package com.fasterxml.jackson.databind;

import com.fasterxml.jackson.databind.cfg.MapperConfig;
import com.fasterxml.jackson.databind.introspect.AnnotatedField;
import com.fasterxml.jackson.databind.introspect.AnnotatedMethod;
import com.fasterxml.jackson.databind.introspect.AnnotatedParameter;

Class that defines how names of JSON properties ("external names") are derived from names of POJO methods and fields ("internal names"), in cases where they are not auto-detected and no explicit annotations exist for naming. Methods are passed information about POJO member for which name is needed, as well as default name that would be used if no custom strategy was used.

Default (empty) implementation returns suggested ("default") name unmodified.

Note that the strategy is guaranteed to be called once per logical property (which may be represented by multiple members; such as pair of a getter and a setter), but may be called for each: implementations should not count on exact number of times, and should work for any member that represent a property.

In absence of a registered custom strategy, default Java property naming strategy is used, which leaves field names as is, and removes set/get/is prefix from methods (as well as lower-cases initial sequence of capitalized characters).

/** * Class that defines how names of JSON properties ("external names") * are derived from names of POJO methods and fields ("internal names"), * in cases where they are not * auto-detected and no explicit annotations exist for naming. * Methods are passed information about POJO member for which name is needed, * as well as default name that would be used if no custom strategy was used. *<p> * Default (empty) implementation returns suggested ("default") name unmodified. *<p> * Note that the strategy is guaranteed to be called once per logical property * (which may be represented by multiple members; such as pair of a getter and * a setter), but may be called for each: implementations should not count on * exact number of times, and should work for any member that represent a * property. *<p> * In absence of a registered custom strategy, default Java property naming strategy * is used, which leaves field names as is, and removes set/get/is prefix * from methods (as well as lower-cases initial sequence of capitalized * characters). */
@SuppressWarnings("serial") public class PropertyNamingStrategy // NOTE: was abstract until 2.7 implements java.io.Serializable {
Naming convention used in languages like C, where words are in lower-case letters, separated by underscores. See SnakeCaseStrategy for details.
Since:2.7 (was formerly called CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES)
/** * Naming convention used in languages like C, where words are in lower-case * letters, separated by underscores. * See {@link SnakeCaseStrategy} for details. * * @since 2.7 (was formerly called {@link #CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES}) */
public static final PropertyNamingStrategy SNAKE_CASE = new SnakeCaseStrategy();
Naming convention used in languages like Pascal, where words are capitalized and no separator is used between words. See PascalCaseStrategy for details.
Since:2.7 (was formerly called PASCAL_CASE_TO_CAMEL_CASE)
/** * Naming convention used in languages like Pascal, where words are capitalized * and no separator is used between words. * See {@link PascalCaseStrategy} for details. * * @since 2.7 (was formerly called {@link #PASCAL_CASE_TO_CAMEL_CASE}) */
public static final PropertyNamingStrategy UPPER_CAMEL_CASE = new UpperCamelCaseStrategy();
Naming convention used in Java, where words other than first are capitalized and no separator is used between words. Since this is the native Java naming convention, naming strategy will not do any transformation between names in data (JSON) and POJOS.
Since:2.7 (was formerly called PASCAL_CASE_TO_CAMEL_CASE)
/** * Naming convention used in Java, where words other than first are capitalized * and no separator is used between words. Since this is the native Java naming convention, * naming strategy will not do any transformation between names in data (JSON) and * POJOS. * * @since 2.7 (was formerly called {@link #PASCAL_CASE_TO_CAMEL_CASE}) */
public static final PropertyNamingStrategy LOWER_CAMEL_CASE = new PropertyNamingStrategy();
Naming convention in which all words of the logical name are in lower case, and no separator is used between words. See LowerCaseStrategy for details.
Since:2.4
/** * Naming convention in which all words of the logical name are in lower case, and * no separator is used between words. * See {@link LowerCaseStrategy} for details. * * @since 2.4 */
public static final PropertyNamingStrategy LOWER_CASE = new LowerCaseStrategy();
Naming convention used in languages like Lisp, where words are in lower-case letters, separated by hyphens. See KebabCaseStrategy for details.
Since:2.7
/** * Naming convention used in languages like Lisp, where words are in lower-case * letters, separated by hyphens. * See {@link KebabCaseStrategy} for details. * * @since 2.7 */
public static final PropertyNamingStrategy KEBAB_CASE = new KebabCaseStrategy(); /* /********************************************************** /* API /********************************************************** */
Method called to find external name (name used in JSON) for given logical POJO property, as defined by given field.
Params:
  • config – Configuration in used: either SerializationConfig or DeserializationConfig, depending on whether method is called during serialization or deserialization
  • field – Field used to access property
  • defaultName – Default name that would be used for property in absence of custom strategy
Returns:Logical name to use for property that the field represents
/** * Method called to find external name (name used in JSON) for given logical * POJO property, * as defined by given field. * * @param config Configuration in used: either <code>SerializationConfig</code> * or <code>DeserializationConfig</code>, depending on whether method is called * during serialization or deserialization * @param field Field used to access property * @param defaultName Default name that would be used for property in absence of custom strategy * * @return Logical name to use for property that the field represents */
public String nameForField(MapperConfig<?> config, AnnotatedField field, String defaultName) { return defaultName; }
Method called to find external name (name used in JSON) for given logical POJO property, as defined by given getter method; typically called when building a serializer. (but not always -- when using "getter-as-setter", may be called during deserialization)
Params:
  • config – Configuration in used: either SerializationConfig or DeserializationConfig, depending on whether method is called during serialization or deserialization
  • method – Method used to access property.
  • defaultName – Default name that would be used for property in absence of custom strategy
Returns:Logical name to use for property that the method represents
/** * Method called to find external name (name used in JSON) for given logical * POJO property, * as defined by given getter method; typically called when building a serializer. * (but not always -- when using "getter-as-setter", may be called during * deserialization) * * @param config Configuration in used: either <code>SerializationConfig</code> * or <code>DeserializationConfig</code>, depending on whether method is called * during serialization or deserialization * @param method Method used to access property. * @param defaultName Default name that would be used for property in absence of custom strategy * * @return Logical name to use for property that the method represents */
public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName) { return defaultName; }
Method called to find external name (name used in JSON) for given logical POJO property, as defined by given setter method; typically called when building a deserializer (but not necessarily only then).
Params:
  • config – Configuration in used: either SerializationConfig or DeserializationConfig, depending on whether method is called during serialization or deserialization
  • method – Method used to access property.
  • defaultName – Default name that would be used for property in absence of custom strategy
Returns:Logical name to use for property that the method represents
/** * Method called to find external name (name used in JSON) for given logical * POJO property, * as defined by given setter method; typically called when building a deserializer * (but not necessarily only then). * * @param config Configuration in used: either <code>SerializationConfig</code> * or <code>DeserializationConfig</code>, depending on whether method is called * during serialization or deserialization * @param method Method used to access property. * @param defaultName Default name that would be used for property in absence of custom strategy * * @return Logical name to use for property that the method represents */
public String nameForSetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName) { return defaultName; }
Method called to find external name (name used in JSON) for given logical POJO property, as defined by given constructor parameter; typically called when building a deserializer (but not necessarily only then).
Params:
  • config – Configuration in used: either SerializationConfig or DeserializationConfig, depending on whether method is called during serialization or deserialization
  • ctorParam – Constructor parameter used to pass property.
  • defaultName – Default name that would be used for property in absence of custom strategy
/** * Method called to find external name (name used in JSON) for given logical * POJO property, * as defined by given constructor parameter; typically called when building a deserializer * (but not necessarily only then). * * @param config Configuration in used: either <code>SerializationConfig</code> * or <code>DeserializationConfig</code>, depending on whether method is called * during serialization or deserialization * @param ctorParam Constructor parameter used to pass property. * @param defaultName Default name that would be used for property in absence of custom strategy */
public String nameForConstructorParameter(MapperConfig<?> config, AnnotatedParameter ctorParam, String defaultName) { return defaultName; } /* /********************************************************** /* Public base class for simple implementations /********************************************************** */ public static abstract class PropertyNamingStrategyBase extends PropertyNamingStrategy { @Override public String nameForField(MapperConfig<?> config, AnnotatedField field, String defaultName) { return translate(defaultName); } @Override public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName) { return translate(defaultName); } @Override public String nameForSetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName) { return translate(defaultName); } @Override public String nameForConstructorParameter(MapperConfig<?> config, AnnotatedParameter ctorParam, String defaultName) { return translate(defaultName); } public abstract String translate(String propertyName); } /* /********************************************************** /* Standard implementations /********************************************************** */
A PropertyNamingStrategy that translates typical camel case Java property names to lower case JSON element names, separated by underscores. This implementation is somewhat lenient, in that it provides some additional translations beyond strictly translating from camel case only. In particular, the following translations are applied by this PropertyNamingStrategy.
  • Every upper case letter in the Java property name is translated into two characters, an underscore and the lower case equivalent of the target character, with three exceptions.
    1. For contiguous sequences of upper case letters, characters after the first character are replaced only by their lower case equivalent, and are not preceded by an underscore.
      • This provides for reasonable translations of upper case acronyms, e.g., "theWWW" is translated to "the_www".
    2. An upper case character in the first position of the Java property name is not preceded by an underscore character, and is translated only to its lower case equivalent.
      • For example, "Results" is translated to "results", and not to "_results".
    3. An upper case character in the Java property name that is already preceded by an underscore character is translated only to its lower case equivalent, and is not preceded by an additional underscore.
      • For example, "user_Name" is translated to "user_name", and not to "user__name" (with two underscore characters).
  • If the Java property name starts with an underscore, then that underscore is not included in the translated name, unless the Java property name is just one character in length, i.e., it is the underscore character. This applies only to the first character of the Java property name.
These rules result in the following additional example translations from Java property names to JSON element names.
  • "userName" is translated to "user_name"
  • "UserName" is translated to "user_name"
  • "USER_NAME" is translated to "user_name"
  • "user_name" is translated to "user_name" (unchanged)
  • "user" is translated to "user" (unchanged)
  • "User" is translated to "user"
  • "USER" is translated to "user"
  • "_user" is translated to "user"
  • "_User" is translated to "user"
  • "__user" is translated to "_user" (the first of two underscores was removed)
  • "user__name" is translated to "user__name" (unchanged, with two underscores)
Since:2.7 (was previously called }
/** * A {@link PropertyNamingStrategy} that translates typical camel case Java * property names to lower case JSON element names, separated by * underscores. This implementation is somewhat lenient, in that it * provides some additional translations beyond strictly translating from * camel case only. In particular, the following translations are applied * by this PropertyNamingStrategy. * * <ul><li>Every upper case letter in the Java property name is translated * into two characters, an underscore and the lower case equivalent of the * target character, with three exceptions. * <ol><li>For contiguous sequences of upper case letters, characters after * the first character are replaced only by their lower case equivalent, * and are not preceded by an underscore. * <ul><li>This provides for reasonable translations of upper case acronyms, * e.g., &quot;theWWW&quot; is translated to &quot;the_www&quot;.</li></ul></li> * <li>An upper case character in the first position of the Java property * name is not preceded by an underscore character, and is translated only * to its lower case equivalent. * <ul><li>For example, &quot;Results&quot; is translated to &quot;results&quot;, * and not to &quot;_results&quot;.</li></ul></li> * <li>An upper case character in the Java property name that is already * preceded by an underscore character is translated only to its lower case * equivalent, and is not preceded by an additional underscore. * <ul><li>For example, &quot;user_Name&quot; is translated to * &quot;user_name&quot;, and not to &quot;user__name&quot; (with two * underscore characters).</li></ul></li></ol></li> * <li>If the Java property name starts with an underscore, then that * underscore is not included in the translated name, unless the Java * property name is just one character in length, i.e., it is the * underscore character. This applies only to the first character of the * Java property name.</li></ul> * * These rules result in the following additional example translations from * Java property names to JSON element names. * <ul><li>&quot;userName&quot; is translated to &quot;user_name&quot;</li> * <li>&quot;UserName&quot; is translated to &quot;user_name&quot;</li> * <li>&quot;USER_NAME&quot; is translated to &quot;user_name&quot;</li> * <li>&quot;user_name&quot; is translated to &quot;user_name&quot; (unchanged)</li> * <li>&quot;user&quot; is translated to &quot;user&quot; (unchanged)</li> * <li>&quot;User&quot; is translated to &quot;user&quot;</li> * <li>&quot;USER&quot; is translated to &quot;user&quot;</li> * <li>&quot;_user&quot; is translated to &quot;user&quot;</li> * <li>&quot;_User&quot; is translated to &quot;user&quot;</li> * <li>&quot;__user&quot; is translated to &quot;_user&quot; * (the first of two underscores was removed)</li> * <li>&quot;user__name&quot; is translated to &quot;user__name&quot; * (unchanged, with two underscores)</li></ul> * * @since 2.7 (was previously called } */
public static class SnakeCaseStrategy extends PropertyNamingStrategyBase { @Override public String translate(String input) { if (input == null) return input; // garbage in, garbage out int length = input.length(); StringBuilder result = new StringBuilder(length * 2); int resultLength = 0; boolean wasPrevTranslated = false; for (int i = 0; i < length; i++) { char c = input.charAt(i); if (i > 0 || c != '_') // skip first starting underscore { if (Character.isUpperCase(c)) { if (!wasPrevTranslated && resultLength > 0 && result.charAt(resultLength - 1) != '_') { result.append('_'); resultLength++; } c = Character.toLowerCase(c); wasPrevTranslated = true; } else { wasPrevTranslated = false; } result.append(c); resultLength++; } } return resultLength > 0 ? result.toString() : input; } }
A PropertyNamingStrategy that translates typical camelCase Java property names to PascalCase JSON element names (i.e., with a capital first letter). In particular, the following translations are applied by this PropertyNamingStrategy.
  • The first lower-case letter in the Java property name is translated into its equivalent upper-case representation.
This rules result in the following example translation from Java property names to JSON element names.
  • "userName" is translated to "UserName"
Since:2.7 (was formerly called PascalCaseStrategy)
/** * A {@link PropertyNamingStrategy} that translates typical camelCase Java * property names to PascalCase JSON element names (i.e., with a capital * first letter). In particular, the following translations are applied by * this PropertyNamingStrategy. * * <ul><li>The first lower-case letter in the Java property name is translated * into its equivalent upper-case representation.</li></ul> * * This rules result in the following example translation from * Java property names to JSON element names. * <ul><li>&quot;userName&quot; is translated to &quot;UserName&quot;</li></ul> * * @since 2.7 (was formerly called {@link PascalCaseStrategy}) */
public static class UpperCamelCaseStrategy extends PropertyNamingStrategyBase {
Converts camelCase to PascalCase For example, "userName" would be converted to "UserName".
Params:
  • input – formatted as camelCase string
Returns:input converted to PascalCase format
/** * Converts camelCase to PascalCase * * For example, "userName" would be converted to * "UserName". * * @param input formatted as camelCase string * @return input converted to PascalCase format */
@Override public String translate(String input) { if (input == null || input.length() == 0){ return input; // garbage in, garbage out } // Replace first lower-case letter with upper-case equivalent char c = input.charAt(0); char uc = Character.toUpperCase(c); if (c == uc) { return input; } StringBuilder sb = new StringBuilder(input); sb.setCharAt(0, uc); return sb.toString(); } }
Simple strategy where external name simply only uses lower-case characters, and no separators. Conversion from internal name like "someOtherValue" would be into external name if "someothervalue".
Since:2.4
/** * Simple strategy where external name simply only uses lower-case characters, * and no separators. * Conversion from internal name like "someOtherValue" would be into external name * if "someothervalue". * * @since 2.4 */
public static class LowerCaseStrategy extends PropertyNamingStrategyBase { @Override public String translate(String input) { return input.toLowerCase(); } }
Naming strategy similar to SnakeCaseStrategy, but instead of underscores as separators, uses hyphens. Naming convention traditionally used for languages like Lisp.
Since:2.7
/** * Naming strategy similar to {@link SnakeCaseStrategy}, but instead of underscores * as separators, uses hyphens. Naming convention traditionally used for languages * like Lisp. * * @since 2.7 */
public static class KebabCaseStrategy extends PropertyNamingStrategyBase { @Override public String translate(String input) { if (input == null) return input; // garbage in, garbage out int length = input.length(); if (length == 0) { return input; } StringBuilder result = new StringBuilder(length + (length >> 1)); int upperCount = 0; for (int i = 0; i < length; ++i) { char ch = input.charAt(i); char lc = Character.toLowerCase(ch); if (lc == ch) { // lower-case letter means we can get new word // but need to check for multi-letter upper-case (acronym), where assumption // is that the last upper-case char is start of a new word if (upperCount > 1) { // so insert hyphen before the last character now result.insert(result.length() - 1, '-'); } upperCount = 0; } else { // Otherwise starts new word, unless beginning of string if ((upperCount == 0) && (i > 0)) { result.append('-'); } ++upperCount; } result.append(lc); } return result.toString(); } } /* /********************************************************** /* Deprecated variants, aliases /********************************************************** */
Deprecated:Since 2.7 use SNAKE_CASE instead;
/** * @deprecated Since 2.7 use {@link #SNAKE_CASE} instead; */
@Deprecated // since 2.7 public static final PropertyNamingStrategy CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES = SNAKE_CASE;
Deprecated:Since 2.7 use UPPER_CAMEL_CASE instead;
/** * @deprecated Since 2.7 use {@link #UPPER_CAMEL_CASE} instead; */
@Deprecated // since 2.7 public static final PropertyNamingStrategy PASCAL_CASE_TO_CAMEL_CASE = UPPER_CAMEL_CASE;
Deprecated:In 2.7 use SnakeCaseStrategy instead
/** * @deprecated In 2.7 use {@link SnakeCaseStrategy} instead */
@Deprecated public static class LowerCaseWithUnderscoresStrategy extends SnakeCaseStrategy {}
Deprecated:In 2.7 use UpperCamelCaseStrategy instead
/** * @deprecated In 2.7 use {@link UpperCamelCaseStrategy} instead */
@Deprecated public static class PascalCaseStrategy extends UpperCamelCaseStrategy {} }