Spring RestTemplate错误处理

背景

在实际开发中使用RestTemplate 经常会出现返回非200状态码报异常,这是源于RestTemplate 默认响应状态码处理机制,默认情况下RestTemplate如果发生HTTP错误将会抛出以下异常:

1. HttpClientErrorException – in case of HTTP status 4xx
2. HttpServerErrorException – in case of HTTP status 5xx
3. UnknownHttpStatusCodeException – in case of an unknown HTTP status

这个异常都是拓展自RestClientResponseException,但是很明显不能够满足我们的实际业务需求,今天，我们将讨论如何在RestTemplate实例中实现和注入ResponseErrorHandler接口,优雅地处理远程API返回的HTTP错误。

实现ResponseErrorHandler

1. 通过ResponseErrorHandler获取HTTP返回状态,根据我们的实际业务来自定义处理逻辑

2. 实现自定义RestTemplateResponseErrorHandler

   @Component
   public class RestTemplateResponseErrorHandler implements ResponseErrorHandler {
   
       @Override
       public boolean hasError(ClientHttpResponse httpResponse)throws IOException {
           return (httpResponse.getStatusCode().series() == HttpStatus.Series.CLIENT_ERROR
                   || httpResponse.getStatusCode().series() == HttpStatus.Series.SERVER_ERROR);
       }
   
       @Override
       public void handleError(ClientHttpResponse httpResponse)throws IOException {
           if (httpResponse.getStatusCode().series() == HttpStatus.Series.SERVER_ERROR) {
               throw new HttpClientErrorException(httpResponse.getStatusCode());
           } else if (httpResponse.getStatusCode().series() == HttpStatus.Series.CLIENT_ERROR) {
               if (httpResponse.getStatusCode() == HttpStatus.NOT_FOUND) {
                   throw new NotFoundException();
               }
           }
       }
   }
   

3. 将ResponseErrorHandler实现注入到RestTemplate实例中

   @Configuration
   public class RestTemplateConfig {
   
       @Bean
       public RestTemplate restTemplate(ClientHttpRequestFactory factory,RestTemplateResponseErrorHandler restTemplateResponseErrorHandler) throws Exception {
           RestTemplate restTemplate = new RestTemplate(factory);
           restTemplate.setErrorHandler(restTemplateResponseErrorHandler);
           return restTemplate;
       }
   
       @Bean
       public ClientHttpRequestFactory simpleClientHttpRequestFactory() {
           SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
           //读取超时时间设置
           factory.setReadTimeout(5000);
           //连接超时时间设置
           factory.setConnectTimeout(15000);
           return factory;
       }
   }
   

测试

1. 加入依赖

   <!--spring boot test-->
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-test</artifactId>
       <scope>test</scope>
   </dependency>
   

2. 编写测试类

   @RunWith(SpringRunner.class)
   @ContextConfiguration(classes = {NotFoundException.class, UserEntity.class})
   @RestClientTest
   @Slf4j
   public class RestTemplateResponseErrorHandlerIntegrationTest {
   
       @Autowired
       private MockRestServiceServer server;
   
       @Autowired
       private RestTemplateBuilder builder;
   
       @Test(expected = NotFoundException.class)
       public void givenRemoteApiCall_when404Error_thenThrowNotFound() {
           Assert.assertNotNull(this.builder);
           Assert.assertNotNull(this.server);
   
           RestTemplate restTemplate = this.builder
                   .errorHandler(new RestTemplateResponseErrorHandler())
                   .build();
   
           this.server
                   .expect(ExpectedCount.once(), requestTo("/user/load/1000"))
                   .andExpect(method(HttpMethod.GET))
                   .andRespond(withStatus(HttpStatus.NOT_FOUND));
   
           restTemplate.getForObject("/user/load/1000", UserEntity.class);
           this.server.verify();
       }
   }
   

3. 结果

   2020-03-30 14:15:27.503  INFO [aop-spel,,,] 8784 --- [           main] plateResponseErrorHandlerIntegrationTest : No active profile set, falling back to default profiles: default
   2020-03-30 14:15:28.233  INFO [aop-spel,,,] 8784 --- [           main] plateResponseErrorHandlerIntegrationTest : Started RestTemplateResponseErrorHandlerIntegrationTest in 4.541 seconds (JVM running for 8.036)