org.springframework.core.SerializableTypeWrapper Maven / Gradle / Ivy
/*
* Copyright 2002-2018 the original author or authors.
*
* 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
*
* https://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.springframework.core;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Proxy;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.lang.reflect.WildcardType;
import org.springframework.lang.Nullable;
import org.springframework.util.ConcurrentReferenceHashMap;
import org.springframework.util.ObjectUtils;
import org.springframework.util.ReflectionUtils;
/**
* Internal utility class that can be used to obtain wrapped {@link Serializable}
* variants of {@link java.lang.reflect.Type java.lang.reflect.Types}.
*
* {@link #forField(Field) Fields} or {@link #forMethodParameter(MethodParameter)
* MethodParameters} can be used as the root source for a serializable type.
* Alternatively, a regular {@link Class} can also be used as source.
*
*
The returned type will either be a {@link Class} or a serializable proxy of
* {@link GenericArrayType}, {@link ParameterizedType}, {@link TypeVariable} or
* {@link WildcardType}. With the exception of {@link Class} (which is final) calls
* to methods that return further {@link Type Types} (for example
* {@link GenericArrayType#getGenericComponentType()}) will be automatically wrapped.
*
* @author Phillip Webb
* @author Juergen Hoeller
* @since 4.0
*/
final class SerializableTypeWrapper {
private static final Class[] SUPPORTED_SERIALIZABLE_TYPES = {
GenericArrayType.class, ParameterizedType.class, TypeVariable.class, WildcardType.class};
static final ConcurrentReferenceHashMap cache = new ConcurrentReferenceHashMap<>(256);
private SerializableTypeWrapper() {
}
/**
* Return a {@link Serializable} variant of {@link Field#getGenericType()}.
*/
@Nullable
public static Type forField(Field field) {
return forTypeProvider(new FieldTypeProvider(field));
}
/**
* Return a {@link Serializable} variant of
* {@link MethodParameter#getGenericParameterType()}.
*/
@Nullable
public static Type forMethodParameter(MethodParameter methodParameter) {
return forTypeProvider(new MethodParameterTypeProvider(methodParameter));
}
/**
* Unwrap the given type, effectively returning the original non-serializable type.
* @param type the type to unwrap
* @return the original non-serializable type
*/
@SuppressWarnings("unchecked")
public static T unwrap(T type) {
Type unwrapped = type;
while (unwrapped instanceof SerializableTypeProxy) {
unwrapped = ((SerializableTypeProxy) type).getTypeProvider().getType();
}
return (unwrapped != null ? (T) unwrapped : type);
}
/**
* Return a {@link Serializable} {@link Type} backed by a {@link TypeProvider} .
* If type artifacts are generally not serializable in the current runtime
* environment, this delegate will simply return the original {@code Type} as-is.
*/
@Nullable
static Type forTypeProvider(TypeProvider provider) {
Type providedType = provider.getType();
if (providedType == null || providedType instanceof Serializable) {
// No serializable type wrapping necessary (e.g. for java.lang.Class)
return providedType;
}
if (GraalDetector.inImageCode() || !Serializable.class.isAssignableFrom(Class.class)) {
// Let's skip any wrapping attempts if types are generally not serializable in
// the current runtime environment (even java.lang.Class itself, e.g. on Graal)
return providedType;
}
// Obtain a serializable type proxy for the given provider...
Type cached = cache.get(providedType);
if (cached != null) {
return cached;
}
for (Class type : SUPPORTED_SERIALIZABLE_TYPES) {
if (type.isInstance(providedType)) {
ClassLoader classLoader = provider.getClass().getClassLoader();
Class[] interfaces = new Class[] {type, SerializableTypeProxy.class, Serializable.class};
InvocationHandler handler = new TypeProxyInvocationHandler(provider);
cached = (Type) Proxy.newProxyInstance(classLoader, interfaces, handler);
cache.put(providedType, cached);
return cached;
}
}
throw new IllegalArgumentException("Unsupported Type class: " + providedType.getClass().getName());
}
/**
* Additional interface implemented by the type proxy.
*/
interface SerializableTypeProxy {
/**
* Return the underlying type provider.
*/
TypeProvider getTypeProvider();
}
/**
* A {@link Serializable} interface providing access to a {@link Type}.
*/
@SuppressWarnings("serial")
interface TypeProvider extends Serializable {
/**
* Return the (possibly non {@link Serializable}) {@link Type}.
*/
@Nullable
Type getType();
/**
* Return the source of the type, or {@code null} if not known.
*
The default implementations returns {@code null}.
*/
@Nullable
default Object getSource() {
return null;
}
}
/**
* {@link Serializable} {@link InvocationHandler} used by the proxied {@link Type}.
* Provides serialization support and enhances any methods that return {@code Type}
* or {@code Type[]}.
*/
@SuppressWarnings("serial")
private static class TypeProxyInvocationHandler implements InvocationHandler, Serializable {
private final TypeProvider provider;
public TypeProxyInvocationHandler(TypeProvider provider) {
this.provider = provider;
}
@Override
@Nullable
public Object invoke(Object proxy, Method method, @Nullable Object[] args) throws Throwable {
if (method.getName().equals("equals") && args != null) {
Object other = args[0];
// Unwrap proxies for speed
if (other instanceof Type) {
other = unwrap((Type) other);
}
return ObjectUtils.nullSafeEquals(this.provider.getType(), other);
}
else if (method.getName().equals("hashCode")) {
return ObjectUtils.nullSafeHashCode(this.provider.getType());
}
else if (method.getName().equals("getTypeProvider")) {
return this.provider;
}
if (Type.class == method.getReturnType() && args == null) {
return forTypeProvider(new MethodInvokeTypeProvider(this.provider, method, -1));
}
else if (Type[].class == method.getReturnType() && args == null) {
Type[] result = new Type[((Type[]) method.invoke(this.provider.getType())).length];
for (int i = 0; i < result.length; i++) {
result[i] = forTypeProvider(new MethodInvokeTypeProvider(this.provider, method, i));
}
return result;
}
try {
return method.invoke(this.provider.getType(), args);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
/**
* {@link TypeProvider} for {@link Type Types} obtained from a {@link Field}.
*/
@SuppressWarnings("serial")
static class FieldTypeProvider implements TypeProvider {
private final String fieldName;
private final Class declaringClass;
private transient Field field;
public FieldTypeProvider(Field field) {
this.fieldName = field.getName();
this.declaringClass = field.getDeclaringClass();
this.field = field;
}
@Override
public Type getType() {
return this.field.getGenericType();
}
@Override
public Object getSource() {
return this.field;
}
private void readObject(ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
inputStream.defaultReadObject();
try {
this.field = this.declaringClass.getDeclaredField(this.fieldName);
}
catch (Throwable ex) {
throw new IllegalStateException("Could not find original class structure", ex);
}
}
}
/**
* {@link TypeProvider} for {@link Type Types} obtained from a {@link MethodParameter}.
*/
@SuppressWarnings("serial")
static class MethodParameterTypeProvider implements TypeProvider {
@Nullable
private final String methodName;
private final Class[] parameterTypes;
private final Class declaringClass;
private final int parameterIndex;
private transient MethodParameter methodParameter;
public MethodParameterTypeProvider(MethodParameter methodParameter) {
this.methodName = (methodParameter.getMethod() != null ? methodParameter.getMethod().getName() : null);
this.parameterTypes = methodParameter.getExecutable().getParameterTypes();
this.declaringClass = methodParameter.getDeclaringClass();
this.parameterIndex = methodParameter.getParameterIndex();
this.methodParameter = methodParameter;
}
@Override
public Type getType() {
return this.methodParameter.getGenericParameterType();
}
@Override
public Object getSource() {
return this.methodParameter;
}
private void readObject(ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
inputStream.defaultReadObject();
try {
if (this.methodName != null) {
this.methodParameter = new MethodParameter(
this.declaringClass.getDeclaredMethod(this.methodName, this.parameterTypes), this.parameterIndex);
}
else {
this.methodParameter = new MethodParameter(
this.declaringClass.getDeclaredConstructor(this.parameterTypes), this.parameterIndex);
}
}
catch (Throwable ex) {
throw new IllegalStateException("Could not find original class structure", ex);
}
}
}
/**
* {@link TypeProvider} for {@link Type Types} obtained by invoking a no-arg method.
*/
@SuppressWarnings("serial")
static class MethodInvokeTypeProvider implements TypeProvider {
private final TypeProvider provider;
private final String methodName;
private final Class declaringClass;
private final int index;
private transient Method method;
@Nullable
private transient volatile Object result;
public MethodInvokeTypeProvider(TypeProvider provider, Method method, int index) {
this.provider = provider;
this.methodName = method.getName();
this.declaringClass = method.getDeclaringClass();
this.index = index;
this.method = method;
}
@Override
@Nullable
public Type getType() {
Object result = this.result;
if (result == null) {
// Lazy invocation of the target method on the provided type
result = ReflectionUtils.invokeMethod(this.method, this.provider.getType());
// Cache the result for further calls to getType()
this.result = result;
}
return (result instanceof Type[] ? ((Type[]) result)[this.index] : (Type) result);
}
@Override
@Nullable
public Object getSource() {
return null;
}
private void readObject(ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
inputStream.defaultReadObject();
Method method = ReflectionUtils.findMethod(this.declaringClass, this.methodName);
if (method == null) {
throw new IllegalStateException("Cannot find method on deserialization: " + this.methodName);
}
if (method.getReturnType() != Type.class && method.getReturnType() != Type[].class) {
throw new IllegalStateException(
"Invalid return type on deserialized method - needs to be Type or Type[]: " + method);
}
this.method = method;
}
}
}