如何为 Json 对象使用动态属性名称 [英] How to use dynamic property names for a Json object
问题描述
我们如何使 JSON 属性名称动态化.例如
How can we make the JSON property name dynamic. For example
public class Value {
@JsonProperty(value = "value")
private String val;
public void setVal(String val) {
this.val = val;
}
public String getVal() {
return val;
}
}
当序列化这个对象时,它被保存为 {"value": "actual_value_saved"}
但我想让密钥也像 {"new_key": "actual_value_saved"} 一样动态代码>.非常感谢任何帮助.
when serializing this object it's saved as {"value": "actual_value_saved"}
but I want to make the key also dynamic like {"new_key": "actual_value_saved"}
. Any help is much appreciated.
推荐答案
您可以使用 JsonAnySetter JsonAnyGetter 注释.后面你可以使用 Map
实例.如果你总是 one-key-object
你可以使用 Collections.singletonMap
在其他情况下使用 HashMap
或其他实现.下面的例子展示了使用这种方法和创建任意数量的随机 key
-s 是多么容易:
You can use JsonAnySetter JsonAnyGetter annotations. Behind you can use Map
instance. In case you have always one-key-object
you can use Collections.singletonMap
in other case use HashMap
or other implementation. Below example shows how easy you can use this approach and create as many random key
-s as you want:
import com.fasterxml.jackson.annotation.JsonAnyGetter;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.Collections;
import java.util.Map;
import java.util.Objects;
public class JsonApp {
public static void main(String[] args) throws Exception {
DynamicJsonsFactory factory = new DynamicJsonsFactory();
ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.writeValueAsString(factory.createUser("Vika")));
System.out.println(mapper.writeValueAsString(factory.createPhone("123-456-78-9")));
System.out.println(mapper.writeValueAsString(factory.any("val", "VAL!")));
}
}
class Value {
private Map<String, String> values;
@JsonAnySetter
public void put(String key, String value) {
values = Collections.singletonMap(key, value);
}
@JsonAnyGetter
public Map<String, String> getValues() {
return values;
}
@Override
public String toString() {
return values.toString();
}
}
class DynamicJsonsFactory {
public Value createUser(String name) {
return any("name", name);
}
public Value createPhone(String number) {
return any("phone", number);
}
public Value any(String key, String value) {
Value v = new Value();
v.put(Objects.requireNonNull(key), Objects.requireNonNull(value));
return v;
}
}
以上代码打印:
{"name":"Vika"}
{"phone":"123-456-78-9"}
{"val":"VAL!"}
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