Question

我正在使用遗留系统，其中数据基本上保存为非规范化格式。最糟糕的是，没有使用一致的命名策略。取下面的对象基本上包含两个地址（但可能更多）：

{
   "studentAddress": "123 new Street",
   "studentCity": "New City",
   "studentState_w": "NY",
   "studentZip": "11220",
   "teacherAddress:: "424 main st",
   "teacherCity_txt": "Summerville",
   "teacherState_x" : "NJ",
   "teacherZip": "13454",
   ...
   ...
}

我希望能够序列化/反序列化为以下对象：

public class SomeData {    
    Address teacher;
    Address student;

    public static class Address {
       String address;
       String city;
       String state;
       String zipcode;
    }
}

我的想法是像这样创建一个自定义注释AddressMapper

public @interface AddressMapper {
    String addressField () default "address",
    String cityField () default "city",
    String stateField () default "state",
    String zipField () default "zipcode"
}

然后在类上使用它：

public class SomeData {
    @AddressMapper (addressField="teacherAddress", cityField="teacherCity_txt", stateField="studentState_w", zipField="teacherZip")    
    @JsonSerialize(using = AddressSerializer.class)
    Address teacher;
    @AddressMapper (addressField="studentAddress", cityField="studentCity", stateField="studentState_w", zipField="studentZip")   
    @JsonSerialize(using = AddressSerializer.class)
    Address student; 
}

但是，我找不到从序列化方法获取@AddressMapper注释的方法

public class AddressMapper extends JsonSerializer<Address> {
    public void serialize(Address value, JsonGenerator jgen, SerializerProvider provider) {
        //How to i get field annotation????
    }
}

如何在此处获取字段注释的实例？还有另一种方法可以解决这个问题吗？

Answer 1

实现此目的的方法是实现ContextualDeserializer来读取注释。在jackson的测试用例中可以找到一个例子： https://github.com/FasterXML/jackson-databind/blob/master/src/test/java/com/fasterxml/jackson/databind/contextual/TestContextualSerialization.java

然而，反序列化对象将具有挑战性。

Answer 2

基本上你需要实现ContextualSerializer

  @Override
public JsonSerializer<?> createContextual(final SerializerProvider prov, final BeanProperty property) throws JsonMappingException {
    String[] field = null;
    JsonAlias ann = null;
    if (property != null) {
        ann = property.getAnnotation(JsonAlias.class);
    }
    if (ann != null) {
        field = ann.value();
    }
    return new JsoinAliasSerializer(field);
}

从自定义序列化程序访问字段注释

2 个答案: