Jackson检测到重复的JSON POJO属性和Map键 [英] Jackson detection of duplicate JSON POJO properties and Map keys
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问题描述
我正在尝试捕获重复的POJO属性,或者Map键已经过了我的WebService。
I'm trying to catch duplicate POJO properties or Map keys are past to my WebService.
所以例如我想抛出一个错误,如果 field1
出现两次或地图键 1
出现两次:
So for instance I want to throw an error if field1
appears twice or map key 1
appears twice:
{
"field1" : 1,
"field1" : 2,
"map" : {
"1" : {
"fieldA" : "null",
"fieldB" : "2"
},
"1" : {
"fieldX" : "null",
"fieldY" : "2"
}
}
}
推荐答案
看看这个讨论: http://jackson-users.ning.com/forum/topics/detecting-duplicate-field
以下是一个示例代码对于Map类:
Here is an example code that comes out from it for a Map class:
public class JacksonDuplicates {
private static final String JSON = "{\n" +
" \"field1\" : 1,\n" +
" \"field1\" : 2,\n" +
" \"map\" : {\n" +
" \"1\" : {\n" +
" \"fieldA\" : \"null\",\n" +
" \"fieldB\" : \"2\"\n" +
" },\n" +
" \"1\" : {\n" +
" \"fieldX\" : \"null\",\n" +
" \"fieldY\" : \"2\"\n" +
" }\n" +
" }\n" +
"}";
private static class SingleKeyHashMap<K, V> extends HashMap<K, V> {
@Override
public V put(K key, V value) {
if (containsKey(key)) {
throw new IllegalArgumentException("duplicate key " + key);
}
return super.put(key, value);
}
}
public static void main(String[] args) throws IOException {
SimpleModule module = new SimpleModule();
module.addAbstractTypeMapping(Map.class, SingleKeyHashMap.class);
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(module);
mapper.readValue(JSON, Map.class);
}
}
输出:
Exception in thread "main" java.lang.IllegalArgumentException: duplicate key field1
at jackson.JacksonDuplicates$SingleKeyHashMap.put(JacksonDuplicates.java:38)
at com.fasterxml.jackson.databind.deser.std.MapDeserializer._readAndBindStringMap(MapDeserializer.java:434)
at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:312)
at com.fasterxml.jackson.databind.deser.std.MapDeserializer.deserialize(MapDeserializer.java:26)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2993)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2098)
at jackson.JacksonDuplicates.main(JacksonDuplicates.java:50)
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