問(wèn)題

在使用SpringCloud時(shí)，發(fā)現(xiàn)Feign不能發(fā)送POST表單請(qǐng)求

注意：在SpringBoot/Cloud環(huán)境中，使用的FeignClient，在不做額外設(shè)置的情況下，只能使用MVC的注解，也就是@RequestMapping和@RequestBody或者@RequestParam。

FeignClient 的 接口嘗試以 POST表單發(fā)送請(qǐng)求的寫法：

@RequestMapping(value="/someThing/someMethod", method=RequestMethod.POST)
ApiResponse someThing(@RequestParam("name") String value);

在沒(méi)有改變默認(rèn)Encoder的設(shè)置的情況下，F(xiàn)eignClient 對(duì)于簡(jiǎn)單類型的參數(shù)，例如String，Integer這些 wrapped primitive types，這種類型將被編碼為form表單參數(shù)，即便寫了method=RequestMethod.POST，但是參數(shù)沒(méi)有出現(xiàn)在Body中，而是在URL上，不符合需求。

解決方案

<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form</artifactId>
    <version>3.3.0</version>
</dependency>
<dependency>
    <groupId>io.github.openfeign.form</groupId>
    <artifactId>feign-form-spring</artifactId>
    <version>3.3.0</version>
</dependency>

對(duì)應(yīng)FeignClient客戶端

@FeignClient(name="remoteService",configuration = IRemoteService.FormSupportConfig.class)
public interface IRemoteService {
@RequestMapping(value="/someThing/someMethod", 
                                method=RequestMethod.POST, 
                                consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE)
ApiResponse someThing(@RequestBody Map<String, ?> formParams);
}

    class FormSupportConfig {

            @Bean
            public Encoder feignFormEncoder() {
                 return new SpringFormEncoder();
            }
     }
}

這樣就可以發(fā)送表單請(qǐng)求了。

另一種不需要引入依賴的方法

List<NameValuePair> nvps = new ArrayList<>();
nvps.add(new BasicNameValuePair("key1", key1.toString()));
nvps.add(new BasicNameValuePair("key2", StringUtils.join(key2, ",")));
nvps.add(new BasicNameValuePair("key3", key3.toString()));
String queryStr = URLEncodedUtils.format(nvps, Consts.UTF_8);

someThing(queryStr);

對(duì)應(yīng)

@RequestMapping(value="/someThing/someMethod", 
                                method=RequestMethod.POST, 
                                consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE)
ApiResponse someThing(@RequestBody String formParam);

推翻重來(lái)，上面的解決方案有問(wèn)題

在同時(shí)使用表單和 RequestBody 的時(shí)候，使用上面的配置會(huì)拋異常，

is not a type supported by this encoder

將上面的configuration 改成這個(gè)類就沒(méi)有問(wèn)題了

import feign.codec.Encoder;
import feign.form.FormEncoder;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
import org.springframework.cloud.netflix.feign.support.SpringEncoder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Primary;
import org.springframework.context.annotation.Scope;

import static org.springframework.beans.factory.config.BeanDefinition.SCOPE_PROTOTYPE;

public class CoreFeignConfiguration {

    @Autowired
    private ObjectFactory<HttpMessageConverters> messageConverters;

    @Bean
    @Primary
    @Scope(SCOPE_PROTOTYPE)
    Encoder feignFormEncoder() {
        return new FormEncoder(new SpringEncoder(this.messageConverters));
    }
}