/*
* 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.
*
* <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() {
@
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.
*
* <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() {
@
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 (_).
*
* <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() {
@
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 (-).
*
* <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() {
@
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 dot (.).
*
* <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 dots in JavaScript is not recommended since dot is also used for a member sign in
* expressions. This requires that a field named with dots 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 2.8
*/
LOWER_CASE_WITH_DOTS() {
@
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,
length =
name.
length();
i <
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);
int
length =
name.
length();
while (
index <
length - 1) {
if (
Character.
isLetter(
firstCharacter)) {
break;
}
fieldNameBuilder.
append(
firstCharacter);
firstCharacter =
name.
charAt(++
index);
}
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);
}
}