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Contract.java
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/*
* Copyright 2013 Netflix, Inc.
*
* 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 javax.inject.Named;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import static feign.Util.checkState;
import static feign.Util.emptyToNull;
import static feign.Util.resolveLastTypeParameter;
/**
* Defines what annotations and values are valid on interfaces.
*/
public abstract class Contract {
/**
* Called to parse the methods in the class that are linked to HTTP requests.
*/
public List<MethodMetadata> parseAndValidatateMetadata(Class<?> declaring) {
List<MethodMetadata> metadata = new ArrayList<MethodMetadata>();
for (Method method : declaring.getDeclaredMethods()) {
if (method.getDeclaringClass() == Object.class)
continue;
metadata.add(parseAndValidatateMetadata(method));
}
return metadata;
}
/**
* Called indirectly by {@link #parseAndValidatateMetadata(Class)}.
*/
public MethodMetadata parseAndValidatateMetadata(Method method) {
MethodMetadata data = new MethodMetadata();
data.decodeInto(method.getGenericReturnType());
data.configKey(Feign.configKey(method));
for (Annotation methodAnnotation : method.getAnnotations()) {
processAnnotationOnMethod(data, methodAnnotation, method);
}
checkState(data.template().method() != null, "Method %s not annotated with HTTP method type (ex. GET, POST)",
method.getName());
Class<?>[] parameterTypes = method.getParameterTypes();
Annotation[][] parameterAnnotations = method.getParameterAnnotations();
int count = parameterAnnotations.length;
for (int i = 0; i < count; i++) {
boolean isHttpAnnotation = false;
if (parameterAnnotations[i] != null) {
isHttpAnnotation = processAnnotationsOnParameter(data, parameterAnnotations[i], i);
}
if (parameterTypes[i] == URI.class) {
data.urlIndex(i);
} else if (IncrementalCallback.class.isAssignableFrom(parameterTypes[i])) {
checkState(method.getReturnType() == void.class, "IncrementalCallback methods must return void: %s", method);
checkState(i == count - 1, "IncrementalCallback must be the last parameter: %s", method);
Type context = method.getGenericParameterTypes()[i];
Type incrementalCallbackType = resolveLastTypeParameter(context, IncrementalCallback.class);
data.decodeInto(incrementalCallbackType);
data.incrementalCallbackIndex(i);
checkState(incrementalCallbackType != null, "Expected param %s to be IncrementalCallback<X> or IncrementalCallback<? super X> or a subtype",
context, incrementalCallbackType);
} else if (!isHttpAnnotation) {
checkState(data.formParams().isEmpty(), "Body parameters cannot be used with form parameters.");
checkState(data.bodyIndex() == null, "Method has too many Body parameters: %s", method);
data.bodyIndex(i);
data.bodyType(method.getGenericParameterTypes()[i]);
}
}
return data;
}
/**
* @param data metadata collected so far relating to the current java method.
* @param annotation annotations present on the current method annotation.
* @param method method currently being processed.
*/
protected abstract void processAnnotationOnMethod(MethodMetadata data, Annotation annotation, Method method);
/**
* @param data metadata collected so far relating to the current java method.
* @param annotations annotations present on the current parameter annotation.
* @param paramIndex if you find a name in {@code annotations}, call {@link #nameParam(MethodMetadata, String,
* int)} with this as the last parameter.
* @return true if you called {@link #nameParam(MethodMetadata, String, int)} after finding an http-relevant
* annotation.
*/
protected abstract boolean processAnnotationsOnParameter(MethodMetadata data, Annotation[] annotations, int paramIndex);
protected Collection<String> addTemplatedParam(Collection<String> possiblyNull, String name) {
if (possiblyNull == null)
possiblyNull = new ArrayList<String>();
possiblyNull.add(String.format("{%s}", name));
return possiblyNull;
}
/**
* links a parameter name to its index in the method signature.
*/
protected void nameParam(MethodMetadata data, String name, int i) {
Collection<String> names = data.indexToName().containsKey(i) ? data.indexToName().get(i) : new ArrayList<String>();
names.add(name);
data.indexToName().put(i, names);
}
static class Default extends Contract {
@Override
protected void processAnnotationOnMethod(MethodMetadata data, Annotation methodAnnotation, Method method) {
Class<? extends Annotation> annotationType = methodAnnotation.annotationType();
if (annotationType == RequestLine.class) {
String requestLine = RequestLine.class.cast(methodAnnotation).value();
checkState(emptyToNull(requestLine) != null, "RequestLine annotation was empty on method %s.", method.getName());
if (requestLine.indexOf(' ') == -1) {
data.template().method(requestLine);
return;
}
data.template().method(requestLine.substring(0, requestLine.indexOf(' ')));
if (requestLine.indexOf(' ') == requestLine.lastIndexOf(' ')) {
// no HTTP version is ok
data.template().append(requestLine.substring(requestLine.indexOf(' ') + 1));
} else {
// skip HTTP version
data.template().append(requestLine.substring(requestLine.indexOf(' ') + 1, requestLine.lastIndexOf(' ')));
}
} else if (annotationType == Body.class) {
String body = Body.class.cast(methodAnnotation).value();
checkState(emptyToNull(body) != null, "Body annotation was empty on method %s.", method.getName());
if (body.indexOf('{') == -1) {
data.template().body(body);
} else {
data.template().bodyTemplate(body);
}
} else if (annotationType == Headers.class) {
String[] headersToParse = Headers.class.cast(methodAnnotation).value();
checkState(headersToParse.length > 0, "Headers annotation was empty on method %s.", method.getName());
for (String header : headersToParse) {
int colon = header.indexOf(':');
data.template().header(header.substring(0, colon), header.substring(colon + 2));
}
}
}
@Override
protected boolean processAnnotationsOnParameter(MethodMetadata data, Annotation[] annotations, int paramIndex) {
boolean isHttpAnnotation = false;
for (Annotation parameterAnnotation : annotations) {
Class<? extends Annotation> annotationType = parameterAnnotation.annotationType();
if (annotationType == Named.class) {
String name = Named.class.cast(parameterAnnotation).value();
checkState(emptyToNull(name) != null, "Named annotation was empty on param %s.", paramIndex);
nameParam(data, name, paramIndex);
isHttpAnnotation = true;
if (data.template().url().indexOf('{' + name + '}') == -1 && //
!(data.template().queries().containsKey(name)
|| data.template().headers().containsKey(name))) {
data.formParams().add(name);
}
}
}
return isHttpAnnotation;
}
}
}