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Feign report 400 processing

2022-04-23 16:49:00 【InfoQ】

There is an interface like this

getXxByIds(String Ids)

id use ',' Separate , After running for a period of time, I reported 400.

Wrong content

feign.FeignException$BadRequest: [400] during [POST] to [http...

Problem recurrence

To simulate the problem

Service interface

@Slf4j
@RestController
public class SkyController {

 @GetMapping(&quot;/sky&quot;)
 public String sky (@RequestParam(required = false) String name) {
 log.info(name);
 return name;
 }

 @PostMapping(&quot;/deliver&quot;)
 public String deliver (String packageBox) {
 log.info(packageBox);
 return packageBox;
 }


 @PostMapping(&quot;/feignPost&quot;)
 public String feignPost(@RequestParam(name = &quot;name&quot;) String name){
 log.info(name);
 return name;
 }


 @PostMapping(&quot;/feignBody&quot;)
 public String feignBody(@RequestBody String name){
 log.info(name);
 return name;
 }


}

Build another service establish feignClinet, The sample service joins the gateway , Service name used , You can use it directly url

//  gateway   The service name 
@FeignClient(value = &quot;paw-dogs-sky-service&quot;)
public interface SkyFeignClient {

 @PostMapping(&quot;/deliver&quot;)
 String deliver (@RequestParam(name = &quot;packageBox&quot;) String packageBox);

 @PostMapping(&quot;/feignPost&quot;)
 String feignPost(@RequestParam(name = &quot;name&quot;) String name);

 @PostMapping(&quot;/feignBody&quot;)
 String feignBody(@RequestBody String name);
}

Writing test classes

@Slf4j
@SpringBootTest
class SkyFeignClientTest {


 @Autowired
 SkyFeignClient skyFeignClient;

 @Test
 void deliver () {
 String param = RandomUtil.randomString(10*1024);
 log.info(param);
 String result = skyFeignClient.deliver(param);
 log.info(result);

 }

 @Test
 void feignPost () {
 String param = RandomUtil.randomString(10*1024);
 log.info(param);
 String result = skyFeignClient.feignPost(param);
 log.info(result);
 }

 @Test
 void feignBody () {
 String param = RandomUtil.randomString(1*1024);
 log.info(param);
 String result = skyFeignClient.feignBody(param);
 log.info(result);
 }
}

Running tests found param large get、post form-url request was aborted ,requestBody Mode request succeeded .

function post form-url request Will find post The request is also sent url Splicing method

use postman Direct access to service testing

Through the length of splicing url The visit to fail

adopt form-url Mode access succeeded

The problem is url The length limit of

url Length limit

browser url Length limit

Server length limit Such as tomcat Limit , nginx url Limit

SpringBoot Project length limit
max-http-header-size
Default 8k, Change the service provided sky Configuration of 100*1024 (100k) , Retry the normal service call .

DataSize maxHttpHeaderSize = DataSize.ofKilobytes(8)

 server:
 port: 8080
 max-http-header-size: 102400

Source code analysis

From exception class SynchronousMethodHandler Starting with debug track

Build the requested class

RequestTemplate

Corresponding query request Use an ordered linked list to store parameters

Map<String, QueryTemplate> queries = new LinkedHashMap<>()

Form like key-->value

packageBox--> packageBox={packageBox}

SpringMvcContract

Handle annotations

Annotations on the class

processAnnotationOnClass

Comments on methods

processAnnotationOnMethod

Comments on parameters

processAnnotationsOnParameter

AnnotatedParameterProcessor

Implementation class of

RequestParamParameterProcessor

Yes query Parameters are encapsulated

public boolean processArgument(AnnotatedParameterContext context,
 Annotation annotation, Method method) {
 int parameterIndex = context.getParameterIndex();
 Class<?> parameterType = method.getParameterTypes()[parameterIndex];
 MethodMetadata data = context.getMethodMetadata();

 if (Map.class.isAssignableFrom(parameterType)) {
 checkState(data.queryMapIndex() == null,
 &quot;Query map can only be present once.&quot;);
 data.queryMapIndex(parameterIndex);

 return true;
 }

 RequestParam requestParam = ANNOTATION.cast(annotation);
 String name = requestParam.value();
 checkState(emptyToNull(name) != null,
 &quot;RequestParam.value() was empty on parameter %s&quot;, parameterIndex);
 context.setParameterName(name);

 //  Encapsulate parameters 
 Collection<String> query = context.setTemplateParameter(name,
 data.template().queries().get(name));
 data.template().query(name, query);
 return true;
 }

SynchronousMethodHandler

invoke Method

executeAndDecode(template, options)

perform http Request and decode .

Object executeAndDecode(RequestTemplate template, Options options) throws Throwable {
 //  Build request 
 Request request = targetRequest(template);

 if (logLevel != Logger.Level.NONE) {
 logger.logRequest(metadata.configKey(), logLevel, request);
 }

 Response response;
 long start = System.nanoTime();
 try {
 //  perform http request 
 response = client.execute(request, options);
 ...
 }

structure Request request , adopt client visit http service . Realized client Yes

Default

LoadBalancerFeignClient

FeignBlockingLoadBalancerClient

solve

1.  Increase the of service providers header Parameters ( More micro services   Not very suitable ) 
2.  Change it to requestBody Call the service

summary

feign By parsing the interface class 、 Method 、 Comments on parameters , adopt

RequestTemplate

@RequestParam With Url Splicing method , To build the

Request

request , adopt Client visit http service . For longer parameters, change to RequestBody Method to call the service .

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https://yzsam.com/2022/04/202204231645272078.html