springboot自定义参数解析HandlerMethodArgumentResolver

自定义解析器需要实现HandlerMethodArgumentResolver接口，HandlerMethodArgumentResolver接口包含两个接口函数：

public interface HandlerMethodArgumentResolver {
    boolean supportsParameter(MethodParameter var1);

    @Nullable
    Object resolveArgument(MethodParameter var1, @Nullable ModelAndViewContainer var2, NativeWebRequest var3, @Nullable WebDataBinderFactory var4) throws Exception;
}

自定义一个解析器 UserArgumentResolver

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.MethodParameter;
import org.springframework.stereotype.Service;
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;

import com.imooc.miaosha.access.UserContext;
import com.imooc.miaosha.domain.MiaoshaUser;
import com.imooc.miaosha.service.MiaoshaUserService;
/**
 *
 * @Description: 自定义解析器   从Session、数据库或者缓存中查。
 * @param: 
 * @return: 
 * @date: 2019/6/26 8:32
 */
@Service
public class UserArgumentResolver implements HandlerMethodArgumentResolver {

	
	@Override
	public boolean supportsParameter(MethodParameter parameter) {
		Class clazz = parameter.getParameterType();
		return clazz==MiaoshaUser.class;
	}

	@Override
	public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
								  NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
		return UserContext.getUser();
	}

}

 

其中UserContext 是保存当前线程用户的类

import com.imooc.miaosha.domain.MiaoshaUser;

public class UserContext {
	
	private static ThreadLocal userHolder = new ThreadLocal();
	
	public static void setUser(MiaoshaUser user) {
		userHolder.set(user);
	}
	
	public static MiaoshaUser getUser() {
		return userHolder.get();
	}

}

为了达到限流目的使用的注解

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Retention(RUNTIME)
@Target(METHOD)
public @interface AccessLimit {
	int seconds();
	int maxCount();
	boolean needLogin() default true;
}

 

定义一个拦截器   1. 获取token-> 从redis回去用户信息注入方法参数中 

2. redisSerice  等于一个redisTemple  可以自由显示添加 删除 缓存操作，这里就不在重复写了

3.  accessLimit.seconds();  获取缓存过期时间，设置到redis中    accessLimit.maxCount(); 获取过期时间内访问的数目

配置拦截器适配器 拦截注入

import com.alibaba.fastjson.JSON;
import com.imooc.miaosha.domain.MiaoshaUser;
import com.imooc.miaosha.redis.AccessKey;
import com.imooc.miaosha.redis.RedisService;
import com.imooc.miaosha.result.CodeMsg;
import com.imooc.miaosha.result.Result;
import com.imooc.miaosha.service.MiaoshaUserService;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.OutputStream;

@Service
public class AccessInterceptor  extends HandlerInterceptorAdapter{
	
	@Autowired
	MiaoshaUserService userService;
	
	@Autowired
	RedisService redisService;
	
	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		if(handler instanceof HandlerMethod) {
			MiaoshaUser user = getUser(request, response);
			UserContext.setUser(user);
			HandlerMethod hm = (HandlerMethod)handler;
			AccessLimit accessLimit = hm.getMethodAnnotation(AccessLimit.class);
			if(accessLimit == null) {
				return true;
			}
			int seconds = accessLimit.seconds();
			int maxCount = accessLimit.maxCount();
			boolean needLogin = accessLimit.needLogin();
			String key = request.getRequestURI();
			if(needLogin) {
				if(user == null) {
					render(response, CodeMsg.SESSION_ERROR);
					return false;
				}
				key += "_" + user.getId();
			}else {
				//do nothing
			}
			AccessKey ak = AccessKey.withExpire(seconds);//获取指定前缀
			Integer count = redisService.get(ak, key, Integer.class);
	    	if(count  == null) {
	    		 redisService.set(ak, key, 1);
	    	}else if(count < maxCount) {
	    		 redisService.incr(ak, key);
	    	}else {
	    		render(response, CodeMsg.ACCESS_LIMIT_REACHED);
	    		return false;
	    	}
		}
		return true;
	}
	private void render(HttpServletResponse response, CodeMsg cm)throws Exception {
		response.setContentType("application/json;charset=UTF-8");
		OutputStream out = response.getOutputStream();
		String str  = JSON.toJSONString(Result.error(cm));
		out.write(str.getBytes("UTF-8"));
		out.flush();
		out.close();
	}
    private MiaoshaUser getUser(HttpServletRequest request, HttpServletResponse response) {
		String paramToken = request.getParameter(MiaoshaUserService.COOKI_NAME_TOKEN);
		String cookieToken = getCookieValue(request, MiaoshaUserService.COOKI_NAME_TOKEN);
		if(StringUtils.isEmpty(cookieToken) && StringUtils.isEmpty(paramToken)) {
			return null;
		}
		String token = StringUtils.isEmpty(paramToken)?cookieToken:paramToken;
		return userService.getByToken(response, token);
	}
	
	private String getCookieValue(HttpServletRequest request, String cookiName) {
		Cookie[]  cookies = request.getCookies();
		if(cookies == null || cookies.length <= 0){
			return null;
		}
		for(Cookie cookie : cookies) {
			if(cookie.getName().equals(cookiName)) {
				return cookie.getValue();
			}
		}
		return null;
	}
	
}

配置拦截器适配器 拦截注入

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
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.WebMvcConfigurerAdapter;

import com.imooc.miaosha.access.AccessInterceptor;

@Configuration
public class WebConfig  extends WebMvcConfigurerAdapter{
	
	@Autowired
	UserArgumentResolver userArgumentResolver;
	
	@Autowired
	AccessInterceptor accessInterceptor;
	
	@Override
	public void addArgumentResolvers(List argumentResolvers) {
		argumentResolvers.add(userArgumentResolver);
	}
	
	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		registry.addInterceptor(accessInterceptor);
	}
	
}