强制GSON使用特定的构造函数

问题描述

public class UserAction {
    private final UUID uuid;
    private String userId;
    /* more fields, setters and getters here */

    public UserAction(){
        this.uuid = UUID.fromString(new com.eaio.uuid.UUID().toString());
    }

    public UserAction(UUID uuid){
        this.uuid = uuid;
    }
    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final UserAction other = (UserAction) obj;
        if (this.uuid != other.uuid && (this.uuid == null || !this.uuid.equals(other.uuid))) {
            return false;
        }
        return true;
    }

    @Override
    public int hashCode() {
        int hash = 7;
        hash = 53 * hash + (this.uuid != null ? this.uuid.hashCode() : 0);
        return hash;
    }
}

我使用Gson来串行化和反序列化这个类。如今天，我不得不在这个对象中添加最后一个UUID。我没有问题序列化。我需要强制gson在反序列化时使用 public UserAction（UUID uuid）构造函数。

推荐答案

您可以实现自定义的并向GSON注册。

You could implement custom JsonDeserializer and register with GSON.

class UserActionDeserializer implements JsonDeserializer<UserAction>() {
    public UserAction deserialize(JsonElement json, Type typeOfT,
        JsonDeserializationContext context) throws JsonParseException {
        return new UserAction(UUID.fromString(json.getAsString());
}

GsonBuilder gson = new GsonBuilder();
gson.registerTypeAdapter(UserAction.class, new UserActionDeserializer());

请注意，此代码尚未经过测试。

Bear in mind that this code has not been tested.

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