使用Jackson将带有下划线的JSON反序列化为Java中的驼峰案例？ [英] Deserialising JSON with underscores to camel case in Java using Jackson?

问题描述

要使用下划线将具有camel case属性的java对象序列化为json，我们使用 PropertyNamingStrategy 作为 SNAKE_CASE 。

To serialize java objects with camel case attributes to json with underscore we use PropertyNamingStrategy as SNAKE_CASE.

那么，是否还有相反的事情要做。也就是说，使用下划线将json反序列化为带有驼峰的Java对象。

So, is there something to do the opposite as well. That is, deserialise json with underscore to Java objects with camel case.

例如，
JSON：

For example, JSON:

{
    "user_id": "213sdadl"
    "channel_id": "asd213l"
}

应反序列化为此Java对象：

should be deserialised to this Java object:

public class User {
    String userId; // should have value "213sdadl"
    String channelId; // should have value "asd213l"
}

我知道一种方法，这是通过 @JsonProperty 注释，适用于现场级别。我有兴趣了解任何全局设置。

I know one way of doing this which is via @JsonProperty annotation which works at field level. I am interested in knowing any global setting for this.

推荐答案

您可以拥有PropertyNamingStrategy的实现，如下所示：

Well you can have an implementation for PropertyNamingStrategy that looks something like this:

import org.codehaus.jackson.map.MapperConfig;
import org.codehaus.jackson.map.PropertyNamingStrategy;
import org.codehaus.jackson.map.introspect.AnnotatedField;
import org.codehaus.jackson.map.introspect.AnnotatedMethod;

public class CustomNameStrategy extends PropertyNamingStrategy
 {
  @Override
  public String nameForField(MapperConfig
                       config,
   AnnotatedField field, String defaultName) {
     return convert(defaultName);

  }
  @Override
  public String nameForGetterMethod(MapperConfig
                       config,
   AnnotatedMethod method, String defaultName) {
     return convert(defaultName);
  }

  @Override
  public String nameForSetterMethod(MapperConfig
                       config,
    AnnotatedMethod method, String defaultName) {
   String a = convert(defaultName); 
   return a;
  }

  public String convert(String defaultName )
  {
   char[] arr = defaultName.toCharArray();
   StringBuilder nameToReturn = new StringBuilder();

   for(int i=0; i< arr.length(); i++){
      if(arr[i] == '_'){
        nameToReturn.append(Character.toUpperCase(arr[i+1]));
        i++;
      }else{
        nameToReturn.append(arr[i]);
      }
   }
   return nameToReturn.toString();
  }

 }

然后在您的实施或课程中你可以进行反序列化：

then in your implementation or the class that does the desrialization you can have:

ObjectMapper mapper = new ObjectMapper();
mapper.setPropertyNamingStrategy(new CustomNameStrategy());
YourClass yourClass = mapper.readValue(yourJsonString, YourClass.class);

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