springboot-HandlerMethodArgumentResolver解析自定義註解

1.自定義註解

package com.zhong.spring_demo.anno;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

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

    String value() default "user";
}

2.編寫自定義參數解析器，CurrentUserMethodArgumentResolver實現HandlerMethodArgumentResolver

package com.zhong.spring_demo.intercepter;

import com.zhong.spring_demo.anno.CurrentUser;
import com.zhong.spring_demo.entity.User;

import org.springframework.core.MethodParameter;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;

/**
 * CurrentUserMethodArgumentResolver
 */
public class CurrentUserMethodArgumentResolver implements HandlerMethodArgumentResolver {

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        return parameter.hasParameterAnnotation(CurrentUser.class)
                && User.class.isAssignableFrom(parameter.getParameterType());
    }

    @Override
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
            NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
        CurrentUser currentUserAnnotation = parameter.getParameterAnnotation(CurrentUser.class);
        
        // 從Session 獲取用戶
        Object object = webRequest.getAttribute(currentUserAnnotation.value(), NativeWebRequest.SCOPE_SESSION);
        // 從 accessToken獲得用戶信息
        if (object == null) {
            String token = webRequest.getHeader("Authorization");
            if (token == null) {
                token = webRequest.getParameter("accessToken");
            }

            // 爲了測試先寫死用戶名
            // TODO: 取真實用戶
            return new User();
        }
        return object;
    }

}

3.進行配置

package com.zhong.spring_demo.config;

import java.util.List;


import com.zhong.spring_demo.intercepter.CurrentUserMethodArgumentResolver;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * 註冊外部的interceptor WebConfig
 */
@Configuration
public class WebConfig implements WebMvcConfigurer {


    /**
     * 配置外部HandlerMethodArgumentResolver
     */
    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        argumentResolvers.add(new CurrentUserMethodArgumentResolver());
    }

}