Jackson xml空元素序列化 [英] Jackson xml empty element serialization

问题描述

我很难用这个。 Jackson 2.2 XML序列化器似乎以这种方式序列化空对象字段：

I'm having a hard time with this one. Jackson 2.2 XML serializer seems to serialize empty object fields this way:

<field/>

如何强制它序列化这样的空字段：

How can I force it to serialize such empty field like this:

<field></field>

非常感谢您的时间和答案。

Thank you very much for your time and answers.

推荐答案

请看这个问题：如何覆盖Jackson 2.0中的null序列化程序？。对于 XmlMapper ，它可能如下所示。创建 NullSerializer ：

Please, see this question: How do you override the null serializer in Jackson 2.0?. For XmlMapper it could look like below. Create NullSerializer:

class NullSerializer extends JsonSerializer<Object> {

    @Override
    public void serialize(Object value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {
        jgen.writeString("");
    }
}

和简单用法：

XmlSerializerProvider provider = new XmlSerializerProvider(new XmlRootNameLookup());
provider.setNullValueSerializer(new NullSerializer());

XmlMapper xmlMapper = new XmlMapper();
xmlMapper.setSerializerProvider(provider);

System.out.println(xmlMapper.writeValueAsString(new Entity()));

以上程序打印：

<Entity xmlns=""><field></field></Entity>

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