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Explore the source code of the class FieldNamingPolicy.java

/*
 * Copyright (C) 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.gson;

import java.lang.reflect.Field;
import java.util.Locale;

/**
 * An enumeration that defines a few standard naming conventions for JSON field names.
 * This enumeration should be used in conjunction with {@link com.google.gson.GsonBuilder}
 * to configure a {@link com.google.gson.Gson} instance to properly translate Java field
 * names into the desired JSON field names.
 *
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
public enum FieldNamingPolicy implements FieldNamingStrategy {

  /**
   * Using this naming policy with Gson will ensure that the field name is
   * unchanged.
   */
  IDENTITY() {
    @Override public String translateName(Field f) {
      return f.getName();
    }
  },

  /**
   * Using this naming policy with Gson will ensure that the first "letter" of the Java
   * field name is capitalized when serialized to its JSON form.
   *
   * 

Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":

*
    *
  • someFieldName ---> SomeFieldName
  • *
  • _someFieldName ---> _SomeFieldName
  • *
*/ UPPER_CAMEL_CASE() { @Override public String translateName(Field f) { return upperCaseFirstLetter(f.getName()); } }, /** * Using this naming policy with Gson will ensure that the first "letter" of the Java * field name is capitalized when serialized to its JSON form and the words will be * separated by a space. * *

Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":

*
    *
  • someFieldName ---> Some Field Name
  • *
  • _someFieldName ---> _Some Field Name
  • *
* * @since 1.4 */ UPPER_CAMEL_CASE_WITH_SPACES() { @Override public String translateName(Field f) { return upperCaseFirstLetter(separateCamelCase(f.getName(), " ")); } }, /** * Using this naming policy with Gson will modify the Java Field name from its camel cased * form to a lower case field name where each word is separated by an underscore (_). * *

Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":

*
    *
  • someFieldName ---> some_field_name
  • *
  • _someFieldName ---> _some_field_name
  • *
  • aStringField ---> a_string_field
  • *
  • aURL ---> a_u_r_l
  • *
*/ LOWER_CASE_WITH_UNDERSCORES() { @Override public String translateName(Field f) { return separateCamelCase(f.getName(), "_").toLowerCase(Locale.ENGLISH); } }, /** * Using this naming policy with Gson will modify the Java Field name from its camel cased * form to a lower case field name where each word is separated by a dash (-). * *

Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":

*
    *
  • someFieldName ---> some-field-name
  • *
  • _someFieldName ---> _some-field-name
  • *
  • aStringField ---> a-string-field
  • *
  • aURL ---> a-u-r-l
  • *
* Using dashes in JavaScript is not recommended since dash is also used for a minus sign in * expressions. This requires that a field named with dashes is always accessed as a quoted * property like {@code myobject['my-field']}. Accessing it as an object field * {@code myobject.my-field} will result in an unintended javascript expression. * @since 1.4 */ LOWER_CASE_WITH_DASHES() { @Override public String translateName(Field f) { return separateCamelCase(f.getName(), "-").toLowerCase(Locale.ENGLISH); } }; /** * Converts the field name that uses camel-case define word separation into * separate words that are separated by the provided {@code separatorString}. */ static String separateCamelCase(String name, String separator) { StringBuilder translation = new StringBuilder(); for (int i = 0; i < name.length(); i++) { char character = name.charAt(i); if (Character.isUpperCase(character) && translation.length() != 0) { translation.append(separator); } translation.append(character); } return translation.toString(); } /** * Ensures the JSON field names begins with an upper case letter. */ static String upperCaseFirstLetter(String name) { StringBuilder fieldNameBuilder = new StringBuilder(); int index = 0; char firstCharacter = name.charAt(index); while (index < name.length() - 1) { if (Character.isLetter(firstCharacter)) { break; } fieldNameBuilder.append(firstCharacter); firstCharacter = name.charAt(++index); } if (index == name.length()) { return fieldNameBuilder.toString(); } if (!Character.isUpperCase(firstCharacter)) { String modifiedTarget = modifyString(Character.toUpperCase(firstCharacter), name, ++index); return fieldNameBuilder.append(modifiedTarget).toString(); } else { return name; } } private static String modifyString(char firstCharacter, String srcString, int indexOfSubstring) { return (indexOfSubstring < srcString.length()) ? firstCharacter + srcString.substring(indexOfSubstring) : String.valueOf(firstCharacter); } }