用
JsonParser.Feature.STRICT_DUPLICATE_DETECTION
ObjectMapper mapper = new ObjectMapper();mapper.enable(JsonParser.Feature.STRICT_DUPLICATE_DETECTION);MyPOJO result = mapper.readValue(json, MyPOJO.class);
结果是：
Exception in thread "main" com.fasterxml.jackson.core.JsonParseException: Duplicate field 'email'
您也可以尝试使用
DeserializationFeature.FAIL_ON_READING_DUP_TREE_KEY（更多信息）如果先将json字符串/输入反序列化为jackson
json树，然后反序列化为POJO，则会触发该问题。可以将其与自定义结合起来，
JsonDeserializer如下所示：
private static class MyPojoDeserializer extends JsonDeserializer<MyPOJO>{ @Override public MyPOJO deserialize(JsonParser p, DeserializationContext ctxt) throws IOException{ JsonNode tree = p.readValueAsTree(); return p.getCodec().treeToValue(tree, MyPOJO.class); }}设置一次，并使用与以前相同的方式：
// setup ObjectMapper ObjectMapper mapper = new ObjectMapper();mapper.enable(DeserializationFeature.FAIL_ON_READING_DUP_TREE_KEY);SimpleModule module = new SimpleModule();module.addDeserializer(MyPOJO.class,new MyPojoDeserializer() );mapper.registerModule(module);// usemapper.readValue(json, MyPOJO.class);
结果：
Exception in thread "main" com.fasterxml.jackson.databind.JsonMappingException: Duplicate field 'email' for ObjectNode: not allowed when FAIL_ON_READING_DUP_TREE_KEY enabled
其他选择是自己在自定义反序列化器中或在POJO setter方法中实现所有逻辑。
