Feign单独使用时，可以对配置的静态服务发起Http调用；当Feign结合Ribbon时，对配置的静态服务可以根据负载均衡策略进行调用；再结合Eureka，可以配合注册中心以及负载均衡策略动态发起调用。本篇分析Feign对配置的静态服务是如何发起Http调用的
一、 Maven依赖
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Greenwich.SR3</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
二 、自动配置类
Feign中的自动配置类是FeignAutoConfiguration，例举出其中重要的两个Bean
- FeignContext
- Targeter
FeignContext内部还有内置配置类FeignClientsConfiguration，这是创建服务提供方IOC容器时会被解析的配置类，例举出几个重要的Bean - Decoder
- Encoder
- Feign.Builder
- FeignLoggerFactory
- Contract
三、 Bean释义
- FeignContext
托管给容器的一个Bean，在以服务提供方为维度初始化子容器时会被使用到
@Bean
public FeignContext feignContext() {
FeignContext context = new FeignContext();
context.setConfigurations(this.configurations);
return context;
}
- Targeter
用以生成Fiegn代理类
@Bean
@ConditionalOnMissingBean
public Targeter feignTargeter() {
return new HystrixTargeter();
}
服务提供方维度的Bean
- Decoder
编码器，用以对请求的参数做编码
@Bean
@ConditionalOnMissingBean
public Decoder feignDecoder() {
return new OptionalDecoder(
new ResponseEntityDecoder(new SpringDecoder(this.messageConverters)));
}
- Encoder
解码器，用以对服务端的响应做解码
@Bean
@ConditionalOnMissingBean
@ConditionalOnMissingClass("org.springframework.data.domain.Pageable")
public Encoder feignEncoder() {
return new SpringEncoder(this.messageConverters);
}
- Retryer
重试策略，默认不重试
@Bean
@ConditionalOnMissingBean
public Retryer feignRetryer() {
return Retryer.NEVER_RETRY;
}
- Builder
用以封装FeignClient上所有配置信息
@Bean
@Scope("prototype")
@ConditionalOnMissingBean
public Feign.Builder feignBuilder(Retryer retryer) {
return Feign.builder().retryer(retryer);
}
- Contract
以类似于SpringMvc约定的参数格式来解析FeignClient接口的参数
@Bean
@ConditionalOnMissingBean
public Contract feignContract(ConversionService feignConversionService) {
return new SpringMvcContract(this.parameterProcessors, feignConversionService);
}
关于Feign的使用在官网有介绍：需要建立合适的FeignClient，配置好静态服务的节点信息，最终使用注解开启Feign功能。然后便可以用方法调用的形式来代替传统编写Http请求的步骤，极大简化了开发过程。而关于整个Feign可以分为开启与使用两步，开启：对配置的服务提供方资源进行收集并创建代理类；使用：当调用方法是，交由实际创建的代理类来请求服务提供方的资源
四 、FeignClient类收集
Feign的开启需要使用注解@EnableFeignClients，这也是整个Feign的入口
- 在能被容器扫描的类上配置注解@EnableFeignClients后，启动服务
- Spring处理该类时，会从类上注解中收集导入的ImportBeanDefinitionRegistrar，随后调用它们的registerBeanDefinitions方法
- @EnableFeignClients上导入的类是FeignClientsRegistrar
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(FeignClientsRegistrar.class)
public @interface EnableFeignClients {
日常使用中，一个FeignClient类对应于一个服务，类中不同的方法对应与服务中不同的接口。这样配置之后，对不同类不同方法的调用，可以达到对不同服务不同接口的发起Http调用。
- 在FeignClientsRegistrar的registerBeanDefinitions方法中，分别为注册默认配置类和注册FeignClient类
- 在registerFeignClients中注册FeignClient类
- 使用容器的Scanner，配合注解类型过滤器，从配置的或者默认的路径中，扫描出带有注解@FeignClient的类形成BeanDefinition
- 在registerFeignClient中尝试将这些BeanDefinition注册到容器中
- 在构造BeanDefinitionBuilder时，属性contextId实际是@FeignClient注解上配置的value或者name属性，用以区分服务提供方，BeanDefinitionBuilder持有的BeanDefinition的BeanClass已经被设置为FeignClientFactoryBean（这是一个FactoryBean，在Bean需要往容器托管时，其getObject方法会被调用），最后构造完成后注册到容器中。
@Override
public void registerBeanDefinitions(AnnotationMetadata metadata,
BeanDefinitionRegistry registry) {
registerDefaultConfiguration(metadata, registry);
registerFeignClients(metadata, registry);
}
public void registerFeignClients(AnnotationMetadata metadata,
BeanDefinitionRegistry registry) {
ClassPathScanningCandidateComponentProvider scanner = getScanner();
scanner.setResourceLoader(this.resourceLoader);
Set<String> basePackages;
Map<String, Object> attrs = metadata
.getAnnotationAttributes(EnableFeignClients.class.getName());
AnnotationTypeFilter annotationTypeFilter = new AnnotationTypeFilter(
FeignClient.class);
final Class<?>[] clients = attrs == null ? null
: (Class<?>[]) attrs.get("clients");
if (clients == null || clients.length == 0) {
scanner.addIncludeFilter(annotationTypeFilter);
basePackages = getBasePackages(metadata);
}
else {
final Set<String> clientClasses = new HashSet<>();
basePackages = new HashSet<>();
for (Class<?> clazz : clients) {
basePackages.add(ClassUtils.getPackageName(clazz));
clientClasses.add(clazz.getCanonicalName());
}
AbstractClassTestingTypeFilter filter = new AbstractClassTestingTypeFilter() {
@Override
protected boolean match(ClassMetadata metadata) {
String cleaned = metadata.getClassName().replaceAll("\\$", ".");
return clientClasses.contains(cleaned);
}
};
scanner.addIncludeFilter(
new AllTypeFilter(Arrays.asList(filter, annotationTypeFilter)));
}
for (String basePackage : basePackages) {
Set<BeanDefinition> candidateComponents = scanner
.findCandidateComponents(basePackage);
for (BeanDefinition candidateComponent : candidateComponents) {
if (candidateComponent instanceof AnnotatedBeanDefinition) {
// verify annotated class is an interface
AnnotatedBeanDefinition beanDefinition = (AnnotatedBeanDefinition) candidateComponent;
AnnotationMetadata annotationMetadata = beanDefinition.getMetadata();
Assert.isTrue(annotationMetadata.isInterface(),
"@FeignClient can only be specified on an interface");
Map<String, Object> attributes = annotationMetadata
.getAnnotationAttributes(
FeignClient.class.getCanonicalName());
String name = getClientName(attributes);
registerClientConfiguration(registry, name,
attributes.get("configuration"));
registerFeignClient(registry, annotationMetadata, attributes);
}
}
}
}
private void registerFeignClient(BeanDefinitionRegistry registry,
AnnotationMetadata annotationMetadata, Map<String, Object> attributes) {
String className = annotationMetadata.getClassName();
BeanDefinitionBuilder definition = BeanDefinitionBuilder
.genericBeanDefinition(FeignClientFactoryBean.class);
validate(attributes);
definition.addPropertyValue("url", getUrl(attributes));
definition.addPropertyValue("path", getPath(attributes));
String name = getName(attributes);
definition.addPropertyValue("name", name);
String contextId = getContextId(attributes);
definition.addPropertyValue("contextId", contextId);
definition.addPropertyValue("type", className);
definition.addPropertyValue("decode404", attributes.get("decode404"));
definition.addPropertyValue("fallback", attributes.get("fallback"));
definition.addPropertyValue("fallbackFactory", attributes.get("fallbackFactory"));
definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);
String alias = contextId + "FeignClient";
AbstractBeanDefinition beanDefinition = definition.getBeanDefinition();
boolean primary = (Boolean) attributes.get("primary"); // has a default, won't be
// null
beanDefinition.setPrimary(primary);
String qualifier = getQualifier(attributes);
if (StringUtils.hasText(qualifier)) {
alias = qualifier;
}
BeanDefinitionHolder holder = new BeanDefinitionHolder(beanDefinition, className,
new String[] { alias });
BeanDefinitionReaderUtils.registerBeanDefinition(holder, registry);
}
五 创建服务提供方IOC容器
FeignClientFactoryBean与FeignClient具有对应关系，一个FeignClient对应一个FeignClientFactoryBean（FeignClient上配置的name或value唯一），FeignClientFactoryBean有实现接口ApplicationContextAware，所以在回调方法中设置了属性applicationContext
- 在FeignClientFactoryBean的getObject方法中，实际调用的是getTarget
- 方法getTarget中首先从当前容器中获取FeignContext，也就是在自动配置类中托管的BeanFeignContext
- 方法feign中获取到Builder对象
- 以FeignClient上是否有配置url来决定启动负载均衡与否
- 对于配置了url的FeignClient（静态服务），在获取到Client与Targeter之后构造出代理对象。默认未配置Client，使用默认实现
@Override
public Object getObject() throws Exception {
return getTarget();
}
<T> T getTarget() {
FeignContext context = this.applicationContext.getBean(FeignContext.class);
Feign.Builder builder = feign(context);
if (!StringUtils.hasText(this.url)) {
if (!this.name.startsWith("http")) {
this.url = "http://" + this.name;
}
else {
this.url = this.name;
}
this.url += cleanPath();
return (T) loadBalance(builder, context,
new HardCodedTarget<>(this.type, this.name, this.url));
}
if (StringUtils.hasText(this.url) && !this.url.startsWith("http")) {
this.url = "http://" + this.url;
}
String url = this.url + cleanPath();
Client client = getOptional(context, Client.class);
if (client != null) {
if (client instanceof LoadBalancerFeignClient) {
// not load balancing because we have a url,
// but ribbon is on the classpath, so unwrap
client = ((LoadBalancerFeignClient) client).getDelegate();
}
builder.client(client);
}
Targeter targeter = get(context, Targeter.class);
return (T) targeter.target(this, builder, context,
new HardCodedTarget<>(this.type, this.name, url));
}
上述获取Builder 、Client 和Targeter并不是像获取FeignContext一样从当前容器中获取，而是从以服务提供方为维度的子IOC容器中获取，这点是和获取Ribbon配置的组件一样的流程
- 获取Builder调用了方法get
- 获取Client调用了方法getOptional
- 获取Targeter调用了方法get
- 但最终都是调用了context的getInstance方法
protected Feign.Builder feign(FeignContext context) {
FeignLoggerFactory loggerFactory = get(context, FeignLoggerFactory.class);
Logger logger = loggerFactory.create(this.type);
// @formatter:off
Feign.Builder builder = get(context, Feign.Builder.class)
// required values
.logger(logger)
.encoder(get(context, Encoder.class))
.decoder(get(context, Decoder.class))
.contract(get(context, Contract.class));
// @formatter:on
configureFeign(context, builder);
return builder;
}
protected <T> T get(FeignContext context, Class<T> type) {
T instance = context.getInstance(this.contextId, type);
if (instance == null) {
throw new IllegalStateException(
"No bean found of type " + type + " for " + this.contextId);
}
return instance;
}
protected <T> T getOptional(FeignContext context, Class<T> type) {
return context.getInstance(this.contextId, type);
}
protected <T> T get(FeignContext context, Class<T> type) {
T instance = context.getInstance(this.contextId, type);
if (instance == null) {
throw new IllegalStateException(
"No bean found of type " + type + " for " + this.contextId);
}
return instance;
}
获取实例的方法由FeignContext继承自父类NamedContextFactory
- 先尝试获取服务提供方的上下文
- 如果还未创建服务提供方上线文，尝试创建子IOC容器
- 容器类型为AnnotationConfigApplicationContext，并将FeignContext内置的配置类FeignClientsConfiguration以注册Bean的形式注册到容器中
- 在随后的refresh动作中，配置类上的配置的Bean会被加入到容器并实例化
public <T> T getInstance(String name, Class<T> type) {
AnnotationConfigApplicationContext context = getContext(name);
if (BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context,
type).length > 0) {
return context.getBean(type);
}
return null;
}
protected AnnotationConfigApplicationContext getContext(String name) {
if (!this.contexts.containsKey(name)) {
synchronized (this.contexts) {
if (!this.contexts.containsKey(name)) {
this.contexts.put(name, createContext(name));
}
}
}
return this.contexts.get(name);
}
protected AnnotationConfigApplicationContext createContext(String name) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
if (this.configurations.containsKey(name)) {
for (Class<?> configuration : this.configurations.get(name)
.getConfiguration()) {
context.register(configuration);
}
}
for (Map.Entry<String, C> entry : this.configurations.entrySet()) {
if (entry.getKey().startsWith("default.")) {
for (Class<?> configuration : entry.getValue().getConfiguration()) {
context.register(configuration);
}
}
}
context.register(PropertyPlaceholderAutoConfiguration.class,
this.defaultConfigType);
context.getEnvironment().getPropertySources().addFirst(new MapPropertySource(
this.propertySourceName,
Collections.<String, Object>singletonMap(this.propertyName, name)));
if (this.parent != null) {
// Uses Environment from parent as well as beans
context.setParent(this.parent);
// jdk11 issue
// https://github.com/spring-cloud/spring-cloud-netflix/issues/3101
context.setClassLoader(this.parent.getClassLoader());
}
context.setDisplayName(generateDisplayName(name));
context.refresh();
return context;
}
六 、为FeignClient创建代理类
待服务提供方上下文创建完成，FeignClientFactoryBean从上下文中获取到Builder、Client和Targeter后，开始创建代理类
- targeter是配置的BeanHystrixTargeter，封装了HardCodedTarget对象作为参数后，调用到Feign的内部类Builder的target方法
- 用调用方配置封装了Factory对象，这是SynchronousMethodHandler的内部类
- 用FeignClient的配置封装了ParseHandlersByName
- 最终再封装为ReflectiveFeign返回，封装时的invocationHandlerFactory是默认的InvocationHandlerFactory.Default
// FeignClientFactoryBean.getTarget
return (T) targeter.target(this, builder, context,
new HardCodedTarget<>(this.type, this.name, url));
// HystrixTargeter
@Override
public <T> T target(FeignClientFactoryBean factory, Feign.Builder feign,
FeignContext context, Target.HardCodedTarget<T> target) {
if (!(feign instanceof feign.hystrix.HystrixFeign.Builder)) {
return feign.target(target);
}
feign.hystrix.HystrixFeign.Builder builder = (feign.hystrix.HystrixFeign.Builder) feign;
SetterFactory setterFactory = getOptional(factory.getName(), context,
SetterFactory.class);
if (setterFactory != null) {
builder.setterFactory(setterFactory);
}
Class<?> fallback = factory.getFallback();
if (fallback != void.class) {
return targetWithFallback(factory.getName(), context, target, builder,
fallback);
}
Class<?> fallbackFactory = factory.getFallbackFactory();
if (fallbackFactory != void.class) {
return targetWithFallbackFactory(factory.getName(), context, target, builder,
fallbackFactory);
}
return feign.target(target);
}
public <T> T target(Target<T> target) {
return build().newInstance(target);
}
public Feign build() {
SynchronousMethodHandler.Factory synchronousMethodHandlerFactory =
new SynchronousMethodHandler.Factory(client, retryer, requestInterceptors, logger,
logLevel, decode404, closeAfterDecode, propagationPolicy);
ParseHandlersByName handlersByName =
new ParseHandlersByName(contract, options, encoder, decoder, queryMapEncoder,
errorDecoder, synchronousMethodHandlerFactory);
return new ReflectiveFeign(handlersByName, invocationHandlerFactory, queryMapEncoder);
}
创建代理类的过程是在ReflectiveFeign的newInstance中完成的
- 在封装的ParseHandlersByName中解析FeignClient类
- 使用配置的SpringMvc参数格式解析类来从FeignClient类中提取元数据，实际是由父类BaseContract完成
- 使用封装的SynchronousMethodHandler.Factory来创建FeignClient类中的方法对应的方法处理器MethodHandler（SynchronousMethodHandler）
- 将方法名与方法处理器的对应关系map返回
- 回到ReflectiveFeign中key看到将方法与方法处理器的映射关系保存在methodToHandler中
- 使用InvocationHandlerFactory.Default来创建代理类
- Default中最终创建的代理类是FeignInvocationHandler
@Override
public <T> T newInstance(Target<T> target) {
Map<String, MethodHandler> nameToHandler = targetToHandlersByName.apply(target);
Map<Method, MethodHandler> methodToHandler = new LinkedHashMap<Method, MethodHandler>();
List<DefaultMethodHandler> defaultMethodHandlers = new LinkedList<DefaultMethodHandler>();
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 {
methodToHandler.put(method, nameToHandler.get(Feign.configKey(target.type(), method)));
}
}
InvocationHandler handler = factory.create(target, methodToHandler);
T proxy = (T) Proxy.newProxyInstance(target.type().getClassLoader(),
new Class<?>[] {target.type()}, handler);
for (DefaultMethodHandler defaultMethodHandler : defaultMethodHandlers) {
defaultMethodHandler.bindTo(proxy);
}
return proxy;
}
// SpringMvcContract的父类BaseContract
@Override
public List<MethodMetadata> parseAndValidatateMetadata(Class<?> targetType) {
checkState(targetType.getTypeParameters().length == 0, "Parameterized types unsupported: %s",
targetType.getSimpleName());
checkState(targetType.getInterfaces().length <= 1, "Only single inheritance supported: %s",
targetType.getSimpleName());
if (targetType.getInterfaces().length == 1) {
checkState(targetType.getInterfaces()[0].getInterfaces().length == 0,
"Only single-level inheritance supported: %s",
targetType.getSimpleName());
}
Map<String, MethodMetadata> result = new LinkedHashMap<String, MethodMetadata>();
for (Method method : targetType.getMethods()) {
if (method.getDeclaringClass() == Object.class ||
(method.getModifiers() & Modifier.STATIC) != 0 ||
Util.isDefault(method)) {
continue;
}
MethodMetadata metadata = parseAndValidateMetadata(targetType, method);
checkState(!result.containsKey(metadata.configKey()), "Overrides unsupported: %s",
metadata.configKey());
result.put(metadata.configKey(), metadata);
}
return new ArrayList<>(result.values());
}
// ReflectiveFeign内部类ParseHandlersByName
public Map<String, MethodHandler> apply(Target key) {
List<MethodMetadata> metadata = contract.parseAndValidatateMetadata(key.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);
} else if (md.bodyIndex() != null) {
buildTemplate = new BuildEncodedTemplateFromArgs(md, encoder, queryMapEncoder);
} else {
buildTemplate = new BuildTemplateByResolvingArgs(md, queryMapEncoder);
}
result.put(md.configKey(),
factory.create(key, md, buildTemplate, options, decoder, errorDecoder));
}
return result;
}
// SynchronousMethodHandler
public MethodHandler create(Target<?> target,
MethodMetadata md,
RequestTemplate.Factory buildTemplateFromArgs,
Options options,
Decoder decoder,
ErrorDecoder errorDecoder) {
return new SynchronousMethodHandler(target, client, retryer, requestInterceptors, logger,
logLevel, md, buildTemplateFromArgs, options, decoder,
errorDecoder, decode404, closeAfterDecode, propagationPolicy);
}
// InvocationHandlerFactory内部实现类Default
@Override
public InvocationHandler create(Target target, Map<Method, MethodHandler> dispatch) {
return new ReflectiveFeign.FeignInvocationHandler(target, dispatch);
}
}
七、FeignClient调用
服务启动，FeignClient类被收集，对应的代理类被创建。当调用FeignClient类的方法时，实际是对代理类的调用，以完成对静态服务资源的请求
- 方法被调用，代理类FeignInvocationHandler的invoke方法被调用
- dispatch维护了方法与方法处理器的对应关系，获取当前调用的方法对应的方法处理器并执行invoke方法
- 方法处理器的类型为SynchronousMethodHandler
- 在其invoke方法中，根据方法参数和配置的SpringMvc参数转化器，构造RequestTemplate，调用executeAndDecode
- 在方法executeAndDecode中，交由配置的BeanClient来执行请求
- 默认的Client是Client的内部实现类Default，这是Feign的内部类Builder中的默认属性
- 内部实现类Default中，使用JDK原生的HttpURLConnection完成了http请求
// ReflectiveFeign内部类FeignInvocationHandler
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
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();
}
return dispatch.get(method).invoke(args);
}
// SynchronousMethodHandler类
@Override
public Object invoke(Object[] argv) throws Throwable {
RequestTemplate template = buildTemplateFromArgs.create(argv);
Retryer retryer = this.retryer.clone();
while (true) {
try {
return executeAndDecode(template);
} catch (RetryableException e) {
try {
retryer.continueOrPropagate(e);
} catch (RetryableException th) {
Throwable cause = th.getCause();
if (propagationPolicy == UNWRAP && cause != null) {
throw cause;
} else {
throw th;
}
}
if (logLevel != Logger.Level.NONE) {
logger.logRetry(metadata.configKey(), logLevel);
}
continue;
}
}
}
Object executeAndDecode(RequestTemplate template) throws Throwable {
Request request = targetRequest(template);
if (logLevel != Logger.Level.NONE) {
logger.logRequest(metadata.configKey(), logLevel, request);
}
Response response;
long start = System.nanoTime();
try {
response = client.execute(request, options);
} catch (IOException e) {
if (logLevel != Logger.Level.NONE) {
logger.logIOException(metadata.configKey(), logLevel, e, elapsedTime(start));
}
throw errorExecuting(request, e);
}
long elapsedTime = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start);
boolean shouldClose = true;
try {
if (logLevel != Logger.Level.NONE) {
response =
logger.logAndRebufferResponse(metadata.configKey(), logLevel, response, elapsedTime);
}
if (Response.class == metadata.returnType()) {
if (response.body() == null) {
return response;
}
if (response.body().length() == null ||
response.body().length() > MAX_RESPONSE_BUFFER_SIZE) {
shouldClose = false;
return response;
}
// Ensure the response body is disconnected
byte[] bodyData = Util.toByteArray(response.body().asInputStream());
return response.toBuilder().body(bodyData).build();
}
if (response.status() >= 200 && response.status() < 300) {
if (void.class == metadata.returnType()) {
return null;
} else {
Object result = decode(response);
shouldClose = closeAfterDecode;
return result;
}
} else if (decode404 && response.status() == 404 && void.class != metadata.returnType()) {
Object result = decode(response);
shouldClose = closeAfterDecode;
return result;
} else {
throw errorDecoder.decode(metadata.configKey(), response);
}
} catch (IOException e) {
if (logLevel != Logger.Level.NONE) {
logger.logIOException(metadata.configKey(), logLevel, e, elapsedTime);
}
throw errorReading(request, response, e);
} finally {
if (shouldClose) {
ensureClosed(response.body());
}
}
}
// Client内部实现类Default
@Override
public Response execute(Request request, Options options) throws IOException {
HttpURLConnection connection = convertAndSend(request, options);
return convertResponse(connection, request);
}
HttpURLConnection convertAndSend(Request request, Options options) throws IOException {
final HttpURLConnection connection =
(HttpURLConnection) new URL(request.url()).openConnection();
if (connection instanceof HttpsURLConnection) {
HttpsURLConnection sslCon = (HttpsURLConnection) connection;
if (sslContextFactory != null) {
sslCon.setSSLSocketFactory(sslContextFactory);
}
if (hostnameVerifier != null) {
sslCon.setHostnameVerifier(hostnameVerifier);
}
}
connection.setConnectTimeout(options.connectTimeoutMillis());
connection.setReadTimeout(options.readTimeoutMillis());
connection.setAllowUserInteraction(false);
connection.setInstanceFollowRedirects(options.isFollowRedirects());
connection.setRequestMethod(request.httpMethod().name());
Collection<String> contentEncodingValues = request.headers().get(CONTENT_ENCODING);
boolean gzipEncodedRequest =
contentEncodingValues != null && contentEncodingValues.contains(ENCODING_GZIP);
boolean deflateEncodedRequest =
contentEncodingValues != null && contentEncodingValues.contains(ENCODING_DEFLATE);
boolean hasAcceptHeader = false;
Integer contentLength = null;
for (String field : request.headers().keySet()) {
if (field.equalsIgnoreCase("Accept")) {
hasAcceptHeader = true;
}
for (String value : request.headers().get(field)) {
if (field.equals(CONTENT_LENGTH)) {
if (!gzipEncodedRequest && !deflateEncodedRequest) {
contentLength = Integer.valueOf(value);
connection.addRequestProperty(field, value);
}
} else {
connection.addRequestProperty(field, value);
}
}
}
// Some servers choke on the default accept string.
if (!hasAcceptHeader) {
connection.addRequestProperty("Accept", "*/*");
}
if (request.requestBody().asBytes() != null) {
if (contentLength != null) {
connection.setFixedLengthStreamingMode(contentLength);
} else {
connection.setChunkedStreamingMode(8196);
}
connection.setDoOutput(true);
OutputStream out = connection.getOutputStream();
if (gzipEncodedRequest) {
out = new GZIPOutputStream(out);
} else if (deflateEncodedRequest) {
out = new DeflaterOutputStream(out);
}
try {
out.write(request.requestBody().asBytes());
} finally {
try {
out.close();
} catch (IOException suppressed) { // NOPMD
}
}
}
return connection;
}
八、替换Http请求组件
只使用Feign时，默认的Client是内部类Default，可以通过配置依赖选择使用ApacheHttpClient或OkHttpClient
<!-- https://mvnrepository.com/artifact/io.github.openfeign/feign-httpclient -->
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-httpclient</artifactId>
<version>11.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/io.github.openfeign/feign-okhttp -->
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-okhttp</artifactId>
<version>11.0</version>
</dependency>
最后
感谢大家看到这里，文章有不足，欢迎大家指出
