關於FeignClient使用大全

摘要： 一個最簡單的使用FeignClient的例子如下： 1，新增maven依賴 <dependency> <groupId>org.springframework.cloud</groupId> <ar...

一個最簡單的使用FeignClient的例子如下：

1，新增maven依賴

<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
<version>2.0.2.RELEASE</version>
</dependency>
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-core</artifactId>
<version>9.7.0</version>
</dependency>
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-slf4j</artifactId>
<version>9.7.0</version>
</dependency>

2，編寫FeignClient程式碼

@FeignClient(name = "myFeignClient", url = "http://127.0.0.1:8001")
public interface MyFeignClient {
@RequestMapping(method = RequestMethod.GET, value = "/participate")
String getCategorys(@RequestParam Map<String, Object> params);
}

3，直接使用FeignClient

@Autowired
MyFeignClient myFeignClient;

到此，FeignClient便可正常使用一般的Http介面了~

4，如果想使用檔案上傳介面或者post的x-www-form-urlencoded介面，那需要做如下配置

新增依賴包

<dependency>
<groupId>io.github.openfeign.form</groupId>
<artifactId>feign-form</artifactId>
<version>3.4.1</version>
</dependency>
<dependency>
<groupId>io.github.openfeign.form</groupId>
<artifactId>feign-form-spring</artifactId>
<version>3.4.1</version>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.3</version>
</dependency>

新增bean註解配置

@Bean
@Primary
@Scope("prototype")
public Encoder multipartFormEncoder(ObjectFactory<HttpMessageConverters> messageConverters) {
return new SpringFormEncoder(new SpringEncoder(messageConverters));
}

定義檔案上傳介面

@RequestMapping(value = {"/demo/v1/upload"}, 
method = {RequestMethod.POST}, 
consumes = {MediaType.MULTIPART_FORM_DATA_VALUE})
ReturnResult<ImageVO> uploadFile(
@RequestPart(value = "file") MultipartFile file, 
@RequestParam(value = "bucketName", required = false) String bucketName);

5，如果想使用Apache的httpclient的連線池，可以做如下配置

新增依賴

<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.6</version>
</dependency>
<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-httpclient</artifactId>
<version>9.7.0</version>
</dependency>

新增屬性配置

feign:
okhttp: 
enabled: false
httpclient:
enabled: true
maxConnections: 20480
maxConnectionsPerRoute: 512
timeToLive: 60
connectionTimeout: 10000
userAgent: 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:37.0) Gecko/20100101 Firefox/37.0'

引入FeignAutoConfiguration配置

@Import(FeignAutoConfiguration.class)
@Configuration
public class FeignConfig {
...
}

經過這幾步操作後，便可啟用Apache的httpclient替換其內嵌httpclient。

6，如果想啟用hystrix熔斷降級，則可作如下配置

新增依賴

<dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-hystrix</artifactId>
<version>9.7.0</version>
</dependency>

新增屬性配置

feign:
hystrix: 
enabled: true

hystrix:
command:
default:
execution:
isolation:
thread:
timeoutInMilliseconds: 15000
threadpool:
default:
coreSize: 40
maximumSize: 100
maxQueueSize: 100

新增降級策略

public class MyFeignClientFallback implements MyFeignClient {
@Override
public ReturnResult<ImageVO> uploadFile(MultipartFile file, String bucketName) {
return new ReturnResult<>(5001);
}
}

新增bean配置

@Bean
@Scope("prototype")
public Feign.Builder feignBuilder() {
return HystrixFeign.builder();
}

@Bean
public MyFeignClientFallback fb() {
return new MyFeignClientFallback();
}

更新@FeignClient程式碼

@FeignClient(
name = "myFeignClient", 
url = "http://127.0.0.1:8001",
fallback = MyFeignClientFallback.class,
configuration = {FeignConfig.class})

7，如果想處理熔斷的具體原因，可以做如下更新

更新熔斷策略程式碼實現FallbackFactory介面

public class MyFeignClientFallback implements FallbackFactory<MyFeignClient> {
@Override
public MyFeignClient create(final Throwable cause) {
return new MyFeignClient() {
@Override
public ReturnResult<ImageVO> uploadFile(MultipartFile file, String bucketName) {
// 處理cause

return new ReturnResult<>(5001);
}
};
}
}

更新bean配置

@Bean
public MyFeignClientFallback fbf() {
return new MyFeignClientFallback();
}

更新@FeignClient程式碼

@FeignClient(
name = "myFeignClient", 
url = "http://127.0.0.1:8001",
fallbackFactory = MyFeignClientFallback.class,
configuration = {FeignConfig.class})

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