RestTemplate 拦截器

Question

我目前正在尝试合并HandlerInterceptorAdapter，但它没有被注册，并且将其与其他答案进行比较很困难，因为每个人都在使用不同的东西。而且我知道 WebMvcConfigureAdapter 已被弃用，某些版本控制超出了我对项目范围的控制范围，请参阅下面的使用规范。

有人可以提供一些关于将拦截器与 RestTemplate（不是 ClientHttpRequestInterceptor）结合的指导。

主要：

@SpringBootApplication
@EnableRetry
public class Application extends SpringBootServletInitializer {

  public static void main(String[] args) {

   ApplicationContext ctx = SpringApplication.run(Application.class, args);

  }


  @Override
  protected SpringApplicationBuilder configure(SpringApplicationBuilder applicationBuilder) {

    return applicationBuilder.sources(Application.class);

  }

  @Bean
  private RestTemplate restTemplate(){
    Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("redacted", 8080));

    SimpleClientHttpRequestFactory simpleClientHttpRequestFactory = new SimpleClientHttpRequestFactory();
    simpleClientHttpRequestFactory.setProxy(proxy);
    simpleClientHttpRequestFactory.setOutputStreaming(false);

    RestTemplate template = new RestTemplate();
    template.setErrorHandler(new MyResponseErrorHandler());

    return template;
  }
}

拦截器：com.example.foo.config.request.interceptor

@Component
public class MyInterceptor extends HandlerInterceptorAdapter {

  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    System.out.println("INTERCEPTED");
    return super.preHandle(request, response, handler);
  }
}

InterceptorConfig : com.example.foo.config.request.interceptor

@Configuration
public class InterceptorConfig extends WebMvcConfigurerAdapter  {

  @Bean
  MyInterceptor myInterceptor() {
    return new MyInterceptor();
  }

  @Override
  public void addInterceptors(InterceptorRegistry registry) {
    super.addInterceptors(registry);
    System.out.println("Adding interceptor");
    registry.addInterceptor(myInterceptor());
  }

}

“添加拦截器”确实被记录下来，所以我知道正在扫描配置。我只是无法记录任何拦截器逻辑。

使用：

• Spring Boot v1.5.15
• 春季版：4.3.18.RELEASE

Answer 1

HandlerInterceptorAdapter是供服务器端（即RestController）在服务器处理HTTP请求时拦截一些重要事件的，与使用什么HTTP客户端（如RestTemplate）无关。

如果您想使用RestTemplate 作为HTTP 客户端，并且想在请求发出之前拦截请求并在收到响应之后拦截，则必须使用ClientHttpRequestInterceptor。

我正在尝试以更灵活的方式拦截请求和响应 比 ClientHttpRequestInterceptor。

根据您上面的评论，您无法处理的实际用例是什么？我认为ClientHttpRequestInterceptor 已经足够灵活，可以实现任何复杂的逻辑来拦截请求和响应。由于您的问题没有提供任何有关您需要如何拦截的信息，我只能举一个一般性的例子来说明ClientHttpRequestInterceptor 可以提供什么。

将 RestTemplate 配置为使用拦截器：

RestTemplate rt = new RestTemplate();
List<ClientHttpRequestInterceptor> interceptors= new ArrayList<ClientHttpRequestInterceptor>();
inteceptors.add(new MyClientHttpRequestInterceptor());

ClientHttpRequestInterceptor 看起来像：

public class MyClientHttpRequestInterceptor implements ClientHttpRequestInterceptor{

    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution)
            throws IOException {

        //The HTTP request and its body are intercepted here which you can log them or modify them. e.g.
        System.out.println("Log the HTTP request header: " + request.getHeaders());

        //Modify the HTTP request header....
        request.getHeaders().add("foo", "fooValue");

        //Throw exception if you do not want to send the HTTP request

        //If it is at the end of the interceptor chain , call execution.execute() to confirm sending the HTTP request will return the response in ClientHttpResponse
        //Otherwise, it will pass the request to the next interceptor in the chain to process
        ClientHttpResponse response= execution.execute(request, body);

        //The HTTP response is intercepted here which you can log them or modify them.e.g.
        System.out.println("Log the HTTP response header: " + response.getHeaders());

        //Modify the HTTP response header
        response.getHeaders().add("bar", "barValue");

        return response;
    }
}

请注意，您还可以配置ClientHttpRequestInterceptor 链，允许将一些复杂的请求和响应拦截逻辑拆分为许多小块和可重复使用的ClientHttpRequestInterceptor。它采用Chain of responsibility 设计模式设计，其API 体验与Servlet 中的Filter#doFilter() 非常相似。

Answer 2

正如@WonChulHeo 所说，您不能将HandlerInterceptorAdapter 与RestTemplate 一起使用。只有ClientHttpRequestInterceptor。目前尚不清楚您为什么确切需要HandlerInterceptorAdapter - 我们只能看到您正在尝试记录请求拦截的事实。 ClientHttpRequestInterceptor 绝对能够做到这一点，甚至更多——请查看下面的工作示例。

附：您的代码中有错误 - 您不能使用 private 访问 @Bean 方法 - 请检查您的 private RestTemplate restTemplate() {...

@Slf4j
@RestController
@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        new SpringApplicationBuilder(Application.class)
                .bannerMode(Banner.Mode.OFF)
                .run(args);
    }

    @GetMapping("/users/{id}")
    public User get(@PathVariable int id) {
        log.info("[i] Controller: received request GET /users/{}", id);
        return new User(id, "John Smith");
    }

    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder templateBuilder) {
        ClientHttpRequestFactory requestFactory = new BufferingClientHttpRequestFactory(new SimpleClientHttpRequestFactory());
        return templateBuilder
                .interceptors((request, bytes, execution) -> {
                    URI uri = request.getURI();
                    HttpMethod method = request.getMethod();

                    log.info("[i] Interceptor: requested {} {}", method, uri);
                    log.info("[i] Interceptor: request headers {}", request.getHeaders());

                    ClientHttpRequest delegate = requestFactory.createRequest(uri, method);
                    request.getHeaders().forEach((header, values) -> delegate.getHeaders().put(header, values));

                    ClientHttpResponse response = delegate.execute();
                    log.info("[i] Interceptor: response status: {}", response.getStatusCode().name());
                    log.info("[i] Interceptor: response headers: {}", response.getHeaders());
                    String body = StreamUtils.copyToString(response.getBody(), Charset.defaultCharset());
                    log.info("[i] Interceptor: response body: '{}'", body);

                    return response;
                })
                .rootUri("http://localhost:8080")
                .build();
    }

    @Bean
    ApplicationRunner run(RestTemplate restTemplate) {
        return args -> {
            ResponseEntity<User> response = restTemplate.getForEntity("/users/{id}", User.class, 1);
            if (response.getStatusCode().is2xxSuccessful()) {
                log.info("[i] User: {}", response.getBody());
            } else {
                log.error("[!] Error: {}", response.getStatusCode());
            }
        };
    }
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private int id;
    private String name;
}

Answer 3

RestTemplate 期望 ClientHttpRequestInterceptor

setInterceptors(List<ClientHttpRequestInterceptor> interceptors)

设置此访问器应使用的请求拦截器。

您可以使用Servlet Filter 来“拦截”请求/响应，

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
        throws IOException, ServletException {
    HttpServletRequest httpRequest = (HttpServletRequest) request;
    HttpServletResponse httpResponse = (HttpServletResponse) response;

使用 servlet 过滤器来实现这一点。这里根本不涉及 Spring

但是您必须将 RestTemplate 更改为使用其他框架作为 jersey

Jersey 提供了一个非常方便的实现，例如称为 LoggingFilter 的过滤器，它可以帮助记录各种传入和传出流量。

Answer 4

HandlerInterceptorAdapter 是适用于@Controller 或@RestController 的实现。不是RestTemplete 的实现。

要将其应用于RestTemplete，您需要使用ClientHttpRequestInterceptor。

例如

@Component
public class CustomInterceptor implements ClientHttpRequestInterceptor {
    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
        // ... 
    }
}

@Configuation
public class RestTempleteConfig {

    // ...
    @Autowired
    private CustomInterceptor customInterceptor;

    @Bean
    public RestTemplate restTemplate(){
        RestTemplate template = new RestTemplate();
        List<ClientHttpRequestInterceptor> interceptors = new ArrayList<>();
        template.add(customInterceptor);
        return template;
    }
}