java - 由于InvalidDefinitionException，javamoney的CurrencyUnit不能用作字段的类并被Jackson反序列化

Question

我有一个 pojo，它有一个来自 javamoney 库的 CurrencyUnit 类型的字段。当我编码这个 pojo 时， jackson 抛出了一个异常。我记得当我没有定义任何默认构造函数时出现此异常。但在这种情况下，我无法维护 CurrencyUnit 类，因为它来自依赖项。我怎样才能继续这项工作？

异常(exception):

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `javax.money.CurrencyUnit` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information\n at 

Answer 1

您应该为要使用或注册已创建模块的 javax.money 包中的每种类型编写自定义序列化器/反序列化器。例如:jackson-datatype-money .

您需要添加dependency :

<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>jackson-datatype-money</artifactId>
    <version>1.3.0</version>
</dependency>

简单的使用示例:

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import org.zalando.jackson.datatype.money.MoneyModule;

import javax.money.CurrencyUnit;
import javax.money.Monetary;

public class JsonMoneyApp {

    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        mapper.enable(SerializationFeature.INDENT_OUTPUT);
        mapper.registerModule(new MoneyModule());

        CurrencyUnit cu = Monetary.getCurrency("USD");
        String json = mapper.writeValueAsString(cu);
        System.out.println(json);

        CurrencyUnit unit = mapper.readValue(json, CurrencyUnit.class);
        System.out.println(unit);
    }
}

上面的代码打印:

"USD"
USD