java - 自定义注释，用于从 HttpServletRequest 获取具有指定 @RequestHeaders 集的自定义对象

Question

我正在寻找创建自定义注释以从 HttpServletRequest 读取 header 集的方法

假设我有以下代码:

@RestController
public class ExampleController {

    @PostMapping(path = "/path")
    public void method(@RequestHeader("session-session_id") long sessionId,
                       @RequestHeader("session-user_id") long userId,
                       @RequestHeader("session-user_name") String userName) {
        UserInfo userInfo = UserInfo.of(sessionId, userId, userName);
        //service.handle(userInfo);
    }

    public static final class UserInfo {
        private final long sessionId;
        private final long userId;
        private final String userName;

        private UserInfo(long sessionId, long userId, String userName) {
            this.sessionId = sessionId;
            this.userId = userId;
            this.userName = userName;
        }

        public static UserInfo of(long sessionId, long userId, String userName) {
            return new UserInfo(sessionId, userId, userName);
        }
    }
} 

如您所见，我在请求 header 中有用户信息。所有用户信息 header 都将以“session-”前缀开头。在真实的系统上我将有超过 3 个字段。它们将用于处理很多请求。因此，我必须将具有完整用户信息的对象转移到服务级别。为每个请求创建这个 UserInfo ，例如 UserInfo.of(sessionId, userId, userName) 看起来多余而且相当丑陋。这就是问题所在。

我至少知道另外两种方法来解决这个问题:

@PostMapping(path = "/path")
public void method(HttpServletRequest request) {
    UserInfo userInfo = UserInfo.of(request);
}

public static UserInfo of(HttpServletRequest request) {
    //request.getHeader("header name");
}

或

@PostMapping(path = "/path")
public void method(@RequestHeader Map<String, String> request) {
    UserInfo userInfo = UserInfo.of(request);
}

public static UserInfo of(Map<String, String> request) {
    //map.get("header name");
}

但事实并非如此。我正在寻找像 spring 那样创建 UserInfo 的方法:

@PostMapping(path = "/path")
public void method(@UserInfo UserInfo request) {
    UserInfo userInfo = UserInfo.of(request);
}

你能帮我解决一下吗？或者至少提供一个文档链接，其中描述了 @RequestHeader 如何在 spring 内实现

Answer 1

您需要定义自定义HandlerMethodArgumentResolver :

public class UserInfoResolver implements HandlerMethodArgumentResolver {

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        return parameter.getParameterType().equals(UserInfo.class);
    }

    @Override
    public Object resolveArgument(MethodParameter parameter,
                                  ModelAndViewContainer mavContainer,
                                  NativeWebRequest webRequest,
                                  WebDataBinderFactory binderFactory) throws Exception {
        // There are no null-checks here for simplicity, 
        // so don't forget to add them in production code
        return UserInfo(
            Long.parseLong(webRequest.getHeader("session-session_id")), 
            Long.parseLong(webRequest.getHeader("session-user_id")),
            webRequest.getHeader("session-user_name")
        );
    }
}

然后让 Spring 了解您的 Web 配置类中的参数解析器:

@Configuration
public class WebApiConfiguration extends WebMvcConfigurationSupport {
    ...

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        argumentResolvers.add(new UserInfoResolver());
    }

    ...
}

最后你可以这样使用它:

@PostMapping(path = "/path")
public void method(UserInfo userInfo) {
    //service.handle(userInfo);
}