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Add Gson.fromJson(..., TypeToken) overloads #1700

Merged
merged 12 commits into from
Sep 19, 2022
Merged
4 changes: 2 additions & 2 deletions UserGuide.md
Original file line number Diff line number Diff line change
Expand Up @@ -225,7 +225,7 @@ Collection<Integer> ints = Arrays.asList(1,2,3,4,5);
String json = gson.toJson(ints); // ==> json is [1,2,3,4,5]

// Deserialization
Type collectionType = new TypeToken<Collection<Integer>>(){}.getType();
TypeToken<Collection<Integer>> collectionType = new TypeToken<Collection<Integer>>(){};
Collection<Integer> ints2 = gson.fromJson(json, collectionType);
// ==> ints2 is same as ints
```
Expand Down Expand Up @@ -263,7 +263,7 @@ For deserialization Gson uses the `read` method of the `TypeAdapter` registered

```java
Gson gson = new Gson();
Type mapType = new TypeToken<Map<String, String>>(){}.getType();
TypeToken<Map<String, String>> mapType = new TypeToken<Map<String, String>>(){};
String json = "{\"key\": \"value\"}";

// Deserialization
Expand Down
390 changes: 296 additions & 94 deletions gson/src/main/java/com/google/gson/Gson.java

Large diffs are not rendered by default.

20 changes: 17 additions & 3 deletions gson/src/main/java/com/google/gson/reflect/TypeToken.java
Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@
* runtime.
*
* <p>For example, to create a type literal for {@code List<String>}, you can
* create an empty anonymous inner class:
* create an empty anonymous class:
*
* <p>
* {@code TypeToken<List<String>> list = new TypeToken<List<String>>() {};}
Expand All @@ -43,6 +43,11 @@
* might expect, which gives a false sense of type-safety at compilation time
* and can lead to an unexpected {@code ClassCastException} at runtime.
*
* <p>If the type arguments of the parameterized type are only available at
* runtime, for example when you want to create a {@code List<E>} based on
* a {@code Class<E>} representing the element type, the method
* {@link #getParameterized(Type, Type...)} can be used.
*
* @author Bob Lee
* @author Sven Mawson
* @author Jesse Wilson
Expand Down Expand Up @@ -317,8 +322,17 @@ public static <T> TypeToken<T> get(Class<T> type) {
}

/**
* Gets type literal for the parameterized type represented by applying {@code typeArguments} to
* {@code rawType}.
* Gets a type literal for the parameterized type represented by applying {@code typeArguments} to
* {@code rawType}. This is mainly intended for situations where the type arguments are not
* available at compile time. The following example shows how a type token for {@code Map<K, V>}
* can be created:
* <pre>{@code
* Class<K> keyClass = ...;
* Class<V> valueClass = ...;
* TypeToken<?> mapTypeToken = TypeToken.getParameterized(Map.class, keyClass, valueClass);
* }</pre>
* As seen here the result is a {@code TypeToken<?>}; this method cannot provide any type safety,
* and care must be taken to pass in the correct number of type arguments.
*
* @throws IllegalArgumentException
* If {@code rawType} is not of type {@code Class}, or if the type arguments are invalid for
Expand Down
2 changes: 1 addition & 1 deletion gson/src/test/java/com/google/gson/MixedStreamTest.java
Original file line number Diff line number Diff line change
Expand Up @@ -174,7 +174,7 @@ public void testReadNulls() {
} catch (NullPointerException expected) {
}
try {
gson.fromJson(new JsonReader(new StringReader("true")), null);
gson.fromJson(new JsonReader(new StringReader("true")), (Type) null);
fail();
} catch (NullPointerException expected) {
}
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -16,13 +16,19 @@

package com.google.gson.functional;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import com.google.gson.ParameterizedTypeFixtures.MyParameterizedType;
import com.google.gson.ParameterizedTypeFixtures.MyParameterizedTypeAdapter;
import com.google.gson.ParameterizedTypeFixtures.MyParameterizedTypeInstanceCreator;
import com.google.gson.common.TestTypes.BagOfPrimitives;
import com.google.gson.reflect.TypeToken;
import com.google.gson.stream.JsonReader;
import java.io.Reader;
import java.io.Serializable;
import java.io.StringReader;
Expand All @@ -32,30 +38,32 @@
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import junit.framework.TestCase;
import org.junit.Before;
import org.junit.Test;

/**
* Functional tests for the serialization and deserialization of parameterized types in Gson.
*
* @author Inderjeet Singh
* @author Joel Leitch
*/
public class ParameterizedTypesTest extends TestCase {
public class ParameterizedTypesTest {
private Gson gson;

@Override
protected void setUp() throws Exception {
super.setUp();
@Before
public void setUp() {
gson = new Gson();
}

@Test
public void testParameterizedTypesSerialization() throws Exception {
MyParameterizedType<Integer> src = new MyParameterizedType<>(10);
Type typeOfSrc = new TypeToken<MyParameterizedType<Integer>>() {}.getType();
String json = gson.toJson(src, typeOfSrc);
assertEquals(src.getExpectedJson(), json);
}

@Test
public void testParameterizedTypeDeserialization() throws Exception {
BagOfPrimitives bag = new BagOfPrimitives();
MyParameterizedType<BagOfPrimitives> expected = new MyParameterizedType<>(bag);
Expand All @@ -70,6 +78,7 @@ public void testParameterizedTypeDeserialization() throws Exception {
assertEquals(expected, actual);
}

@Test
public void testTypesWithMultipleParametersSerialization() throws Exception {
MultiParameters<Integer, Float, Double, String, BagOfPrimitives> src =
new MultiParameters<>(10, 1.0F, 2.1D, "abc", new BagOfPrimitives());
Expand All @@ -81,6 +90,7 @@ public void testTypesWithMultipleParametersSerialization() throws Exception {
assertEquals(expected, json);
}

@Test
public void testTypesWithMultipleParametersDeserialization() throws Exception {
Type typeOfTarget = new TypeToken<MultiParameters<Integer, Float, Double, String,
BagOfPrimitives>>() {}.getType();
Expand All @@ -93,6 +103,7 @@ public void testTypesWithMultipleParametersDeserialization() throws Exception {
assertEquals(expected, target);
}

@Test
public void testParameterizedTypeWithCustomSerializer() {
Type ptIntegerType = new TypeToken<MyParameterizedType<Integer>>() {}.getType();
Type ptStringType = new TypeToken<MyParameterizedType<String>>() {}.getType();
Expand All @@ -109,6 +120,7 @@ public void testParameterizedTypeWithCustomSerializer() {
assertEquals(MyParameterizedTypeAdapter.<String>getExpectedJson(stringTarget), json);
}

@Test
public void testParameterizedTypesWithCustomDeserializer() {
Type ptIntegerType = new TypeToken<MyParameterizedType<Integer>>() {}.getType();
Type ptStringType = new TypeToken<MyParameterizedType<String>>() {}.getType();
Expand All @@ -130,6 +142,7 @@ public void testParameterizedTypesWithCustomDeserializer() {
assertEquals("abc", stringTarget.value);
}

@Test
public void testParameterizedTypesWithWriterSerialization() throws Exception {
Writer writer = new StringWriter();
MyParameterizedType<Integer> src = new MyParameterizedType<>(10);
Expand All @@ -138,6 +151,7 @@ public void testParameterizedTypesWithWriterSerialization() throws Exception {
assertEquals(src.getExpectedJson(), writer.toString());
}

@Test
public void testParameterizedTypeWithReaderDeserialization() throws Exception {
BagOfPrimitives bag = new BagOfPrimitives();
MyParameterizedType<BagOfPrimitives> expected = new MyParameterizedType<>(bag);
Expand All @@ -158,6 +172,7 @@ private static <T> T[] arrayOf(T... args) {
return args;
}

@Test
public void testVariableTypeFieldsAndGenericArraysSerialization() throws Exception {
Integer obj = 0;
Integer[] array = { 1, 2, 3 };
Expand All @@ -174,6 +189,7 @@ public void testVariableTypeFieldsAndGenericArraysSerialization() throws Excepti
assertEquals(objToSerialize.getExpectedJson(), json);
}

@Test
public void testVariableTypeFieldsAndGenericArraysDeserialization() throws Exception {
Integer obj = 0;
Integer[] array = { 1, 2, 3 };
Expand All @@ -191,6 +207,7 @@ public void testVariableTypeFieldsAndGenericArraysDeserialization() throws Excep
assertEquals(objAfterDeserialization.getExpectedJson(), json);
}

@Test
public void testVariableTypeDeserialization() throws Exception {
Type typeOfSrc = new TypeToken<ObjectWithTypeVariables<Integer>>() {}.getType();
ObjectWithTypeVariables<Integer> objToSerialize =
Expand All @@ -201,6 +218,7 @@ public void testVariableTypeDeserialization() throws Exception {
assertEquals(objAfterDeserialization.getExpectedJson(), json);
}

@Test
public void testVariableTypeArrayDeserialization() throws Exception {
Integer[] array = { 1, 2, 3 };

Expand All @@ -213,6 +231,7 @@ public void testVariableTypeArrayDeserialization() throws Exception {
assertEquals(objAfterDeserialization.getExpectedJson(), json);
}

@Test
public void testParameterizedTypeWithVariableTypeDeserialization() throws Exception {
List<Integer> list = new ArrayList<>();
list.add(4);
Expand All @@ -227,6 +246,7 @@ public void testParameterizedTypeWithVariableTypeDeserialization() throws Except
assertEquals(objAfterDeserialization.getExpectedJson(), json);
}

@Test
public void testParameterizedTypeGenericArraysSerialization() throws Exception {
List<Integer> list = new ArrayList<>();
list.add(1);
Expand All @@ -240,6 +260,7 @@ public void testParameterizedTypeGenericArraysSerialization() throws Exception {
assertEquals("{\"arrayOfListOfTypeParameters\":[[1,2],[1,2]]}", json);
}

@Test
public void testParameterizedTypeGenericArraysDeserialization() throws Exception {
List<Integer> list = new ArrayList<>();
list.add(1);
Expand Down Expand Up @@ -483,18 +504,63 @@ public static final class Amount<Q extends Quantity>
int value = 30;
}

@Test
public void testDeepParameterizedTypeSerialization() {
Amount<MyQuantity> amount = new Amount<>();
String json = gson.toJson(amount);
assertTrue(json.contains("value"));
assertTrue(json.contains("30"));
}

@Test
public void testDeepParameterizedTypeDeserialization() {
String json = "{value:30}";
Type type = new TypeToken<Amount<MyQuantity>>() {}.getType();
Amount<MyQuantity> amount = gson.fromJson(json, type);
assertEquals(30, amount.value);
}
// End: tests to reproduce issue 103

private static void assertCorrectlyDeserialized(Object object) {
@SuppressWarnings("unchecked")
List<Quantity> list = (List<Quantity>) object;
assertEquals(1, list.size());
assertEquals(4, list.get(0).q);
}

@Test
public void testGsonFromJsonTypeToken() {
TypeToken<List<Quantity>> typeToken = new TypeToken<List<Quantity>>() {};
Type type = typeToken.getType();

{
JsonObject jsonObject = new JsonObject();
jsonObject.addProperty("q", 4);
JsonArray jsonArray = new JsonArray();
jsonArray.add(jsonObject);

assertCorrectlyDeserialized(gson.fromJson(jsonArray, typeToken));
assertCorrectlyDeserialized(gson.fromJson(jsonArray, type));
}

String json = "[{\"q\":4}]";

{
assertCorrectlyDeserialized(gson.fromJson(json, typeToken));
assertCorrectlyDeserialized(gson.fromJson(json, type));
}

{
assertCorrectlyDeserialized(gson.fromJson(new StringReader(json), typeToken));
assertCorrectlyDeserialized(gson.fromJson(new StringReader(json), type));
}

{
JsonReader reader = new JsonReader(new StringReader(json));
assertCorrectlyDeserialized(gson.fromJson(reader, typeToken));

reader = new JsonReader(new StringReader(json));
assertCorrectlyDeserialized(gson.fromJson(reader, type));
}
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -33,14 +33,15 @@
*/
public class CollectionsDeserializationBenchmark {

private static final Type LIST_TYPE = new TypeToken<List<BagOfPrimitives>>(){}.getType();
private static final TypeToken<List<BagOfPrimitives>> LIST_TYPE_TOKEN = new TypeToken<List<BagOfPrimitives>>(){};
private static final Type LIST_TYPE = LIST_TYPE_TOKEN.getType();
private Gson gson;
private String json;

public static void main(String[] args) {
NonUploadingCaliperRunner.run(CollectionsDeserializationBenchmark.class, args);
}

@BeforeExperiment
void setUp() throws Exception {
this.gson = new Gson();
Expand All @@ -51,12 +52,12 @@ void setUp() throws Exception {
this.json = gson.toJson(bags, LIST_TYPE);
}

/**
/**
* Benchmark to measure Gson performance for deserializing an object
*/
public void timeCollectionsDefault(int reps) {
for (int i=0; i<reps; ++i) {
gson.fromJson(json, LIST_TYPE);
gson.fromJson(json, LIST_TYPE_TOKEN);
}
}

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -63,11 +63,11 @@ private enum Document {
READER_SHORT(new TypeToken<Feed>() {}, new TypeReference<Feed>() {}),
READER_LONG(new TypeToken<Feed>() {}, new TypeReference<Feed>() {});

private final Type gsonType;
private final TypeToken<?> gsonType;
private final TypeReference<?> jacksonType;

private Document(TypeToken<?> typeToken, TypeReference<?> typeReference) {
this.gsonType = typeToken.getType();
this.gsonType = typeToken;
this.jacksonType = typeReference;
}
}
Expand Down