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Diffstat (limited to 'gson/src/main/java/com/google/gson/FieldNamingPolicy.java')
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1 files changed, 169 insertions, 0 deletions
diff --git a/gson/src/main/java/com/google/gson/FieldNamingPolicy.java b/gson/src/main/java/com/google/gson/FieldNamingPolicy.java new file mode 100644 index 00000000..6b4c72ca --- /dev/null +++ b/gson/src/main/java/com/google/gson/FieldNamingPolicy.java @@ -0,0 +1,169 @@ +/* + * 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() { + 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. + * + * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p> + * <ul> + * <li>someFieldName ---> SomeFieldName</li> + * <li>_someFieldName ---> _SomeFieldName</li> + * </ul> + */ + UPPER_CAMEL_CASE() { + 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. + * + * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p> + * <ul> + * <li>someFieldName ---> Some Field Name</li> + * <li>_someFieldName ---> _Some Field Name</li> + * </ul> + * + * @since 1.4 + */ + UPPER_CAMEL_CASE_WITH_SPACES() { + 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 (_). + * + * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p> + * <ul> + * <li>someFieldName ---> some_field_name</li> + * <li>_someFieldName ---> _some_field_name</li> + * <li>aStringField ---> a_string_field</li> + * <li>aURL ---> a_u_r_l</li> + * </ul> + */ + LOWER_CASE_WITH_UNDERSCORES() { + 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 (-). + * + * <p>Here's a few examples of the form "Java Field Name" ---> "JSON Field Name":</p> + * <ul> + * <li>someFieldName ---> some-field-name</li> + * <li>_someFieldName ---> _some-field-name</li> + * <li>aStringField ---> a-string-field</li> + * <li>aURL ---> a-u-r-l</li> + * </ul> + * 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() { + 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}. + */ + private 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. + */ + private 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); + } +}
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