杰克逊xml反序列化内联数组 [英] jackson xml deserialize inline array
问题描述
如何反序列化这种奇怪的XML.在我看来,缺少道具实体(在道具周围),但是我无法更改此XML(Web服务)的来源.
How to deserialize such strange XML. In my opinion, the props-entity is missing (around the props), but I can't change the source of this XML (a web service).
<parents>
<parent name="first">
<description><![CDATA[Description for the first-Entity]]></description>
<prop name="level">
<value><![CDATA[1]]></value>
</prop>
<prop name="enabled">
<value><![CDATA[true]]></value>
</prop>
<prop name="version">
<value><![CDATA[1.0-beta3]]></value>
</prop>
</parent>
<parent name="second">...</parent>
...
</parents>
我的实体是
public class Test {
@Test
public void deserializerTest() throws JsonParseException, JsonMappingException, IOException {
ObjectMapper om = new XmlMapper();
List<Parent> xml = om.readValue(new File("./test.xml"),
new TypeReference<List<Parent>>() {});
}
}
public class Prop {
@JacksonXmlProperty(isAttribute = true)
public String name;
@JacksonXmlText
public String value;
}
@JacksonXmlRootElement
public class Parent {
@JacksonXmlProperty(isAttribute = true)
public String name;
public String description;
// 1. alternative with List
public List<Prop> prop;
// 2. alternative with Map
@JsonDeserialize(using = PropDeser.class)
public Map<String, String> prop;
}
public static class PropDeser extends JsonDeserializer<Map<String, String>> {
@Override
public Map<String, String> deserialize(JsonParser jp,
DeserializationContext ctxt) throws IOException,
JsonProcessingException {
Map<String, String> ret = new HashMap<String, String>();
boolean eof = false;
while (jp.hasCurrentToken()) {
JsonToken t = jp.getCurrentToken();
switch (t) {
case END_OBJECT:
if (eof) {
return ret;
}
eof = true;
break;
case VALUE_STRING:
ret.put(jp.getCurrentName(), jp.getText());
break;
default:
eof = false;
break;
}
jp.nextValue();
}
return null;
}
}
1.替代
创建一个异常'无法实例化JSON字符串中的类型[简单类型,类my.test.Prop]的值;没有单字符串构造函数/工厂方法(通过引用链:my.test.Parent ["prop"])'
1. Alternative
creates an exception 'Can not instantiate value of type [simple type, class my.test.Prop] from JSON String; no single-String constructor/factory method (through reference chain: my.test.Parent["prop"])'
我不想要一个简单字符串列表.我需要:名字和价值.因此我想到了通过创建自己的解串器来使用Map<String, String>
的想法...
I don't want a simple-String list. I need both: name and value. So I came to the idea of using a Map<String, String>
by creating my own deserializer...
错误似乎是方法PropDeser.deserialize()消耗了父项的关闭标记.
The error seems to be method PropDeser.deserialize() consumes the closing-tag of the parent.
java.lang.NullPointerException
at com.fasterxml.jackson.databind.deser.impl.BeanPropertyMap.find(BeanPropertyMap.java:160)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:287)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:112)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:226)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:203)
at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:23)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2575)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:1766)
at my.test.Test.deserializerTest(Test.java:57)
是否有可能在 XML流中向后迭代?该方法如何知道何时停止?我不知道.
Is there a possibility to iterate backward in the XML-stream? How can the method know when to stop? I have no clue.
推荐答案
应该可以使用@JacksonXmlElementWrapper(useWrapping=false)
的Jackson XML模块2.1处理列表元素的未包装"样式.
It should be possible to handle "unwrapped" style of list elements with Jackson XML module 2.1, with @JacksonXmlElementWrapper(useWrapping=false)
.
结构应如下所示:
@JacksonXmlRootElement(localName="parents")
public class Parents {
@JacksonXmlElementWrapper(useWrapping=false)
public List<Parent> parent;
}
public class Parent {
@JacksonXmlProperty(isAttribute=true)
public String name;
public String description;
@JacksonXmlElementWrapper(useWrapping=false)
public List<Prop> prop;
}
public class Prop {
@JacksonXmlProperty(isAttribute=true)
public String name;
public String value;
}
所以您的解决方案非常接近.
so your solution was quite close.
请注意,如果使用内部类,则它们在声明中需要具有静态". 我用2.1.4进行了测试,它对我有用.
Note that if inner classes are used, they need to have 'static' in declaration. I tested this with 2.1.4, and it works for me.
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