HandlerMethodArgumentResolver（自定义参数解析器）

 

每个接口在被调用时，很可能需要调用该接口的用户信息，每次再去数据库查询该数据信息，势必会造成代码的大量重复，且还容易出错。 

应用：把该次调用者用户的信息当做参数传到对应的方法。

比如：根据token获得到用户信息，将用户信息传到对应请求的method。

实现自定义参数解析器步骤：1、自定义注解   2、自定义参数解析器   3、注册

自定义注解 

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
@Documented
public @interface UserToken {

}

自定义参数解析器

@Component
public class TokenResolver implements HandlerMethodArgumentResolver {

    @Autowired
    private UserMapper userMapper;

    @Override
    public boolean supportsParameter(MethodParameter methodParameter) {
        if(methodParameter.hasParameterAnnotation(UserToken.class)){
            return true;
        }
        return false;
    }

    @Override
    public Object resolveArgument(MethodParameter methodParameter, ModelAndViewContainer modelAndViewContainer, NativeWebRequest nativeWebRequest, WebDataBinderFactory webDataBinderFactory) throws Exception {
        HttpServletRequest request = nativeWebRequest.getNativeRequest(HttpServletRequest.class);
        String token = request.getHeader("token");
        if(StringUtils.isEmpty(token)){
            return null;
        }
        User user = userMapper.selectOneUser(Integer.parseInt(token));
        return user;
    }
}

注册自定义参数解析器

@Configuration
public class MyWebMvcConfigurerAdapter extends WebMvcConfigurerAdapter {

    @Autowired
    private TokenResolver tokenResolver;

    //@Override
    //public void addInterceptors(InterceptorRegistry registry) {
        //registry.addInterceptor(new TokenInterceptor()).addPathPatterns("/user/*").excludePathPatterns("/user/getone2");
    //}

    @Override
    public void addArgumentResolvers(List argumentResolvers) {
        argumentResolvers.add(tokenResolver);
    }
}

Controller 

@RestController
public class UserController {
    
    @GetMapping("/test/testHandlerMethodArgumentResolver")
    public User testHandlerMethodArgumentResolver(@UserToken User user){
        return user;
    }
}

返回数据