功能

1. 某個rest介面是公開的，它的feign服務的介面需要授權
2. 重寫一個HttpServletRequestWrapper，實作模擬登錄之后把header頭進行填充
3. 介面請求背景關系里的token，通過Feign攔截器轉給每個feign請求背景關系
4. 完成對feign介面的自動授權訪問　

重寫HttpServletRequestWrapper

/**
 * 自定義的請求背景關系.
 */
public class CustomHttpServletRequest extends HttpServletRequestWrapper {

    private Map<String, String> headers = new HashMap<>();

    public CustomHttpServletRequest(HttpServletRequest request) {
        super(request);
    }

    public void addHeader(String name, String value) {
        headers.put(name, value);
    }

    @Override
    public String getHeader(String name) {
        String value = https://www.cnblogs.com/lori/p/super.getHeader(name);

        if (headers.containsKey(name)) {
            value = headers.get(name);
        }

        return value;
    }

    @Override
    public Enumeration getHeaderNames() {
        List names = Collections.list(super.getHeaderNames());
        names.addAll(headers.keySet());

        return Collections.enumeration(names);
    }

    @Override
    public Enumeration getHeaders(String name) {
        List list = Collections.list(super.getHeaders(name));

        if (headers.containsKey(name)) {
            list.add(headers.get(name));
        }

        return Collections.enumeration(list);
    }
}

建立過濾器

@Component
public class CustomFilter implements Filter {
    @Autowired
    KcUserClient kcUserClient;

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        CustomHttpServletRequest request = new CustomHttpServletRequest((HttpServletRequest) servletRequest);
        request.addHeader("Authorization", "Bearer " + login().getAccessToken());
        filterChain.doFilter(request, servletResponse);
    }

    public KeycloakAccessToken login() {
        // 登陸引數省略
        var result = kcUserClient.login(authTokenRequest);
        return result;
    }
}

WebMvcConfigurer里注冊

對/add介面進行配置

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Resource
    private CustomFilter customFilter;

    @Bean
    public FilterRegistrationBean<CustomFilter> initFilterRegistrationBean() {
        FilterRegistrationBean<CustomFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(customFilter);
        registrationBean.addUrlPatterns("/add");
        registrationBean.setOrder(0);
        return registrationBean;
    }
}

Feign攔截器的配置

/**
 * @description: Feign內部呼叫時帶上請求頭資訊
 * 注意：要去yml里面改變hystrix Feign的隔離策為strategy: SEMAPHORE
 **/
@Configuration
public class FeignConfiguration implements RequestInterceptor {

    @Override
    public void apply(RequestTemplate template) {
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder
                .getRequestAttributes();
        HttpServletRequest request = attributes.getRequest();
        Enumeration<String> headerNames = request.getHeaderNames();
        if (headerNames != null) {
            while (headerNames.hasMoreElements()) {
                String name = headerNames.nextElement();
                String values = request.getHeader(name);
                template.header(name, values);
            }
        }
        Enumeration<String> bodyNames = request.getParameterNames();
        StringBuffer body = new StringBuffer();
        if (bodyNames != null) {
            while (bodyNames.hasMoreElements()) {
                String name = bodyNames.nextElement();
                String values = request.getParameter(name);
                body.append(name).append("=").append(values).append("&");
            }
        }
        if (body.length() != 0) {
            body.deleteCharAt(body.length() - 1);
            template.body(body.toString());
        }
    }
}

上面代碼完成了對/add介面的攔截，通過自動授權，完成對授權介面kcUserClient.addUser();呼叫，

KcUserClient內容

@FeignClient(name = "keycloak", url = "http://192.168.4.26:8080/auth", configuration = KcUserClient.Configuration.class)
public interface KcUserClient {
    @PostMapping("/admin/realms/demo/users")
    ResponseEntity<?> addUser(@RequestBody UserDTO userDTO);

    @RequestMapping(value = "https://www.cnblogs.com/realms/demo/protocol/openid-connect/token",
            method = RequestMethod.POST,
            consumes = "application/x-www-form-urlencoded")
    KeycloakAccessToken login(@RequestBody AuthTokenRequest authTokenRequest);

    /**
     * 轉向器.
     */
    class Configuration {
        @Bean
        Encoder feignFormEncoder(ObjectFactory<HttpMessageConverters> converters) {
            return new SpringFormEncoder(new SpringEncoder(converters));
        }
    }
}

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