Jackson和Iterable：如何反序列化

我有一个类Box，它具有一个实现elements类型的字段（请参见下面的代码）。后者包含也称为ElementsIterableListelements

如果我设置字段elements的Elements是private，那么系列化只会把它作为一个数组，而不是一个POJO

由版本A完成的序列化

{
  "elements" : [ "a", "b", "c" ]
}

但是，我无法反序列化此字符串。错误是：

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `ser_deser_test.Elements` out of START_ARRAY token
 at [Source: (String)"{
  "elements" : [ "a", "b", "c" ]
}"; line: 2, column: 16] (through reference chain: 

相反，如果将I设置elements为public，则elementsof Box将被视为POJO，并且其中有两个有趣的层次elements。但是，反序列化在这种情况下有效。

版本B的序列化

{
  "elements" : {
    "elements" : [ "a", "b", "c" ]
  }
}

我的问题是：如何获得反序列化才能用于版本A？

码

Box.java

package ser_deser_test;

public class Box {
    public Box() {
        super();
    }

    public Elements elements;

    public Box(Elements elements) {
        super();
        this.elements = elements;
    }

}

Elements.java

package ser_deser_test;

import java.util.Iterator;
import java.util.List;

import com.fasterxml.jackson.annotation.JsonFormat;

public class Elements implements Iterable<String> {
    // private List<String> elements; // Version A
    // public List<String> elements;  // Version B

    public Elements() {
        super();
    }

    public Elements(List<String> elements) {
        super();
        this.elements = elements;
    }

    @Override
    public Iterator<String> iterator() {
        return elements.iterator();
    }

}

TestSerDeser.java

package ser_deser_test;

import java.io.IOException;
import java.util.Arrays;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

public class TestSerDeser {

    public static void main(String[] args) {
        Elements elements = new Elements(Arrays.asList("a", "b", "c"));
        Box      box = new Box(elements);

        ObjectMapper om = new ObjectMapper();

        om.enable(SerializationFeature.INDENT_OUTPUT);
        try {
            // Serialize
            String s = om.writeValueAsString(box);

            // Deserialize
            Box box2 = om.readValue(s, Box.class);

            boolean dummy = false;

        } catch (JsonProcessingException e2) {
            e2.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }         
    }
}