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ReflectiveAsyncFeign.java
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137 lines (115 loc) · 4.5 KB
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/**
* Copyright 2012-2020 The Feign 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
*
* 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 feign;
import java.lang.reflect.*;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ConcurrentHashMap;
@Experimental
public class ReflectiveAsyncFeign<C> extends AsyncFeign<C> {
private class AsyncFeignInvocationHandler<T> implements InvocationHandler {
private final Map<Method, MethodInfo> methodInfoLookup = new ConcurrentHashMap<>();
private final Class<T> type;
private final T instance;
private final C context;
AsyncFeignInvocationHandler(Class<T> type, T instance, C context) {
this.type = type;
this.instance = instance;
this.context = context;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if ("equals".equals(method.getName()) && method.getParameterCount() == 1) {
try {
final Object otherHandler =
args.length > 0 && args[0] != null ? Proxy.getInvocationHandler(args[0])
: null;
return equals(otherHandler);
} catch (final IllegalArgumentException e) {
return false;
}
} else if ("hashCode".equals(method.getName()) && method.getParameterCount() == 0) {
return hashCode();
} else if ("toString".equals(method.getName()) && method.getParameterCount() == 0) {
return toString();
}
final MethodInfo methodInfo =
methodInfoLookup.computeIfAbsent(method, m -> new MethodInfo(type, m));
setInvocationContext(new AsyncInvocation<C>(context, methodInfo));
try {
return method.invoke(instance, args);
} catch (final InvocationTargetException e) {
Throwable cause = e.getCause();
if (cause instanceof AsyncJoinException) {
cause = cause.getCause();
}
throw cause;
} finally {
clearInvocationContext();
}
}
@SuppressWarnings("unchecked")
@Override
public boolean equals(Object obj) {
if (obj instanceof AsyncFeignInvocationHandler) {
final AsyncFeignInvocationHandler<?> other = (AsyncFeignInvocationHandler<?>) obj;
return instance.equals(other.instance);
}
return false;
}
@Override
public int hashCode() {
return instance.hashCode();
}
@Override
public String toString() {
return instance.toString();
}
}
public ReflectiveAsyncFeign(AsyncBuilder<C> asyncBuilder) {
super(asyncBuilder);
}
private String getFullMethodName(Class<?> type, Type retType, Method m) {
return retType.getTypeName() + " " + type.toGenericString() + "." + m.getName();
}
@Override
protected <T> T wrap(Class<T> type, T instance, C context) {
if (!type.isInterface()) {
throw new IllegalArgumentException("Type must be an interface: " + type);
}
for (final Method m : type.getMethods()) {
final Class<?> retType = m.getReturnType();
if (!CompletableFuture.class.isAssignableFrom(retType)) {
continue; // synchronous case
}
if (retType != CompletableFuture.class) {
throw new IllegalArgumentException("Method return type is not CompleteableFuture: "
+ getFullMethodName(type, retType, m));
}
final Type genRetType = m.getGenericReturnType();
if (!ParameterizedType.class.isInstance(genRetType)) {
throw new IllegalArgumentException("Method return type is not parameterized: "
+ getFullMethodName(type, genRetType, m));
}
if (WildcardType.class
.isInstance(ParameterizedType.class.cast(genRetType).getActualTypeArguments()[0])) {
throw new IllegalArgumentException(
"Wildcards are not supported for return-type parameters: "
+ getFullMethodName(type, genRetType, m));
}
}
return type.cast(Proxy.newProxyInstance(type.getClassLoader(), new Class<?>[] {type},
new AsyncFeignInvocationHandler<>(type, instance, context)));
}
}