com.google.gson.GsonBuilder Maven / Gradle / Ivy
/*
* 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.Type;
import java.sql.Timestamp;
import java.text.DateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.google.gson.internal.$Gson$Preconditions;
import com.google.gson.internal.Excluder;
import com.google.gson.internal.bind.TreeTypeAdapter;
import com.google.gson.internal.bind.TypeAdapters;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import static com.google.gson.Gson.DEFAULT_COMPLEX_MAP_KEYS;
import static com.google.gson.Gson.DEFAULT_ESCAPE_HTML;
import static com.google.gson.Gson.DEFAULT_JSON_NON_EXECUTABLE;
import static com.google.gson.Gson.DEFAULT_LENIENT;
import static com.google.gson.Gson.DEFAULT_PRETTY_PRINT;
import static com.google.gson.Gson.DEFAULT_SERIALIZE_NULLS;
import static com.google.gson.Gson.DEFAULT_SPECIALIZE_FLOAT_VALUES;
/**
* Use this builder to construct a {@link Gson} instance when you need to set configuration
* options other than the default. For {@link Gson} with default configuration, it is simpler to
* use {@code new Gson()}. {@code GsonBuilder} is best used by creating it, and then invoking its
* various configuration methods, and finally calling create.
*
* The following is an example shows how to use the {@code GsonBuilder} to construct a Gson
* instance:
*
*
* Gson gson = new GsonBuilder()
* .registerTypeAdapter(Id.class, new IdTypeAdapter())
* .enableComplexMapKeySerialization()
* .serializeNulls()
* .setDateFormat(DateFormat.LONG)
* .setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE)
* .setPrettyPrinting()
* .setVersion(1.0)
* .create();
*
*
* NOTES:
*
* - the order of invocation of configuration methods does not matter.
* - The default serialization of {@link Date} and its subclasses in Gson does
* not contain time-zone information. So, if you are using date/time instances,
* use {@code GsonBuilder} and its {@code setDateFormat} methods.
*
*
*
* @author Inderjeet Singh
* @author Joel Leitch
* @author Jesse Wilson
*/
public final class GsonBuilder {
private Excluder excluder = Excluder.DEFAULT;
private LongSerializationPolicy longSerializationPolicy = LongSerializationPolicy.DEFAULT;
private FieldNamingStrategy fieldNamingPolicy = FieldNamingPolicy.IDENTITY;
private final Map> instanceCreators
= new HashMap>();
private final List factories = new ArrayList();
/** tree-style hierarchy factories. These come after factories for backwards compatibility. */
private final List hierarchyFactories = new ArrayList();
private boolean serializeNulls = DEFAULT_SERIALIZE_NULLS;
private String datePattern;
private int dateStyle = DateFormat.DEFAULT;
private int timeStyle = DateFormat.DEFAULT;
private boolean complexMapKeySerialization = DEFAULT_COMPLEX_MAP_KEYS;
private boolean serializeSpecialFloatingPointValues = DEFAULT_SPECIALIZE_FLOAT_VALUES;
private boolean escapeHtmlChars = DEFAULT_ESCAPE_HTML;
private boolean prettyPrinting = DEFAULT_PRETTY_PRINT;
private boolean generateNonExecutableJson = DEFAULT_JSON_NON_EXECUTABLE;
private boolean lenient = DEFAULT_LENIENT;
/**
* Creates a GsonBuilder instance that can be used to build Gson with various configuration
* settings. GsonBuilder follows the builder pattern, and it is typically used by first
* invoking various configuration methods to set desired options, and finally calling
* {@link #create()}.
*/
public GsonBuilder() {
}
/**
* Constructs a GsonBuilder instance from a Gson instance. The newly constructed GsonBuilder
* has the same configuration as the previously built Gson instance.
*
* @param gson the gson instance whose configuration should by applied to a new GsonBuilder.
*/
GsonBuilder(Gson gson) {
this.excluder = gson.excluder;
this.fieldNamingPolicy = gson.fieldNamingStrategy;
this.instanceCreators.putAll(gson.instanceCreators);
this.serializeNulls = gson.serializeNulls;
this.complexMapKeySerialization = gson.complexMapKeySerialization;
this.generateNonExecutableJson = gson.generateNonExecutableJson;
this.escapeHtmlChars = gson.htmlSafe;
this.prettyPrinting = gson.prettyPrinting;
this.lenient = gson.lenient;
this.serializeSpecialFloatingPointValues = gson.serializeSpecialFloatingPointValues;
this.longSerializationPolicy = gson.longSerializationPolicy;
this.datePattern = gson.datePattern;
this.dateStyle = gson.dateStyle;
this.timeStyle = gson.timeStyle;
this.factories.addAll(gson.builderFactories);
this.hierarchyFactories.addAll(gson.builderHierarchyFactories);
}
/**
* Configures Gson to enable versioning support.
*
* @param ignoreVersionsAfter any field or type marked with a version higher than this value
* are ignored during serialization or deserialization.
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
*/
public GsonBuilder setVersion(double ignoreVersionsAfter) {
excluder = excluder.withVersion(ignoreVersionsAfter);
return this;
}
/**
* Configures Gson to excludes all class fields that have the specified modifiers. By default,
* Gson will exclude all fields marked transient or static. This method will override that
* behavior.
*
* @param modifiers the field modifiers. You must use the modifiers specified in the
* {@link java.lang.reflect.Modifier} class. For example,
* {@link java.lang.reflect.Modifier#TRANSIENT},
* {@link java.lang.reflect.Modifier#STATIC}.
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
*/
public GsonBuilder excludeFieldsWithModifiers(int... modifiers) {
excluder = excluder.withModifiers(modifiers);
return this;
}
/**
* Makes the output JSON non-executable in Javascript by prefixing the generated JSON with some
* special text. This prevents attacks from third-party sites through script sourcing. See
* Gson Issue 42
* for details.
*
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.3
*/
public GsonBuilder generateNonExecutableJson() {
this.generateNonExecutableJson = true;
return this;
}
/**
* Configures Gson to exclude all fields from consideration for serialization or deserialization
* that do not have the {@link com.google.gson.annotations.Expose} annotation.
*
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
*/
public GsonBuilder excludeFieldsWithoutExposeAnnotation() {
excluder = excluder.excludeFieldsWithoutExposeAnnotation();
return this;
}
/**
* Configure Gson to serialize null fields. By default, Gson omits all fields that are null
* during serialization.
*
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.2
*/
public GsonBuilder serializeNulls() {
this.serializeNulls = true;
return this;
}
/**
* Enabling this feature will only change the serialized form if the map key is
* a complex type (i.e. non-primitive) in its serialized JSON
* form. The default implementation of map serialization uses {@code toString()}
* on the key; however, when this is called then one of the following cases
* apply:
*
* Maps as JSON objects
* For this case, assume that a type adapter is registered to serialize and
* deserialize some {@code Point} class, which contains an x and y coordinate,
* to/from the JSON Primitive string value {@code "(x,y)"}. The Java map would
* then be serialized as a {@link JsonObject}.
*
* Below is an example:
*
{@code
* Gson gson = new GsonBuilder()
* .register(Point.class, new MyPointTypeAdapter())
* .enableComplexMapKeySerialization()
* .create();
*
* Map original = new LinkedHashMap();
* original.put(new Point(5, 6), "a");
* original.put(new Point(8, 8), "b");
* System.out.println(gson.toJson(original, type));
* }
* The above code prints this JSON object: {@code
* {
* "(5,6)": "a",
* "(8,8)": "b"
* }
* }
*
* Maps as JSON arrays
* For this case, assume that a type adapter was NOT registered for some
* {@code Point} class, but rather the default Gson serialization is applied.
* In this case, some {@code new Point(2,3)} would serialize as {@code
* {"x":2,"y":5}}.
*
* Given the assumption above, a {@code Map} will be
* serialize as an array of arrays (can be viewed as an entry set of pairs).
*
* Below is an example of serializing complex types as JSON arrays:
*
{@code
* Gson gson = new GsonBuilder()
* .enableComplexMapKeySerialization()
* .create();
*
* Map original = new LinkedHashMap();
* original.put(new Point(5, 6), "a");
* original.put(new Point(8, 8), "b");
* System.out.println(gson.toJson(original, type));
* }
*
* The JSON output would look as follows:
* {@code
* [
* [
* {
* "x": 5,
* "y": 6
* },
* "a"
* ],
* [
* {
* "x": 8,
* "y": 8
* },
* "b"
* ]
* ]
* }
*
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.7
*/
public GsonBuilder enableComplexMapKeySerialization() {
complexMapKeySerialization = true;
return this;
}
/**
* Configures Gson to exclude inner classes during serialization.
*
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.3
*/
public GsonBuilder disableInnerClassSerialization() {
excluder = excluder.disableInnerClassSerialization();
return this;
}
/**
* Configures Gson to apply a specific serialization policy for {@code Long} and {@code long}
* objects.
*
* @param serializationPolicy the particular policy to use for serializing longs.
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.3
*/
public GsonBuilder setLongSerializationPolicy(LongSerializationPolicy serializationPolicy) {
this.longSerializationPolicy = serializationPolicy;
return this;
}
/**
* Configures Gson to apply a specific naming policy to an object's field during serialization
* and deserialization.
*
* @param namingConvention the JSON field naming convention to use for serialization and
* deserialization.
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
*/
public GsonBuilder setFieldNamingPolicy(FieldNamingPolicy namingConvention) {
this.fieldNamingPolicy = namingConvention;
return this;
}
/**
* Configures Gson to apply a specific naming policy strategy to an object's field during
* serialization and deserialization.
*
* @param fieldNamingStrategy the actual naming strategy to apply to the fields
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.3
*/
public GsonBuilder setFieldNamingStrategy(FieldNamingStrategy fieldNamingStrategy) {
this.fieldNamingPolicy = fieldNamingStrategy;
return this;
}
/**
* Configures Gson to apply a set of exclusion strategies during both serialization and
* deserialization. Each of the {@code strategies} will be applied as a disjunction rule.
* This means that if one of the {@code strategies} suggests that a field (or class) should be
* skipped then that field (or object) is skipped during serialization/deserialization.
*
* @param strategies the set of strategy object to apply during object (de)serialization.
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.4
*/
public GsonBuilder setExclusionStrategies(ExclusionStrategy... strategies) {
for (ExclusionStrategy strategy : strategies) {
excluder = excluder.withExclusionStrategy(strategy, true, true);
}
return this;
}
/**
* Configures Gson to apply the passed in exclusion strategy during serialization.
* If this method is invoked numerous times with different exclusion strategy objects
* then the exclusion strategies that were added will be applied as a disjunction rule.
* This means that if one of the added exclusion strategies suggests that a field (or
* class) should be skipped then that field (or object) is skipped during its
* serialization.
*
* @param strategy an exclusion strategy to apply during serialization.
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.7
*/
public GsonBuilder addSerializationExclusionStrategy(ExclusionStrategy strategy) {
excluder = excluder.withExclusionStrategy(strategy, true, false);
return this;
}
/**
* Configures Gson to apply the passed in exclusion strategy during deserialization.
* If this method is invoked numerous times with different exclusion strategy objects
* then the exclusion strategies that were added will be applied as a disjunction rule.
* This means that if one of the added exclusion strategies suggests that a field (or
* class) should be skipped then that field (or object) is skipped during its
* deserialization.
*
* @param strategy an exclusion strategy to apply during deserialization.
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.7
*/
public GsonBuilder addDeserializationExclusionStrategy(ExclusionStrategy strategy) {
excluder = excluder.withExclusionStrategy(strategy, false, true);
return this;
}
/**
* Configures Gson to output Json that fits in a page for pretty printing. This option only
* affects Json serialization.
*
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
*/
public GsonBuilder setPrettyPrinting() {
prettyPrinting = true;
return this;
}
/**
* By default, Gson is strict and only accepts JSON as specified by
* RFC 4627. This option makes the parser
* liberal in what it accepts.
*
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @see JsonReader#setLenient(boolean)
*/
public GsonBuilder setLenient() {
lenient = true;
return this;
}
/**
* By default, Gson escapes HTML characters such as < > etc. Use this option to configure
* Gson to pass-through HTML characters as is.
*
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.3
*/
public GsonBuilder disableHtmlEscaping() {
this.escapeHtmlChars = false;
return this;
}
/**
* Configures Gson to serialize {@code Date} objects according to the pattern provided. You can
* call this method or {@link #setDateFormat(int)} multiple times, but only the last invocation
* will be used to decide the serialization format.
*
* The date format will be used to serialize and deserialize {@link java.util.Date}, {@link
* java.sql.Timestamp} and {@link java.sql.Date}.
*
*
Note that this pattern must abide by the convention provided by {@code SimpleDateFormat}
* class. See the documentation in {@link java.text.SimpleDateFormat} for more information on
* valid date and time patterns.
*
* @param pattern the pattern that dates will be serialized/deserialized to/from
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.2
*/
public GsonBuilder setDateFormat(String pattern) {
// TODO(Joel): Make this fail fast if it is an invalid date format
this.datePattern = pattern;
return this;
}
/**
* Configures Gson to to serialize {@code Date} objects according to the style value provided.
* You can call this method or {@link #setDateFormat(String)} multiple times, but only the last
* invocation will be used to decide the serialization format.
*
* Note that this style value should be one of the predefined constants in the
* {@code DateFormat} class. See the documentation in {@link java.text.DateFormat} for more
* information on the valid style constants.
*
* @param style the predefined date style that date objects will be serialized/deserialized
* to/from
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.2
*/
public GsonBuilder setDateFormat(int style) {
this.dateStyle = style;
this.datePattern = null;
return this;
}
/**
* Configures Gson to to serialize {@code Date} objects according to the style value provided.
* You can call this method or {@link #setDateFormat(String)} multiple times, but only the last
* invocation will be used to decide the serialization format.
*
* Note that this style value should be one of the predefined constants in the
* {@code DateFormat} class. See the documentation in {@link java.text.DateFormat} for more
* information on the valid style constants.
*
* @param dateStyle the predefined date style that date objects will be serialized/deserialized
* to/from
* @param timeStyle the predefined style for the time portion of the date objects
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.2
*/
public GsonBuilder setDateFormat(int dateStyle, int timeStyle) {
this.dateStyle = dateStyle;
this.timeStyle = timeStyle;
this.datePattern = null;
return this;
}
/**
* Configures Gson for custom serialization or deserialization. This method combines the
* registration of an {@link TypeAdapter}, {@link InstanceCreator}, {@link JsonSerializer}, and a
* {@link JsonDeserializer}. It is best used when a single object {@code typeAdapter} implements
* all the required interfaces for custom serialization with Gson. If a type adapter was
* previously registered for the specified {@code type}, it is overwritten.
*
* This registers the type specified and no other types: you must manually register related
* types! For example, applications registering {@code boolean.class} should also register {@code
* Boolean.class}.
*
* @param type the type definition for the type adapter being registered
* @param typeAdapter This object must implement at least one of the {@link TypeAdapter},
* {@link InstanceCreator}, {@link JsonSerializer}, and a {@link JsonDeserializer} interfaces.
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
*/
@SuppressWarnings({"unchecked", "rawtypes"})
public GsonBuilder registerTypeAdapter(Type type, Object typeAdapter) {
$Gson$Preconditions.checkArgument(typeAdapter instanceof JsonSerializer
|| typeAdapter instanceof JsonDeserializer
|| typeAdapter instanceof InstanceCreator
|| typeAdapter instanceof TypeAdapter);
if (typeAdapter instanceof InstanceCreator) {
instanceCreators.put(type, (InstanceCreator) typeAdapter);
}
if (typeAdapter instanceof JsonSerializer || typeAdapter instanceof JsonDeserializer) {
TypeToken typeToken = TypeToken.get(type);
factories.add(TreeTypeAdapter.newFactoryWithMatchRawType(typeToken, typeAdapter));
}
if (typeAdapter instanceof TypeAdapter) {
factories.add(TypeAdapters.newFactory(TypeToken.get(type), (TypeAdapter)typeAdapter));
}
return this;
}
/**
* Register a factory for type adapters. Registering a factory is useful when the type
* adapter needs to be configured based on the type of the field being processed. Gson
* is designed to handle a large number of factories, so you should consider registering
* them to be at par with registering an individual type adapter.
*
* @since 2.1
*/
public GsonBuilder registerTypeAdapterFactory(TypeAdapterFactory factory) {
factories.add(factory);
return this;
}
/**
* Configures Gson for custom serialization or deserialization for an inheritance type hierarchy.
* This method combines the registration of a {@link TypeAdapter}, {@link JsonSerializer} and
* a {@link JsonDeserializer}. If a type adapter was previously registered for the specified
* type hierarchy, it is overridden. If a type adapter is registered for a specific type in
* the type hierarchy, it will be invoked instead of the one registered for the type hierarchy.
*
* @param baseType the class definition for the type adapter being registered for the base class
* or interface
* @param typeAdapter This object must implement at least one of {@link TypeAdapter},
* {@link JsonSerializer} or {@link JsonDeserializer} interfaces.
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.7
*/
@SuppressWarnings({"unchecked", "rawtypes"})
public GsonBuilder registerTypeHierarchyAdapter(Class baseType, Object typeAdapter) {
$Gson$Preconditions.checkArgument(typeAdapter instanceof JsonSerializer
|| typeAdapter instanceof JsonDeserializer
|| typeAdapter instanceof TypeAdapter);
if (typeAdapter instanceof JsonDeserializer || typeAdapter instanceof JsonSerializer) {
hierarchyFactories.add(TreeTypeAdapter.newTypeHierarchyFactory(baseType, typeAdapter));
}
if (typeAdapter instanceof TypeAdapter) {
factories.add(TypeAdapters.newTypeHierarchyFactory(baseType, (TypeAdapter)typeAdapter));
}
return this;
}
/**
* Section 2.4 of JSON specification disallows
* special double values (NaN, Infinity, -Infinity). However,
* Javascript
* specification (see section 4.3.20, 4.3.22, 4.3.23) allows these values as valid Javascript
* values. Moreover, most JavaScript engines will accept these special values in JSON without
* problem. So, at a practical level, it makes sense to accept these values as valid JSON even
* though JSON specification disallows them.
*
*
Gson always accepts these special values during deserialization. However, it outputs
* strictly compliant JSON. Hence, if it encounters a float value {@link Float#NaN},
* {@link Float#POSITIVE_INFINITY}, {@link Float#NEGATIVE_INFINITY}, or a double value
* {@link Double#NaN}, {@link Double#POSITIVE_INFINITY}, {@link Double#NEGATIVE_INFINITY}, it
* will throw an {@link IllegalArgumentException}. This method provides a way to override the
* default behavior when you know that the JSON receiver will be able to handle these special
* values.
*
* @return a reference to this {@code GsonBuilder} object to fulfill the "Builder" pattern
* @since 1.3
*/
public GsonBuilder serializeSpecialFloatingPointValues() {
this.serializeSpecialFloatingPointValues = true;
return this;
}
/**
* Creates a {@link Gson} instance based on the current configuration. This method is free of
* side-effects to this {@code GsonBuilder} instance and hence can be called multiple times.
*
* @return an instance of Gson configured with the options currently set in this builder
*/
public Gson create() {
List factories = new ArrayList(this.factories.size() + this.hierarchyFactories.size() + 3);
factories.addAll(this.factories);
Collections.reverse(factories);
List hierarchyFactories = new ArrayList(this.hierarchyFactories);
Collections.reverse(hierarchyFactories);
factories.addAll(hierarchyFactories);
addTypeAdaptersForDate(datePattern, dateStyle, timeStyle, factories);
return new Gson(excluder, fieldNamingPolicy, instanceCreators,
serializeNulls, complexMapKeySerialization,
generateNonExecutableJson, escapeHtmlChars, prettyPrinting, lenient,
serializeSpecialFloatingPointValues, longSerializationPolicy,
datePattern, dateStyle, timeStyle,
this.factories, this.hierarchyFactories, factories);
}
@SuppressWarnings("unchecked")
private void addTypeAdaptersForDate(String datePattern, int dateStyle, int timeStyle,
List factories) {
DefaultDateTypeAdapter dateTypeAdapter;
TypeAdapter timestampTypeAdapter;
TypeAdapter javaSqlDateTypeAdapter;
if (datePattern != null && !"".equals(datePattern.trim())) {
dateTypeAdapter = new DefaultDateTypeAdapter(Date.class, datePattern);
timestampTypeAdapter = (TypeAdapter) new DefaultDateTypeAdapter(Timestamp.class, datePattern);
javaSqlDateTypeAdapter = (TypeAdapter) new DefaultDateTypeAdapter(java.sql.Date.class, datePattern);
} else if (dateStyle != DateFormat.DEFAULT && timeStyle != DateFormat.DEFAULT) {
dateTypeAdapter = new DefaultDateTypeAdapter(Date.class, dateStyle, timeStyle);
timestampTypeAdapter = (TypeAdapter) new DefaultDateTypeAdapter(Timestamp.class, dateStyle, timeStyle);
javaSqlDateTypeAdapter = (TypeAdapter) new DefaultDateTypeAdapter(java.sql.Date.class, dateStyle, timeStyle);
} else {
return;
}
factories.add(TypeAdapters.newFactory(Date.class, dateTypeAdapter));
factories.add(TypeAdapters.newFactory(Timestamp.class, timestampTypeAdapter));
factories.add(TypeAdapters.newFactory(java.sql.Date.class, javaSqlDateTypeAdapter));
}
}