    }

    public class Value {
        private String stringValue = "ItsAValue";
        private String doubleValue = 1.0d;
        private String integerValue = 4321;

        public void setStringValue(String value) {
            stringValue = value;
        }
    }

当然还有具有不同属性的其他类。例如。该层次结构由 Jaxb 创建并实例化。

现在，我想在值类中设置一个值。当然我可以执行类似的操作:

    TopLevel topLevel = new TopLevel();
    topLevel.getMiddleLevel().getLowLevel().getValue().setStringValue("NewValue");

有没有办法简化或概括这一点，例如能够调用所有这些类对象的“路径”来设置内部的值？这是一些伪代码，我的意思是:

    public class Anotherclass {
        public static void main(String[] args) {
            TopLevel topLevel = new TopLevel();
            setStringValueByPath("topLevel/middleLevel/lowLevel/value/stringValue", "newValue");
            setDoubleValueByPath("topLevel/middleLevel/lowLevel/value/doubleValue", 5.0d);
            setIntegerValueByPath("topLevel/middleLevel/lowLevel/value/integerValue", 1234);
        }

    }

非常感谢

亚历克斯

Answer 1

好吧，如果有人感兴趣，我想我找到了一个我一直在寻找的解决方案:

基于Java.reflection的递归方法:

public class ReflectionSetter {
    private static List<Field> getFields(Object object) {
        List<Field> fields = new ArrayList<>();
        fields.addAll(Arrays.asList(object.getClass().getDeclaredFields()));
        return fields;
    }

    private static Field hasField(Object object, String fieldName) {
        for (Field f : getFields(object)) {
            if (f.getName().equalsIgnoreCase(fieldName)) return f;
        }
        return null;
    }

    public static void setValue(Object object, String path, String newValue) throws IllegalArgumentException, IllegalAccessException {
        if (path.contains("/")) {
            int pos = path.indexOf('/');
            String first = path.substring(0, pos);
            String rest = path.substring(pos+1);
            Field f = ReflectionSetter.hasField(object, first);
            if (null == f) throw new IllegalArgumentException("Path not found: " + path);
            f.setAccessible(true);
            Object obj = f.get(object);
            setValue(obj, rest, newValue);
        } else {
            Field f = ReflectionSetter.hasField(object, path);
            if (f == null) throw new IllegalArgumentException("Field not found: " + path);
            // if found -> set value
            f.setAccessible(true);
            f.set(object, newValue);
        }
    }
}

现在，您可以通过路径设置值。用法:

    TopLevel topLevel = new TopLevel();
    ReflectionSetter.setValue(topLevel, "middleLevel/lowLevel/value/myValue", "NewValue");