Question

我想通过杰克逊（Jackson）解析YAML文件，但是遇到一个问题，即其中一个属性（我们称其为“事件”）具有一个名为“ type”的字符串和一个针对不同事件而有所不同的“ properties”对象。我的问题是我需要为此YAML定义POJO。因此，我想用VariableObject定义一个Hashmap，它可以是某些预定义的类中的任何一个（为简便起见，假设是Shipping和Inventory）。

如何实现这样的Hashmap？

public class Event {
    private static String type;
    private static Map<String, VariableObject> properties;

    public static void main(String[] args) {
        Inventory inventory = new Inventory("inventoryName", 13);
        properties.put("Inventory", inventory);
        Shipping shipping = new Shipping("shippingName", true);
        properties.put("Shipping", shipping);
    }
}


public class Inventory {

    private static String name;
    private static int someNumber;

    public Inventory(String name, int someNumber) {
        this.name = name;
        this.someNumber = someNumber;
    }
}


public class Shipping {

    private static String name;
    private static boolean someBoolean;

    public Shipping(String name, boolean someBoolean) {
        this.name = name;
        this.someBoolean = someBoolean;
    }
}

Answer 1

您要说的是简单的Object。这是最具体的普通超类：

private static Map<String, Object> properties;

其他解决方案是使Inventory和Shipping实现一些通用接口，例如Named，并将其用作HashMap中的类型参数。

Answer 2

一种方法是使Shipping和Inventory实现相同的接口（例如cas中的VariableObject）

public class Event {
    private static String type;
    private static Map<String, VariableObject> properties;

    public static void main(String[] args) {
        Inventory inventory = new Inventory("inventoryName", 13);
        properties.put("Inventory", inventory);
        Shipping shipping = new Shipping("shippingName", true);
        properties.put("Shipping", shipping);
    }
}

public interface VariableObject{
//you can define common methods here if you want
}


public class Inventory implements VariableObject{

    private static String name;
    private static int someNumber;

    public Inventory(String name, int someNumber) {
        this.name = name;
        this.someNumber = someNumber;
    }
}


public class Shipping implements VariableObject{

    private static String name;
    private static boolean someBoolean;

    public Shipping(String name, boolean someBoolean) {
        this.name = name;
        this.someBoolean = someBoolean;
    }
}

如何用不同的对象作为值来实现Java Hashmap

2 个答案: