/* * 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.annotation.Annotation; import java.lang.reflect.Type; /** * A {@link FieldNamingStrategy} that ensures the JSON field names begins with * an upper case letter. * *
The following is an example:
** class StringWrapper { * public String stringField = "abcd"; * public String _stringField = "efg"; * } * * ModifyFirstLetterNamingPolicy policy = * new ModifyFirstLetterNamingPolicy(LetterModifier.UPPER); * String translatedFieldName = * policy.translateName(StringWrapper.class.getField("stringField")); * * assert("StringField".equals(translatedFieldName)); * * String translatedFieldName = * policy.translateName(StringWrapper.class.getField("_stringField")); * * assert("_StringField".equals(translatedFieldName)); ** * @author Joel Leitch */ class ModifyFirstLetterNamingPolicy extends RecursiveFieldNamingPolicy { public enum LetterModifier { UPPER, LOWER; } private final LetterModifier letterModifier; /** * Creates a new ModifyFirstLetterNamingPolicy that will either modify the first letter of the * target name to either UPPER case or LOWER case depending on the {@code modifier} parameter. * * @param modifier the type of modification that should be performed * @throws IllegalArgumentException if {@code modifier} is null */ public ModifyFirstLetterNamingPolicy(LetterModifier modifier) { Preconditions.checkNotNull(modifier); this.letterModifier = modifier; } @Override protected String translateName(String target, Type fieldType, Annotation[] annotations) { StringBuilder fieldNameBuilder = new StringBuilder(); int index = 0; char firstCharacter = target.charAt(index); while (index < target.length() - 1) { if (Character.isLetter(firstCharacter)) { break; } fieldNameBuilder.append(firstCharacter); firstCharacter = target.charAt(++index); } if (index == target.length()) { return fieldNameBuilder.toString(); } boolean capitalizeFirstLetter = (letterModifier == LetterModifier.UPPER); if (capitalizeFirstLetter && !Character.isUpperCase(firstCharacter)) { String modifiedTarget = modifyString(Character.toUpperCase(firstCharacter), target, ++index); return fieldNameBuilder.append(modifiedTarget).toString(); } else if (!capitalizeFirstLetter && Character.isUpperCase(firstCharacter)) { String modifiedTarget = modifyString(Character.toLowerCase(firstCharacter), target, ++index); return fieldNameBuilder.append(modifiedTarget).toString(); } else { return target; } } private String modifyString(char firstCharacter, String srcString, int indexOfSubstring) { if (indexOfSubstring < srcString.length()) { return firstCharacter + srcString.substring(indexOfSubstring); } else { return String.valueOf(firstCharacter); } } }