关于Fegin，可以学习下面的文章
pmo引入
如果要跑起来的话，还需要consul 和 loadbalancer(Eureka，Ribbon的替代)
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
<version>3.0.2</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-consul-discovery</artifactId>
<version>3.0.2</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-loadbalancer</artifactId>
<version>3.0.2</version>
</dependency>
spring boot 引入
@SpringBootApplication
@EnableFeignClients
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
@EnableFeignClients
用了@Import({FeignClientsRegistrar.class})
参照spring boot Appollo加载过程
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
@Documented
@Import({FeignClientsRegistrar.class})
public @interface EnableFeignClients {
String[] value() default {};
String[] basePackages() default {};
Class<?>[] basePackageClasses() default {};
Class<?>[] defaultConfiguration() default {};
Class<?>[] clients() default {};
}
FeignClientsRegistrar
实现了3个接口
- ImportBeanDefinitionRegistrar：主要是这个，重写了它的registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionRegistry registry)接口
- ResourceLoaderAware：注入ResourceLoader
- EnvironmentAware：注入Environment
class FeignClientsRegistrar implements ImportBeanDefinitionRegistrar, ResourceLoaderAware, EnvironmentAware {
public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionRegistry registry) {
// 注册默认配置
this.registerDefaultConfiguration(metadata, registry);
// 注册客户端
this.registerFeignClients(metadata, registry);
}
}
注册默认配置
private void registerDefaultConfiguration(AnnotationMetadata metadata, BeanDefinitionRegistry registry) {
Map<String, Object> defaultAttrs = metadata.getAnnotationAttributes(EnableFeignClients.class.getName(), true);
// defaultConfiguration 这个属性一定有，默认空数组
if (defaultAttrs != null && defaultAttrs.containsKey("defaultConfiguration")) {
String name;
// 是否有内部类
if (metadata.hasEnclosingClass()) {
name = "default." + metadata.getEnclosingClassName();
} else {
name = "default." + metadata.getClassName();
}
// 注册默认的配置类，也可以通过配置文件，修改默认配置信息
this.registerClientConfiguration(registry, name, defaultAttrs.get("defaultConfiguration"));
}
}
private void registerClientConfiguration(BeanDefinitionRegistry registry, Object name, Object configuration) {
// 向spring 容器注册一个Bean：FeignClientSpecification
// 构造函数包含两个参数
BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(FeignClientSpecification.class);
builder.addConstructorArgValue(name);
builder.addConstructorArgValue(configuration);
registry.registerBeanDefinition(name + "." + FeignClientSpecification.class.getSimpleName(), builder.getBeanDefinition());
}
FeignClientSpecification
实现了：Specification的getConfiguration方法
Specification 是 NamedContextFactory类的内部接口
具体的流程后面再说，先看下它的定义，很简单
class FeignClientSpecification implements Specification {
private String name;
private Class<?>[] configuration;
FeignClientSpecification() {
}
FeignClientSpecification(String name, Class<?>[] configuration) {
this.name = name;
this.configuration = configuration;
}
。。。
public Class<?>[] getConfiguration() {
return this.configuration;
}
。。。
}
注册客户端
public void registerFeignClients(AnnotationMetadata metadata, BeanDefinitionRegistry registry) {
LinkedHashSet<BeanDefinition> candidateComponents = new LinkedHashSet();
Map<String, Object> attrs = metadata.getAnnotationAttributes(EnableFeignClients.class.getName());
Class<?>[] clients = attrs == null ? null : (Class[])((Class[])attrs.get("clients"));
// 是否通过 @EnableFeignClients 的clients 配置了 客户端类
if (clients != null && clients.length != 0) {
Class[] var12 = clients;
int var14 = clients.length;
for(int var16 = 0; var16 < var14; ++var16) {
Class<?> clazz = var12[var16];
candidateComponents.add(new AnnotatedGenericBeanDefinition(clazz));
}
} else {
// 通过扫描来FeignClient注解找到FeignClients
ClassPathScanningCandidateComponentProvider scanner = this.getScanner();
scanner.setResourceLoader(this.resourceLoader);
scanner.addIncludeFilter(new AnnotationTypeFilter(FeignClient.class));
Set<String> basePackages = this.getBasePackages(metadata);
Iterator var8 = basePackages.iterator();
while(var8.hasNext()) {
String basePackage = (String)var8.next();
// 扫描指定的包
candidateComponents.addAll(scanner.findCandidateComponents(basePackage));
}
}
Iterator var13 = candidateComponents.iterator();
while(var13.hasNext()) {
BeanDefinition candidateComponent = (BeanDefinition)var13.next();
if (candidateComponent instanceof AnnotatedBeanDefinition) {
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 = this.getClientName(attributes);
// 注册配置类， @FeignClient的configuration 属性指定的类
this.registerClientConfiguration(registry, name, attributes.get("configuration"));
// 注册客户端类
this.registerFeignClient(registry, annotationMetadata, attributes);
}
}
}
private void registerFeignClient(BeanDefinitionRegistry registry, AnnotationMetadata annotationMetadata, Map<String, Object> attributes) {
String className = annotationMetadata.getClassName();
Class clazz = ClassUtils.resolveClassName(className, (ClassLoader)null);
ConfigurableBeanFactory beanFactory = registry instanceof ConfigurableBeanFactory ? (ConfigurableBeanFactory)registry : null;
String contextId = this.getContextId(beanFactory, attributes);
String name = this.getName(attributes);
// 这里有个FactoryBean不过这边是主动new的不是，让spring容器管理
FeignClientFactoryBean factoryBean = new FeignClientFactoryBean();
factoryBean.setBeanFactory(beanFactory);
factoryBean.setName(name);
factoryBean.setContextId(contextId);
factoryBean.setType(clazz);
BeanDefinitionBuilder definition = BeanDefinitionBuilder.genericBeanDefinition(clazz, () -> {
factoryBean.setUrl(this.getUrl(beanFactory, attributes));
factoryBean.setPath(this.getPath(beanFactory, attributes));
factoryBean.setDecode404(Boolean.parseBoolean(String.valueOf(attributes.get("decode404"))));
Object fallback = attributes.get("fallback");
// 是否定义了熔断处理类
if (fallback != null) {
factoryBean.setFallback(fallback instanceof Class ? (Class)fallback : ClassUtils.resolveClassName(fallback.toString(), (ClassLoader)null));
}
Object fallbackFactory = attributes.get("fallbackFactory");
if (fallbackFactory != null) {
factoryBean.setFallbackFactory(fallbackFactory instanceof Class ? (Class)fallbackFactory : ClassUtils.resolveClassName(fallbackFactory.toString(), (ClassLoader)null));
}
// 真正的创建 FeginClient
return factoryBean.getObject();
});
// 通过set方法注入
definition.setAutowireMode(2);
// 延迟初始化，用到的时候 才实例化
definition.setLazyInit(true);
this.validate(attributes);
AbstractBeanDefinition beanDefinition = definition.getBeanDefinition();
beanDefinition.setAttribute("factoryBeanObjectType", className);
beanDefinition.setAttribute("feignClientsRegistrarFactoryBean", factoryBean);
boolean primary = (Boolean)attributes.get("primary");
beanDefinition.setPrimary(primary);
String[] qualifiers = this.getQualifiers(attributes);
if (ObjectUtils.isEmpty(qualifiers)) {
qualifiers = new String[]{contextId + "FeignClient"};
}
BeanDefinitionHolder holder = new BeanDefinitionHolder(beanDefinition, className, qualifiers);
// 将客户端Bean定义注册到spring容器
BeanDefinitionReaderUtils.registerBeanDefinition(holder, registry);
}
FeignClientFactoryBean
实现了：
- FactoryBean，这个接口的作用是，当spring创建实现了FactoryBean接口的Bean时，当你将这个类型注入到其他对象时，实际上返回的是getObject方法返回的对象，返回的类型是getObjectType返回的类型
- InitializingBean：spring生命周期接口，构造函数调用完，调用
- ApplicationContextAware：注入ApplicationContext
- BeanFactoryAware：注入BeanFactory
public class FeignClientFactoryBean implements FactoryBean<Object>, InitializingBean, ApplicationContextAware, BeanFactoryAware {
protected <T> T loadBalance(Builder builder, FeignContext context, HardCodedTarget<T> target) {
Client client = (Client)this.getOptional(context, Client.class);
if (client != null) {
builder.client(client);
Targeter targeter = (Targeter)this.get(context, Targeter.class);
return targeter.target(this, builder, context, target);
} else {
throw new IllegalStateException("No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-loadbalancer?");
}
}
public Object getObject() {
return this.getTarget();
}
<T> T getTarget() {
FeignContext context = this.beanFactory != null ? (FeignContext)this.beanFactory.getBean(FeignContext.class) : (FeignContext)this.applicationContext.getBean(FeignContext.class);
Builder builder = this.feign(context);
if (!StringUtils.hasText(this.url)) {
// 不设定url时
if (!this.name.startsWith("http")) {
this.url = "http://" + this.name;
} else {
this.url = this.name;
}
this.url = this.url + this.cleanPath();
return this.loadBalance(builder, context, new HardCodedTarget(this.type, this.name, this.url));
} else {
// 设定url时
if (StringUtils.hasText(this.url) && !this.url.startsWith("http")) {
this.url = "http://" + this.url;
}
String url = this.url + this.cleanPath();
Client client = (Client)this.getOptional(context, Client.class);
if (client != null) {
if (client instanceof FeignBlockingLoadBalancerClient) {
client = ((FeignBlockingLoadBalancerClient)client).getDelegate();
}
if (client instanceof RetryableFeignBlockingLoadBalancerClient) {
client = ((RetryableFeignBlockingLoadBalancerClient)client).getDelegate();
}
builder.client(client);
}
Targeter targeter = (Targeter)this.get(context, Targeter.class);
return targeter.target(this, builder, context, new HardCodedTarget(this.type, this.name, url));
}
}
}
这里有两个问题一个Client，一个Targeter
先看Client
所以无论走 if 还是 else 都是从context里取到Client
然后用builder.client创建
不指定url，用name到注册中心取地址，走负载均衡
指定url的时候走else，直接访问url，不走负载均衡
请注意这句，最终返回的对象，是根据Client造出来的
Client client = (Client)this.getOptional(context, Client.class);
protected <T> T getOptional(FeignContext context, Class<T> type) {
return context.getInstance(this.contextId, type);
}
public <T> T getInstance(String name, Class<T> type) {
AnnotationConfigApplicationContext context = this.getContext(name);
try {
return context.getBean(type);
} catch (NoSuchBeanDefinitionException var5) {
return null;
}
}
可以看到 Client 是从AnnotationConfigApplicationContext 里取出来的
但我们并没有配置或创建这个Bean
所以只有一种可能 通过@Configuration 创建出来的
找一下
spring.factories
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.openfeign.hateoas.FeignHalAutoConfiguration,\
org.springframework.cloud.openfeign.FeignAutoConfiguration,\
org.springframework.cloud.openfeign.encoding.FeignAcceptGzipEncodingAutoConfiguration,\
org.springframework.cloud.openfeign.encoding.FeignContentGzipEncodingAutoConfiguration,\
org.springframework.cloud.openfeign.loadbalancer.FeignLoadBalancerAutoConfiguration
在FeignLoadBalancerAutoConfiguration里发现了
@ConditionalOnClass({Feign.class})
@ConditionalOnBean({LoadBalancerClient.class, LoadBalancerClientFactory.class})
@AutoConfigureBefore({FeignAutoConfiguration.class})
@AutoConfigureAfter({BlockingLoadBalancerClientAutoConfiguration.class, LoadBalancerAutoConfiguration.class})
@EnableConfigurationProperties({FeignHttpClientProperties.class})
@Configuration(
proxyBeanMethods = false
)
@Import({HttpClientFeignLoadBalancerConfiguration.class, OkHttpFeignLoadBalancerConfiguration.class, HttpClient5FeignLoadBalancerConfiguration.class, DefaultFeignLoadBalancerConfiguration.class})
public class FeignLoadBalancerAutoConfiguration {
public FeignLoadBalancerAutoConfiguration() {
}
}
一共引进了4个LoadBalancer
// ApacheHttpClient请求配置
HttpClientFeignLoadBalancerConfiguration.class
// OkHttp请求配置
OkHttpFeignLoadBalancerConfiguration.class
// ApacheHttpClient5请求配置
HttpClient5FeignLoadBalancerConfiguration.class
// 默认Url请求配置
DefaultFeignLoadBalancerConfiguration.class
因为我们没做任何配置所以走DefaultFeignLoadBalancerConfiguration
@Configuration(
proxyBeanMethods = false
)
@EnableConfigurationProperties({LoadBalancerProperties.class})
class DefaultFeignLoadBalancerConfiguration {
DefaultFeignLoadBalancerConfiguration() {
}
@Bean
@ConditionalOnMissingBean
@Conditional({OnRetryNotEnabledCondition.class})
public Client feignClient(LoadBalancerClient loadBalancerClient, LoadBalancerProperties properties, LoadBalancerClientFactory loadBalancerClientFactory) {
return new FeignBlockingLoadBalancerClient(new Default((SSLSocketFactory)null, (HostnameVerifier)null), loadBalancerClient, properties, loadBalancerClientFactory);
}
@Bean
@ConditionalOnMissingBean
@ConditionalOnClass(
name = {"org.springframework.retry.support.RetryTemplate"}
)
@ConditionalOnBean({LoadBalancedRetryFactory.class})
@ConditionalOnProperty(
value = {"spring.cloud.loadbalancer.retry.enabled"},
havingValue = "true",
matchIfMissing = true
)
public Client feignRetryClient(LoadBalancerClient loadBalancerClient, LoadBalancedRetryFactory loadBalancedRetryFactory, LoadBalancerProperties properties, LoadBalancerClientFactory loadBalancerClientFactory) {
return new RetryableFeignBlockingLoadBalancerClient(new Default((SSLSocketFactory)null, (HostnameVerifier)null), loadBalancerClient, loadBalancedRetryFactory, properties, loadBalancerClientFactory);
}
}
spring.cloud.loadbalancer.retry.enabled 这个我们没配
所以Client就是RetryableFeignBlockingLoadBalancerClient
再看Targeter
不罗嗦了，是在FeignAutoConfiguration里配的
这里同时还生产了很多类
其中FeignContext很重要，之后讲
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(Feign.class)
@EnableConfigurationProperties({ FeignClientProperties.class, FeignHttpClientProperties.class,
FeignEncoderProperties.class })
@Import(DefaultGzipDecoderConfiguration.class)
public class FeignAutoConfiguration {
@Bean
public FeignContext feignContext() {
FeignContext context = new FeignContext();
context.setConfigurations(this.configurations);
return context;
}
@Configuration(proxyBeanMethods = false)
@Conditional(FeignCircuitBreakerDisabledConditions.class)
protected static class DefaultFeignTargeterConfiguration {
@Bean
@ConditionalOnMissingBean
public Targeter feignTargeter() {
return new DefaultTargeter();
}
}
}
没有feign.circuitbreaker.enabled或它为false时
返回DefaultTargeter
class DefaultTargeter implements Targeter {
@Override
public <T> T target(FeignClientFactoryBean factory, Feign.Builder feign, FeignContext context,
Target.HardCodedTarget<T> target) {
return feign.target(target);
}
}
然后看Builder 的target了
public static class Builder {
private final List<RequestInterceptor> requestInterceptors = new ArrayList();
private Level logLevel;
private Contract contract;
private Client client;
private Retryer retryer;
private Logger logger;
private Encoder encoder;
private Decoder decoder;
private QueryMapEncoder queryMapEncoder;
private ErrorDecoder errorDecoder;
private Options options;
private InvocationHandlerFactory invocationHandlerFactory;
private boolean decode404;
private boolean closeAfterDecode;
private ExceptionPropagationPolicy propagationPolicy;
private boolean forceDecoding;
private List<Capability> capabilities;
public Builder() {
this.logLevel = Level.NONE;
this.contract = new Default();
this.client = new feign.Client.Default((SSLSocketFactory)null, (HostnameVerifier)null);
this.retryer = new feign.Retryer.Default();
this.logger = new NoOpLogger();
this.encoder = new feign.codec.Encoder.Default();
this.decoder = new feign.codec.Decoder.Default();
this.queryMapEncoder = new FieldQueryMapEncoder();
this.errorDecoder = new feign.codec.ErrorDecoder.Default();
this.options = new Options();
this.invocationHandlerFactory = new feign.InvocationHandlerFactory.Default();
this.closeAfterDecode = true;
this.propagationPolicy = ExceptionPropagationPolicy.NONE;
this.forceDecoding = false;
this.capabilities = new ArrayList();
}
。。。
public <T> T target(Target<T> target) {
return build().newInstance(target);
}
public Feign build() {
Client client = (Client)Capability.enrich(this.client, this.capabilities);
Retryer retryer = (Retryer)Capability.enrich(this.retryer, this.capabilities);
List<RequestInterceptor> requestInterceptors = (List)this.requestInterceptors.stream().map((ri) -> {
return (RequestInterceptor)Capability.enrich(ri, this.capabilities);
}).collect(Collectors.toList());
Logger logger = (Logger)Capability.enrich(this.logger, this.capabilities);
Contract contract = (Contract)Capability.enrich(this.contract, this.capabilities);
Options options = (Options)Capability.enrich(this.options, this.capabilities);
Encoder encoder = (Encoder)Capability.enrich(this.encoder, this.capabilities);
Decoder decoder = (Decoder)Capability.enrich(this.decoder, this.capabilities);
InvocationHandlerFactory invocationHandlerFactory = (InvocationHandlerFactory)Capability.enrich(this.invocationHandlerFactory, this.capabilities);
QueryMapEncoder queryMapEncoder = (QueryMapEncoder)Capability.enrich(this.queryMapEncoder, this.capabilities);
Factory synchronousMethodHandlerFactory = new Factory(client, retryer, requestInterceptors, logger, this.logLevel, this.decode404, this.closeAfterDecode, this.propagationPolicy, this.forceDecoding);
ParseHandlersByName handlersByName = new ParseHandlersByName(contract, options, encoder, decoder, queryMapEncoder, this.errorDecoder, synchronousMethodHandlerFactory);
return new ReflectiveFeign(handlersByName, invocationHandlerFactory, queryMapEncoder);
}
}
来了
ReflectiveFeign.newInstance
返回代理类
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.
*/
@SuppressWarnings("unchecked")
@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;
}
}
到此为止， Open Feign 的加载过程讲完了
但 还不够详细下面在补充点
FeignContext
之前提到了FeignContext
任何一段程序都是运行在一个上下文环境中的
所以看看它做了些什么
public class FeignAutoConfiguration {
@Autowired(required = false)
private List<FeignClientSpecification> configurations = new ArrayList<>();
@Bean
public FeignContext feignContext() {
FeignContext context = new FeignContext();
context.setConfigurations(this.configurations);
return context;
}
}
FeignContext是在FeignAutoConfiguration 里生产出来的
并传入了configurations：所有由@FeignClient注解的类
FeignContext
继承自：NamedContextFactory
构造函数里，给父类构造函数传了个FeignClientsConfiguration.class
真正的配置都在FeignClientsConfiguration里
public class FeignContext extends NamedContextFactory<FeignClientSpecification> {
public FeignContext() {
super(FeignClientsConfiguration.class, "feign", "feign.client.name");
}
// 下面两个函数 取得Bean用的
@Nullable
public <T> T getInstanceWithoutAncestors(String name, Class<T> type) {。。。}
@Nullable
public <T> Map<String, T> getInstancesWithoutAncestors(String name, Class<T> type) {。。。 }
}
NamedContextFactory
构造函数并没有做什么
大家可以向上找，找到Client 的创建过程
里面的函数getContext
其中用到了
createContext：初始化 每个@FeignClient 的context
public abstract class NamedContextFactory<C extends NamedContextFactory.Specification>
implements DisposableBean, ApplicationContextAware {
public NamedContextFactory(Class<?> defaultConfigType, String propertySourceName, String propertyName) {
this.defaultConfigType = defaultConfigType;
this.propertySourceName = propertySourceName;
this.propertyName = propertyName;
}
protected AnnotationConfigApplicationContext createContext(String name) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
// 这块是 取得 @EnableFeignClients @FeignClient 注解里的configuration 并将他们注册到对应的 context里
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;
}
}
这句话注册了FeignClientsConfiguration
也就是说它会被spring容器管理并加载
context.register(PropertyPlaceholderAutoConfiguration.class, this.defaultConfigType);
好看看它都做了什么
FeignClientsConfiguration
@Configuration(proxyBeanMethods = false)
public class FeignClientsConfiguration {
。。。
@Bean
@ConditionalOnMissingBean
public Decoder feignDecoder() {。。。 }
@Bean
@ConditionalOnMissingBean
@ConditionalOnMissingClass("org.springframework.data.domain.Pageable")
public Encoder feignEncoder(ObjectProvider<AbstractFormWriter> formWriterProvider) {
。。。
}
@Bean
@ConditionalOnClass(name = "org.springframework.data.domain.Pageable")
@ConditionalOnMissingBean
public Encoder feignEncoderPageable(ObjectProvider<AbstractFormWriter> formWriterProvider) {
。。。
}
@Bean
@ConditionalOnClass(name = "org.springframework.data.domain.Pageable")
@ConditionalOnMissingBean
public QueryMapEncoder feignQueryMapEncoderPageable() {
。。。
}
@Bean
@ConditionalOnMissingBean
public Contract feignContract(ConversionService feignConversionService) {
boolean decodeSlash = feignClientProperties == null || feignClientProperties.isDecodeSlash();
return new SpringMvcContract(this.parameterProcessors, feignConversionService, decodeSlash);
}
@Bean
public FormattingConversionService feignConversionService() {
FormattingConversionService conversionService = new DefaultFormattingConversionService();
for (FeignFormatterRegistrar feignFormatterRegistrar : this.feignFormatterRegistrars) {
feignFormatterRegistrar.registerFormatters(conversionService);
}
return conversionService;
}
。。。
}
encode,decode什么的不说了
主要是feignContract方法
创建了SpringMvcContract
Feign本身是由一套自己的注解的，但用了OpenFeign就可以直接使用springmvc的注解了
就是由这个类完成了转换
SpringMvcContract
继承自：Contract.BaseContract
实现了：ResourceLoaderAware
具体的实现我就不讲了，看下我列出来的两个方法
public class SpringMvcContract extends Contract.BaseContract implements ResourceLoaderAware {
public SpringMvcContract(List<AnnotatedParameterProcessor> annotatedParameterProcessors,
ConversionService conversionService, boolean decodeSlash) {
Assert.notNull(annotatedParameterProcessors, "Parameter processors can not be null.");
Assert.notNull(conversionService, "ConversionService can not be null.");
List<AnnotatedParameterProcessor> processors = getDefaultAnnotatedArgumentsProcessors();
processors.addAll(annotatedParameterProcessors);
annotatedArgumentProcessors = toAnnotatedArgumentProcessorMap(processors);
this.conversionService = conversionService;
convertingExpanderFactory = new ConvertingExpanderFactory(conversionService);
this.decodeSlash = decodeSlash;
}
private List<AnnotatedParameterProcessor> getDefaultAnnotatedArgumentsProcessors() {
List<AnnotatedParameterProcessor> annotatedArgumentResolvers = new ArrayList<>();
// 这些注解的名字大家都应该熟悉吧
annotatedArgumentResolvers.add(new MatrixVariableParameterProcessor());
annotatedArgumentResolvers.add(new PathVariableParameterProcessor());
annotatedArgumentResolvers.add(new RequestParamParameterProcessor());
annotatedArgumentResolvers.add(new RequestHeaderParameterProcessor());
annotatedArgumentResolvers.add(new QueryMapParameterProcessor());
annotatedArgumentResolvers.add(new RequestPartParameterProcessor());
return annotatedArgumentResolvers;
}
。。。
}
open feign 从3.0开始就不支持Ribbon
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