forked from resilience4j/resilience4j
-
-
Notifications
You must be signed in to change notification settings - Fork 0
/
FallbackDecorator.java
81 lines (71 loc) · 2.7 KB
/
FallbackDecorator.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
/*
*
* Copyright 2018
*
* 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 io.github.resilience4j.feign;
import static java.util.Objects.requireNonNull;
import java.lang.reflect.Method;
import feign.InvocationHandlerFactory.MethodHandler;
import feign.Target;
import io.vavr.CheckedFunction1;
/**
* Decorator that calls a fallback in the case that an exception is thrown.
*/
class FallbackDecorator<T> implements FeignDecorator {
private final T fallback;
public FallbackDecorator(T fallback) {
this.fallback = requireNonNull(fallback, "Fallback cannot be null!");
}
/**
* Calls the fallback if the invocationCall throws an {@link Exception}.
*
* @throws IllegalArgumentException if the fallback object does not have a corresponding
* fallback method.
*/
@Override
public CheckedFunction1<Object[], Object> decorate(CheckedFunction1<Object[], Object> invocationCall,
Method method,
MethodHandler methodHandler,
Target<?> target) {
final Method fallbackMethod;
validateFallback(method);
fallbackMethod = getFallbackMethod(method);
return args -> {
try {
return invocationCall.apply(args);
} catch (final Exception exception) {
return fallbackMethod.invoke(fallback, args);
}
};
}
private void validateFallback(Method method) {
if (fallback.getClass().isAssignableFrom(method.getDeclaringClass())) {
throw new IllegalArgumentException("Cannot use the fallback ["
+ fallback.getClass() + "] for ["
+ method.getDeclaringClass() + "]!");
}
}
private Method getFallbackMethod(Method method) {
Method fallbackMethod;
try {
fallbackMethod = fallback.getClass().getMethod(method.getName(), method.getParameterTypes());
} catch (NoSuchMethodException | SecurityException e) {
throw new IllegalArgumentException("Cannot use the fallback ["
+ fallback.getClass() + "] for ["
+ method.getDeclaringClass() + "]", e);
}
return fallbackMethod;
}
}