字段驼峰转换

前言

属性驼峰转换主要有三种配置形式：针对全局配置、针对具体类配置以及针对具体属性配置。他们生效的优先级顺序以此是：属性 > 类 > 全局。

先定义一个示例类，用于之后说明：

@Getter
@Setter
public class Author {

    private String username;

    private String idCard;

    private String mobilePhone;

}

全局配置

全局配置借助 com.fasterxml.jackson.databind.PropertyNamingStrategy实现：

public class PropertyNamingStrategy // NOTE: was abstract until 2.7
    implements java.io.Serializable
{
    /**
     * 示例: id_card
     */
    public static final PropertyNamingStrategy SNAKE_CASE = new SnakeCaseStrategy();

    /**
     * 示例: IdCard
     */
    public static final PropertyNamingStrategy UPPER_CAMEL_CASE = new UpperCamelCaseStrategy();

    /**
     * 示例: idCard
     */
    public static final PropertyNamingStrategy LOWER_CAMEL_CASE = new PropertyNamingStrategy();

    /**
     * 示例: idcard
     */
    public static final PropertyNamingStrategy LOWER_CASE = new LowerCaseStrategy();

    /**
     * 示例: id-card
     */
    public static final PropertyNamingStrategy KEBAB_CASE = new KebabCaseStrategy();
}

我们只需要使用 ObjectMapper.setPropertyNamingStrategy即可：

public static void main(String[] args) throws JsonProcessingException {
    Author author = new Author();
    author.setUsername("张三");
    author.setIdCard("31000000000000");
    author.setMobilePhone("13500000000")

    ObjectMapper mapper = new ObjectMapper()

    mapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
    System.out.println("SNAKE_CASE:");
    System.out.println(mapper.writeValueAsString(author));

    mapper.setPropertyNamingStrategy(PropertyNamingStrategy.UPPER_CAMEL_CASE);
    System.out.println("UPPER_CAMEL_CASE:");
    System.out.println(mapper.writeValueAsString(author));

    mapper.setPropertyNamingStrategy(PropertyNamingStrategy.LOWER_CAMEL_CASE);
    System.out.println("LOWER_CAMEL_CASE:");
    System.out.println(mapper.writeValueAsString(author));

    mapper.setPropertyNamingStrategy(PropertyNamingStrategy.LOWER_CASE);
    System.out.println("LOWER_CASE:");
    System.out.println(mapper.writeValueAsString(author));

    mapper.setPropertyNamingStrategy(PropertyNamingStrategy.KEBAB_CASE);
    System.out.println("KEBAB_CASE:");
    System.out.println(mapper.writeValueAsString(author));
}

输出示例：

SNAKE_CASE:
{"username":"张三","id_card":"31000000000000","mobile_phone":"13500000000"}

UPPER_CAMEL_CASE:
{"Username":"张三","IdCard":"31000000000000","MobilePhone":"13500000000"}

LOWER_CAMEL_CASE:
{"username":"张三","idCard":"31000000000000","mobilePhone":"13500000000"}

LOWER_CASE:
{"username":"张三","idcard":"31000000000000","mobilephone":"13500000000"}

KEBAB_CASE:
{"username":"张三","id-card":"31000000000000","mobile-phone":"13500000000"}

针对具体类配置

针对类的配置同样是借助于 com.fasterxml.jackson.databind.PropertyNamingStrategy。区别是需要在类上使用 @JsonNaming注解：

@JsonNaming(PropertyNamingStrategy.KebabCaseStrategy.class)
//@JsonNaming(PropertyNamingStrategy.UpperCamelCaseStrategy.class)
//@JsonNaming(PropertyNamingStrategy.LowerCaseStrategy.class)
//@JsonNaming(PropertyNamingStrategy.KebabCaseStrategy.class)
// ...
public class Author {

}

public static void main(String[] args) throws JsonProcessingException {
    Author author = new Author();
    author.setUsername("张三");
    author.setIdCard("31000000000000");
    author.setMobilePhone("13500000000")

    ObjectMapper mapper = new ObjectMapper()

    // 优先级小于 @JsonNaming, 这里不会生效
    mapper.setPropertyNamingStrategy(PropertyNamingStrategy.UPPER_CAMEL_CASE);

    System.out.println(mapper.writeValueAsString(author));
}

针对具体属性

@Getter
@Setter
@JsonNaming(PropertyNamingStrategy.UpperCamelCaseStrategy.class) // 优先级顺序小于 @JsonProperty
public class Author {

    private String username; // @JsonNaming 只会针对该属性生效

    @JsonProperty("id_card")
    private String idCard;

    @JsonProperty("mobile-phone")
    private String mobilePhone;
}


public static void main(String[] args) throws JsonProcessingException {
    Author author = new Author();
    author.setUsername("张三");
    author.setIdCard("31000000000000");
    author.setMobilePhone("13500000000");
    ObjectMapper mapper = new ObjectMapper();

    // 优先级小于 @JsonNaming, 这里不会生效
    mapper.setPropertyNamingStrategy(PropertyNamingStrategy.KEBAB_CASE);

    System.out.println(mapper.writeValueAsString(author));
}

输出示例：

{"Username":"张三","id_card":"31000000000000","mobile-phone":"13500000000"}