如何使用 Moxy 和 Jersey 从 HashMap 返回 JSON 对象

Yeah MOXy and Maps don't work well. It's sad, as JSON is nothing more than mapped key/value pairs. If you want to use MOXy, you will need to use an XmlAdapter. In which case, the way you want the JSON, you will need to create a type (class) that has the name of all possible preferences. Arbitrary key value pairs should be in the form you require, but since MOXy can't do maps, you'll need to map it to your own type. For instance

public class PreferencesAdapter extends XmlAdapter<Preference, HashMap<String, String>> {

    @XmlRootElement
    public static class Preference {
        public String language;
        public String country;
    }

    @Override
    public HashMap<String, String> unmarshal(Preference p) throws Exception {
        HashMap<String, String> map = new HashMap<>();
        map.put("language", p.language);
        map.put("country", p.country);
        return map;
    }


    @Override
    public Preference marshal(HashMap<String, String> v) throws Exception {
        Preference p = new Preference();
        p.language = v.get("language");
        p.country = v.get("country");
        return p;
    }
}

你的 DTO

@XmlRootElement
public class User {
    @XmlJavaTypeAdapter(PreferencesAdapter.class)
    public HashMap<String, String> preferences;
}

但是，如果我们要做这一切，为什么不首先使用 Preferences 对象而不是 Map?那是一个反问.我完全理解你为什么不这样做.但这是 MOXy 的限制之一，因为它让我们在引擎盖下对 JAXB 感到沉重，而 JAXB 从来没有很好地与 Map 配合使用，这很可悲，就像我说的那样，JSON 真的只不过是一个键值的 Map.

<dependency>
    <groupId>org.glassfish.jersey.media</groupId>
    <artifactId>jersey-media-json-jackson</artifactId>
    <version>${jersey.version}</version>
</dependency>