Java jackson:将json的一些字段映射到类的内部字段
我想将json的一些字段映射到类的内部字段。e、 gJava jackson:将json的一些字段映射到类的内部字段,java,json,jackson,Java,Json,Jackson,我想将json的一些字段映射到类的内部字段。e、 g { values:[{ "name":"Abc", "age":18, "street":"test", "postalcoad":"1231412" }, { "name":"ccvb", "age":20, "street":"test2", "postalcoad":"123" } ]} 下面是我的java类 @JsonIgnoreProperties(ignoreUnknown = true) publ
{
values:[{
"name":"Abc",
"age":18,
"street":"test",
"postalcoad":"1231412"
},
{
"name":"ccvb",
"age":20,
"street":"test2",
"postalcoad":"123"
}
]}
下面是我的java类
@JsonIgnoreProperties(ignoreUnknown = true)
public class Customer{
@JsonProperty("name")
private string name;
@JsonProperty("age")
private int age;
private Address address;
}
@JsonIgnoreProperties(ignoreUnknown = true)
public class Address{
@JsonProperty("street")
private string street;
@JsonProperty("postalcode")
private string postalcode;
}
ObjectMapper mapper = new ObjectMapper();
Customer[] c = mapper.readValue(mapper.readTree(json).get("values").toString(), Customer[].class);
它返回没有地址的客户对象。知道如何从这个json创建Address对象吗 选项之一是使用
@JsonCreator
注释:
@JsonCreator
public Customer(
@JsonProperty("name") String name,
@JsonProperty("age") int age,
@JsonProperty("street") String street,
@JsonProperty("postalcode") String postalcode
) {
this.name = name;
this.age = age;
this.address = new Address();
this.address.street = street;
this.address.postalcode = postalcode;
}
第二个选项是创建自定义反序列化程序,并使用@JsonDeserialize
注释将类与反序列化程序绑定
@JsonDeserialize(using = CustomerDeserializer.class)
public static class Customer{
....
}
public class CustomerDeserializer extends StdDeserializer<Customer> {
public CustomerDeserializer() {
super(Customer.class);
}
@Override
public Customer deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JsonProcessingException {
Customer customer = new Customer();
JsonNode treeNode = p.readValueAsTree();
if (treeNode == null) {
return null;
}
customer.setName(treeNode.get("name").asText());
customer.setAge(treeNode.get("age").asInt());
Address address = new Address();
address.setStreet(treeNode.get("street").asText());
address.setPostalcode(treeNode.get("postalcode").asText());
customer.setAddress(address);
return customer;
}
}
我将创建一个自定义反序列化程序,并在其中调用Customer的默认反序列化程序,然后调用Address的默认反序列化程序。然后将地址添加到customer对象。这样,它们看起来都是同一个json,但是您可以得到两个不同的对象,并且可以按照您想要的方式连接它们
要从自定义反序列化器调用标准反序列化器,请参见以下答案:。您可能可以通过这种方式获得一些见解,我必须通过构造函数初始化所有字段。事实上我是在逃避。有100多个字段,其中大多数都使用自定义反序列化程序。这听起来很可怕!:)祝你好运。有没有一种方法可以在Customer类的address字段上使用@JsonDeserialize。实际上有很多字段(大约100个),它们使用自定义反序列化程序,所以如果我在类上放置@jsondeselliate,那么我必须更改每个字段的逻辑。@Ahmad.Masood我不这么认为,因为在
json
中没有一个适合地址的合适字段,所以jackson在反序列化阶段跳过了你的地址
字段。你的回答对我帮助很大:)@JSONANYSETER做了这个把戏。
public interface PostConstruct {
void postConstruct();
}
public class Customer implements PostConstruct {
//mapping
private Map<String, Object> additionalFields = new HashMap<>();
@JsonAnySetter
public void setAdditionalValue(String key, Object value) {
additionalFields.put(key, value);
}
@Override
public void postConstruct() {
address = new Address();
address.setStreet(String.valueOf(additionalFields.get("street")));
address.setPostalcode(String.valueOf(additionalFields.get("postalcode")));
}
}
public static class PostConstructDeserializer extends DelegatingDeserializer {
private final JsonDeserializer<?> deserializer;
public PostConstructDeserializer(JsonDeserializer<?> deserializer) {
super(deserializer);
this.deserializer = deserializer;
}
@Override
protected JsonDeserializer<?> newDelegatingInstance(JsonDeserializer<?> newDelegatee) {
return deserializer;
}
@Override
public Object deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
Object result = _delegatee.deserialize(jp, ctxt);
if (result instanceof PostConstruct) {
((PostConstruct) result).postConstruct();
}
return result;
}
}
//using of post construct deserializer
ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.setDeserializerModifier(new BeanDeserializerModifier() {
@Override
public JsonDeserializer<?> modifyDeserializer(DeserializationConfig config,
BeanDescription beanDesc,
final JsonDeserializer<?> deserializer) {
return new PostConstructDeserializer(deserializer);
}
});
mapper.registerModule(module);