-
-
Notifications
You must be signed in to change notification settings - Fork 343
/
ConstructorInstanceFactory.java
135 lines (117 loc) · 5.55 KB
/
ConstructorInstanceFactory.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
/*
* 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 org.jdbi.v3.core.mapper.reflect;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.lang.reflect.Parameter;
import java.lang.reflect.Type;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.jdbi.v3.core.internal.exceptions.Unchecked;
import static java.util.Collections.synchronizedMap;
import static java.util.Objects.requireNonNull;
import static java.util.stream.Collectors.toUnmodifiableList;
class ConstructorInstanceFactory<T> extends InstanceFactory<T> {
private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup();
private static final Map<Constructor, ConstructorHandleAndTypes> CONSTRUCTOR_CACHE = synchronizedMap(new WeakHashMap<>());
private final Constructor<T> constructor;
private final List<Type> types;
private final MethodHandle constructorHandle;
ConstructorInstanceFactory(Constructor<T> constructor) {
super(constructor);
this.constructor = requireNonNull(constructor, "constructor is null");
ConstructorHandleAndTypes constructorHandleAndTypes = getConstructorHandleAndTypes(constructor, super::getTypes);
this.types = constructorHandleAndTypes.getTypes();
this.constructorHandle = constructorHandleAndTypes.getConstructorHandle();
}
@Override
List<Type> getTypes() {
return types;
}
@Override
T newInstance(Object... params) {
return (T) Unchecked.<Object[], Object>function(constructorHandle::invokeWithArguments).apply(params);
}
@Override
public String toString() {
return constructor.toString();
}
// Note: this can be removed once https://bugs.openjdk.org/browse/JDK-8320575 is resolved
private static <T> boolean isGenericInformationLost(Constructor<T> factory) {
// If there is more than one constructor, ensure that the factory constructor is the canonical constructor.
// If so it will need to get the type parameters from the declared fields.
if (factory.getParameters().length != getFields(factory)
.count()) {
return false;
}
boolean lossDetected = false;
for (int i = 0; i < factory.getParameters().length; i++) {
Parameter parameter = factory.getParameters()[i];
Field field = factory.getDeclaringClass().getDeclaredFields()[i];
if (!parameter.getName().equals(field.getName()) || !parameter.getType().equals(field.getType())) {
return false;
}
// Check if the generic type information is lost, due to jdk21 record constructor: https://bugs.openjdk.org/browse/JDK-8320575
if (parameter.getType().getTypeParameters().length > 0
&& !parameter.getParameterizedType().equals(field.getGenericType())) {
lossDetected = true;
}
}
return lossDetected;
}
private static <T> ConstructorHandleAndTypes getConstructorHandleAndTypes(Constructor<T> constructor, Supplier<List<Type>> defaultSupplier) {
return CONSTRUCTOR_CACHE.computeIfAbsent(constructor, ctor -> computeConstructorHandleAndTypes(ctor, defaultSupplier));
}
private static <T> ConstructorHandleAndTypes computeConstructorHandleAndTypes(Constructor<T> constructor, Supplier<List<Type>> defaultSupplier) {
MethodHandle constructorMethodHandle = getConstructorMethodHandle(constructor);
if (isGenericInformationLost(constructor)) {
return new ConstructorHandleAndTypes(constructorMethodHandle, getFields(constructor)
.map(Field::getGenericType)
.collect(toUnmodifiableList()));
}
return new ConstructorHandleAndTypes(constructorMethodHandle, defaultSupplier.get());
}
private static <T> MethodHandle getConstructorMethodHandle(Constructor<T> constructor) {
try {
return LOOKUP.unreflectConstructor(constructor);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
}
}
private static <T> Stream<Field> getFields(Constructor<T> constructor) {
return Arrays.stream(constructor.getDeclaringClass().getDeclaredFields())
.filter(field -> !Modifier.isStatic(field.getModifiers()));
}
private static class ConstructorHandleAndTypes {
private final MethodHandle constructorHandle;
private final List<Type> types;
ConstructorHandleAndTypes(MethodHandle constructorHandle, List<Type> types) {
this.constructorHandle = requireNonNull(constructorHandle, "constructorHandle is null");
this.types = requireNonNull(types, "types is null");
}
public MethodHandle getConstructorHandle() {
return constructorHandle;
}
public List<Type> getTypes() {
return types;
}
}
}