| 1 | /* |
| 2 | * Copyright (C) 2008 Google Inc. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package com.google.gson; |
| 18 | |
| 19 | import java.lang.reflect.Field; |
| 20 | import java.util.Locale; |
| 21 | |
| 22 | /** |
| 23 | * An enumeration that defines a few standard naming conventions for JSON field names. |
| 24 | * This enumeration should be used in conjunction with {@link com.google.gson.GsonBuilder} |
| 25 | * to configure a {@link com.google.gson.Gson} instance to properly translate Java field |
| 26 | * names into the desired JSON field names. |
| 27 | * |
| 28 | * @author Inderjeet Singh |
| 29 | * @author Joel Leitch |
| 30 | */ |
| 31 | public enum FieldNamingPolicy implements FieldNamingStrategy { |
| 32 | |
| 33 | /** |
| 34 | * Using this naming policy with Gson will ensure that the field name is |
| 35 | * unchanged. |
| 36 | */ |
| 37 | IDENTITY() { |
| 38 | public String translateName(Field f) { |
| 39 | return f.getName(); |
| 40 | } |
| 41 | }, |
| 42 | |
| 43 | /** |
| 44 | * Using this naming policy with Gson will ensure that the first "letter" of the Java |
| 45 | * field name is capitalized when serialized to its JSON form. |
| 46 | * |
| 47 | * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p> |
| 48 | * <ul> |
| 49 | * <li>someFieldName ---> SomeFieldName</li> |
| 50 | * <li>_someFieldName ---> _SomeFieldName</li> |
| 51 | * </ul> |
| 52 | */ |
| 53 | UPPER_CAMEL_CASE() { |
| 54 | public String translateName(Field f) { |
| 55 | return upperCaseFirstLetter(f.getName()); |
| 56 | } |
| 57 | }, |
| 58 | |
| 59 | /** |
| 60 | * Using this naming policy with Gson will ensure that the first "letter" of the Java |
| 61 | * field name is capitalized when serialized to its JSON form and the words will be |
| 62 | * separated by a space. |
| 63 | * |
| 64 | * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p> |
| 65 | * <ul> |
| 66 | * <li>someFieldName ---> Some Field Name</li> |
| 67 | * <li>_someFieldName ---> _Some Field Name</li> |
| 68 | * </ul> |
| 69 | * |
| 70 | * @since 1.4 |
| 71 | */ |
| 72 | UPPER_CAMEL_CASE_WITH_SPACES() { |
| 73 | public String translateName(Field f) { |
| 74 | return upperCaseFirstLetter(separateCamelCase(f.getName(), " ")); |
| 75 | } |
| 76 | }, |
| 77 | |
| 78 | /** |
| 79 | * Using this naming policy with Gson will modify the Java Field name from its camel cased |
| 80 | * form to a lower case field name where each word is separated by an underscore (_). |
| 81 | * |
| 82 | * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p> |
| 83 | * <ul> |
| 84 | * <li>someFieldName ---> some_field_name</li> |
| 85 | * <li>_someFieldName ---> _some_field_name</li> |
| 86 | * <li>aStringField ---> a_string_field</li> |
| 87 | * <li>aURL ---> a_u_r_l</li> |
| 88 | * </ul> |
| 89 | */ |
| 90 | LOWER_CASE_WITH_UNDERSCORES() { |
| 91 | public String translateName(Field f) { |
| 92 | return separateCamelCase(f.getName(), "_").toLowerCase(Locale.ENGLISH); |
| 93 | } |
| 94 | }, |
| 95 | |
| 96 | /** |
| 97 | * Using this naming policy with Gson will modify the Java Field name from its camel cased |
| 98 | * form to a lower case field name where each word is separated by a dash (-). |
| 99 | * |
| 100 | * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p> |
| 101 | * <ul> |
| 102 | * <li>someFieldName ---> some-field-name</li> |
| 103 | * <li>_someFieldName ---> _some-field-name</li> |
| 104 | * <li>aStringField ---> a-string-field</li> |
| 105 | * <li>aURL ---> a-u-r-l</li> |
| 106 | * </ul> |
| 107 | * Using dashes in JavaScript is not recommended since dash is also used for a minus sign in |
| 108 | * expressions. This requires that a field named with dashes is always accessed as a quoted |
| 109 | * property like {@code myobject['my-field']}. Accessing it as an object field |
| 110 | * {@code myobject.my-field} will result in an unintended javascript expression. |
| 111 | * @since 1.4 |
| 112 | */ |
| 113 | LOWER_CASE_WITH_DASHES() { |
| 114 | public String translateName(Field f) { |
| 115 | return separateCamelCase(f.getName(), "-").toLowerCase(Locale.ENGLISH); |
| 116 | } |
| 117 | }; |
| 118 | |
| 119 | /** |
| 120 | * Converts the field name that uses camel-case define word separation into |
| 121 | * separate words that are separated by the provided {@code separatorString}. |
| 122 | */ |
| 123 | private static String separateCamelCase(String name, String separator) { |
| 124 | StringBuilder translation = new StringBuilder(); |
| 125 | for (int i = 0; i < name.length(); i++) { |
| 126 | char character = name.charAt(i); |
| 127 | if (Character.isUpperCase(character) && translation.length() != 0) { |
| 128 | translation.append(separator); |
| 129 | } |
| 130 | translation.append(character); |
| 131 | } |
| 132 | return translation.toString(); |
| 133 | } |
| 134 | |
| 135 | /** |
| 136 | * Ensures the JSON field names begins with an upper case letter. |
| 137 | */ |
| 138 | private static String upperCaseFirstLetter(String name) { |
| 139 | StringBuilder fieldNameBuilder = new StringBuilder(); |
| 140 | int index = 0; |
| 141 | char firstCharacter = name.charAt(index); |
| 142 | |
| 143 | while (index < name.length() - 1) { |
| 144 | if (Character.isLetter(firstCharacter)) { |
| 145 | break; |
| 146 | } |
| 147 | |
| 148 | fieldNameBuilder.append(firstCharacter); |
| 149 | firstCharacter = name.charAt(++index); |
| 150 | } |
| 151 | |
| 152 | if (index == name.length()) { |
| 153 | return fieldNameBuilder.toString(); |
| 154 | } |
| 155 | |
| 156 | if (!Character.isUpperCase(firstCharacter)) { |
| 157 | String modifiedTarget = modifyString(Character.toUpperCase(firstCharacter), name, ++index); |
| 158 | return fieldNameBuilder.append(modifiedTarget).toString(); |
| 159 | } else { |
| 160 | return name; |
| 161 | } |
| 162 | } |
| 163 | |
| 164 | private static String modifyString(char firstCharacter, String srcString, int indexOfSubstring) { |
| 165 | return (indexOfSubstring < srcString.length()) |
| 166 | ? firstCharacter + srcString.substring(indexOfSubstring) |
| 167 | : String.valueOf(firstCharacter); |
| 168 | } |
| 169 | } |