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/**
* Copyright 2012-2021 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 static feign.Util.checkArgument;
import static feign.Util.checkNotNull;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.*;
import java.util.Map.Entry;
import feign.InvocationHandlerFactory.MethodHandler;
import feign.Param.Expander;
import feign.Request.Options;
import feign.codec.*;
import feign.template.UriUtils;
public class ReflectiveFeign extends Feign {
private final ParseHandlersByName targetToHandlersByName;
private final InvocationHandlerFactory factory;
private final QueryMapEncoder queryMapEncoder;
ReflectiveFeign(ParseHandlersByName targetToHandlersByName, InvocationHandlerFactory factory,
QueryMapEncoder queryMapEncoder) {
this.targetToHandlersByName = targetToHandlersByName;
this.factory = factory;
this.queryMapEncoder = queryMapEncoder;
}
/**
* creates an api binding to the {@code target}. As this invokes reflection, care should be taken
* to cache the result.
*/
// 返回代理类
@SuppressWarnings("unchecked")
@Override
public <T> T newInstance(Target<T> target) {
// 解析注解
Map<String, MethodHandler> nameToHandler = targetToHandlersByName.apply(target);
Map<Method, MethodHandler> methodToHandler = new LinkedHashMap<Method, MethodHandler>();
List<DefaultMethodHandler> defaultMethodHandlers = new LinkedList<DefaultMethodHandler>();
// 遍历代理目标的方法
for (Method method : target.type().getMethods()) {
if (method.getDeclaringClass() == Object.class) {
continue;
} else if (Util.isDefault(method)) {
DefaultMethodHandler handler = new DefaultMethodHandler(method);
defaultMethodHandlers.add(handler);
methodToHandler.put(method, handler);
} else {
// 接口代理走这里
methodToHandler.put(method, nameToHandler.get(Feign.configKey(target.type(), method)));
}
}
// 调用feign.InvocationHandlerFactory.Default 的create
InvocationHandler handler = factory.create(target, methodToHandler);
T proxy = (T) Proxy.newProxyInstance(target.type().getClassLoader(),
new Class<?>[] {target.type()}, handler);
for (DefaultMethodHandler defaultMethodHandler : defaultMethodHandlers) {
// 所有方法绑定同一个代理，由同个代理分发
defaultMethodHandler.bindTo(proxy);
}
return proxy;
}
static class FeignInvocationHandler implements InvocationHandler {
private final Target target;
private final Map<Method, MethodHandler> dispatch;
FeignInvocationHandler(Target target, Map<Method, MethodHandler> dispatch) {
this.target = checkNotNull(target, "target");
this.dispatch = checkNotNull(dispatch, "dispatch for %s", target);
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// equals、hash和toString进行特殊处理
if ("equals".equals(method.getName())) {
try {
Object otherHandler =
args.length > 0 && args[0] != null ? Proxy.getInvocationHandler(args[0]) : null;
return equals(otherHandler);
} catch (IllegalArgumentException e) {
return false;
}
} else if ("hashCode".equals(method.getName())) {
return hashCode();
} else if ("toString".equals(method.getName())) {
return toString();
}
// invoke
return dispatch.get(method).invoke(args);
}
@Override
public boolean equals(Object obj) {
if (obj instanceof FeignInvocationHandler) {
FeignInvocationHandler other = (FeignInvocationHandler) obj;
return target.equals(other.target);
}
return false;
}
@Override
public int hashCode() {
return target.hashCode();
}
@Override
public String toString() {
return target.toString();
}
}
static final class ParseHandlersByName {
private final Contract contract;
private final Options options;
private final Encoder encoder;
private final Decoder decoder;
private final ErrorDecoder errorDecoder;
private final QueryMapEncoder queryMapEncoder;
private final SynchronousMethodHandler.Factory factory;
ParseHandlersByName(
Contract contract,
Options options,
Encoder encoder,
Decoder decoder,
QueryMapEncoder queryMapEncoder,
ErrorDecoder errorDecoder,
SynchronousMethodHandler.Factory factory) {
this.contract = contract;
this.options = options;
this.factory = factory;
this.errorDecoder = errorDecoder;
this.queryMapEncoder = queryMapEncoder;
this.encoder = checkNotNull(encoder, "encoder");
this.decoder = checkNotNull(decoder, "decoder");
}
public Map<String, MethodHandler> apply(Target target) {
// 注解触点解析 出注解元数据，可用spring触点
List<MethodMetadata> metadata = contract.parseAndValidateMetadata(target.type());
Map<String, MethodHandler> result = new LinkedHashMap<String, MethodHandler>();
for (MethodMetadata md : metadata) {
BuildTemplateByResolvingArgs buildTemplate;
if (!md.formParams().isEmpty() && md.template().bodyTemplate() == null) {
buildTemplate =
new BuildFormEncodedTemplateFromArgs(md, encoder, queryMapEncoder, target);
} else if (md.bodyIndex() != null || md.alwaysEncodeBody()) {
buildTemplate = new BuildEncodedTemplateFromArgs(md, encoder, queryMapEncoder, target);
} else {
buildTemplate = new BuildTemplateByResolvingArgs(md, queryMapEncoder, target);
}
if (md.isIgnored()) {
result.put(md.configKey(), args -> {
throw new IllegalStateException(md.configKey() + " is not a method handled by feign");
});
} else {
// 代理和key的映射
result.put(md.configKey(),
factory.create(target, md, buildTemplate, options, decoder, errorDecoder));
}
}
return result;
}
}
private static class BuildTemplateByResolvingArgs implements RequestTemplate.Factory {
private final QueryMapEncoder queryMapEncoder;
protected final MethodMetadata metadata;
protected final Target<?> target;
private final Map<Integer, Expander> indexToExpander = new LinkedHashMap<Integer, Expander>();
private BuildTemplateByResolvingArgs(MethodMetadata metadata, QueryMapEncoder queryMapEncoder,
Target target) {
this.metadata = metadata;
this.target = target;
this.queryMapEncoder = queryMapEncoder;
if (metadata.indexToExpander() != null) {
indexToExpander.putAll(metadata.indexToExpander());
return;
}
if (metadata.indexToExpanderClass().isEmpty()) {
return;
}
for (Entry<Integer, Class<? extends Expander>> indexToExpanderClass : metadata
.indexToExpanderClass().entrySet()) {
try {
indexToExpander
.put(indexToExpanderClass.getKey(), indexToExpanderClass.getValue().newInstance());
} catch (InstantiationException e) {
throw new IllegalStateException(e);
} catch (IllegalAccessException e) {
throw new IllegalStateException(e);
}
}
}
@Override
public RequestTemplate create(Object[] argv) {
// 构建请求模板
RequestTemplate mutable = RequestTemplate.from(metadata.template());
mutable.feignTarget(target);
if (metadata.urlIndex() != null) {
int urlIndex = metadata.urlIndex();
checkArgument(argv[urlIndex] != null, "URI parameter %s was null", urlIndex);
mutable.target(String.valueOf(argv[urlIndex]));
}
Map<String, Object> varBuilder = new LinkedHashMap<String, Object>();
for (Entry<Integer, Collection<String>> entry : metadata.indexToName().entrySet()) {
int i = entry.getKey();
Object value = argv[entry.getKey()];
if (value != null) { // Null values are skipped.
if (indexToExpander.containsKey(i)) {
value = expandElements(indexToExpander.get(i), value);
}
for (String name : entry.getValue()) {
varBuilder.put(name, value);
}
}
}
RequestTemplate template = resolve(argv, mutable, varBuilder);
if (metadata.queryMapIndex() != null) {
// add query map parameters after initial resolve so that they take
// precedence over any predefined values
Object value = argv[metadata.queryMapIndex()];
Map<String, Object> queryMap = toQueryMap(value);
template = addQueryMapQueryParameters(queryMap, template);
}
if (metadata.headerMapIndex() != null) {
template =
addHeaderMapHeaders((Map<String, Object>) argv[metadata.headerMapIndex()], template);
}
return template;
}
private Map<String, Object> toQueryMap(Object value) {
if (value instanceof Map) {
return (Map<String, Object>) value;
}
try {
return queryMapEncoder.encode(value);
} catch (EncodeException e) {
throw new IllegalStateException(e);
}
}
private Object expandElements(Expander expander, Object value) {
if (value instanceof Iterable) {
return expandIterable(expander, (Iterable) value);
}
return expander.expand(value);
}
private List<String> expandIterable(Expander expander, Iterable value) {
List<String> values = new ArrayList<String>();
for (Object element : value) {
if (element != null) {
values.add(expander.expand(element));
}
}
return values;
}
@SuppressWarnings("unchecked")
private RequestTemplate addHeaderMapHeaders(Map<String, Object> headerMap,
RequestTemplate mutable) {
for (Entry<String, Object> currEntry : headerMap.entrySet()) {
Collection<String> values = new ArrayList<String>();
Object currValue = currEntry.getValue();
if (currValue instanceof Iterable<?>) {
Iterator<?> iter = ((Iterable<?>) currValue).iterator();
while (iter.hasNext()) {
Object nextObject = iter.next();
values.add(nextObject == null ? null : nextObject.toString());
}
} else {
values.add(currValue == null ? null : currValue.toString());
}
mutable.header(currEntry.getKey(), values);
}
return mutable;
}
@SuppressWarnings("unchecked")
private RequestTemplate addQueryMapQueryParameters(Map<String, Object> queryMap,
RequestTemplate mutable) {
for (Entry<String, Object> currEntry : queryMap.entrySet()) {
Collection<String> values = new ArrayList<String>();
boolean encoded = metadata.queryMapEncoded();
Object currValue = currEntry.getValue();
if (currValue instanceof Iterable<?>) {
Iterator<?> iter = ((Iterable<?>) currValue).iterator();
while (iter.hasNext()) {
Object nextObject = iter.next();
values.add(nextObject == null ? null
: encoded ? nextObject.toString()
: UriUtils.encode(nextObject.toString()));
}
} else if (currValue instanceof Object[]) {
for (Object value : (Object[]) currValue) {
values.add(value == null ? null
: encoded ? value.toString() : UriUtils.encode(value.toString()));
}
} else {
values.add(currValue == null ? null
: encoded ? currValue.toString() : UriUtils.encode(currValue.toString()));
}
mutable.query(encoded ? currEntry.getKey() : UriUtils.encode(currEntry.getKey()), values);
}
return mutable;
}
protected RequestTemplate resolve(Object[] argv,
RequestTemplate mutable,
Map<String, Object> variables) {
return mutable.resolve(variables);
}
}
private static class BuildFormEncodedTemplateFromArgs extends BuildTemplateByResolvingArgs {
private final Encoder encoder;
private BuildFormEncodedTemplateFromArgs(MethodMetadata metadata, Encoder encoder,
QueryMapEncoder queryMapEncoder, Target target) {
super(metadata, queryMapEncoder, target);
this.encoder = encoder;
}
@Override
protected RequestTemplate resolve(Object[] argv,
RequestTemplate mutable,
Map<String, Object> variables) {
Map<String, Object> formVariables = new LinkedHashMap<String, Object>();
for (Entry<String, Object> entry : variables.entrySet()) {
if (metadata.formParams().contains(entry.getKey())) {
formVariables.put(entry.getKey(), entry.getValue());
}
}
try {
encoder.encode(formVariables, Encoder.MAP_STRING_WILDCARD, mutable);
} catch (EncodeException e) {
throw e;
} catch (RuntimeException e) {
throw new EncodeException(e.getMessage(), e);
}
return super.resolve(argv, mutable, variables);
}
}
private static class BuildEncodedTemplateFromArgs extends BuildTemplateByResolvingArgs {
private final Encoder encoder;
private BuildEncodedTemplateFromArgs(MethodMetadata metadata, Encoder encoder,
QueryMapEncoder queryMapEncoder, Target target) {
super(metadata, queryMapEncoder, target);
this.encoder = encoder;
}
@Override
protected RequestTemplate resolve(Object[] argv,
RequestTemplate mutable,
Map<String, Object> variables) {
boolean alwaysEncodeBody = mutable.methodMetadata().alwaysEncodeBody();
Object body = null;
if (!alwaysEncodeBody) {
body = argv[metadata.bodyIndex()];
checkArgument(body != null, "Body parameter %s was null", metadata.bodyIndex());
}
try {
if (alwaysEncodeBody) {
body = argv == null ? new Object[0] : argv;
encoder.encode(body, Object[].class, mutable);
} else {
encoder.encode(body, metadata.bodyType(), mutable);
}
} catch (EncodeException e) {
throw e;
} catch (RuntimeException e) {
throw new EncodeException(e.getMessage(), e);
}
return super.resolve(argv, mutable, variables);
}
}
}