利用自定义注解，解决问题
例1 自定义注解限制请求
场景：前端发起的频繁的请求，导致服务器压力过大。需要对后端接口进行限流处理，每个接口都需要做限流处理的话就会导致代码冗余，此时就可以利用注解进行解决
非注解形式
这里是用于 某个用户点击的次数（结合radis）进行判断，也可以用请求的ip进行判断
核心代码：
//限流,60秒5次
ValueOperations valueOperations = redisTemplate.opsForValue();
String uri = request.getRequestURI();
//captcha = "0"; 这个用于测试
Integer count =(Integer) valueOperations.get(uri+":"+user.getId());
if(count == null){
valueOperations.set(uri+":"+user.getId(),1,60,TimeUnit.SECONDS);
} else if (count<5) {
valueOperations.increment(uri+":"+user.getId());
}else {
return RespBean.error(RespBeanEnum.ACCESS_LIMIT_REAHCED);
}完整代码：
@RequestMapping(value = "/path",method = RequestMethod.GET)
@ResponseBody
public RespBean getPath(User user,Long goodsId,String captcha,HttpServletRequest request){
if(user == null){
return RespBean.error(RespBeanEnum.SESSION_ERROR);
}
//限流,60秒5次
ValueOperations valueOperations = redisTemplate.opsForValue();
String uri = request.getRequestURI();
log.info("uri====:{}",uri);
log.info("qequestIp===={}",request.getRemoteAddr());
log.info("LocalIp===={}",request.getLocalAddr());
//captcha = "0";
Integer count =(Integer) valueOperations.get(uri+":"+user.getId());
if(count == null){
valueOperations.set(uri+":"+user.getId(),1,60,TimeUnit.SECONDS);
} else if (count<5) {
valueOperations.increment(uri+":"+user.getId());
}else {
return RespBean.error(RespBeanEnum.ACCESS_LIMIT_REAHCED);
}
boolean check= orderService.checkCaptcha(user,goodsId,captcha);
if(!check){
return RespBean.error(RespBeanEnum.ERROR_CAPTCHA);
}
String str = orderService.createPath(user,goodsId);
return RespBean.success(str);
}注解形式
注解定义方式，以AcessLimit为例
-
定义注解 AccessLimit
-
创建拦截器 AccessLimitInterceptor
-
在WebConfig 中添加拦截器 addInterceptors
定义注解AccessLimit
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface AccessLimit {
//时间
int second();
//次数
int maxCount();
//这个用于判断是否需要登录，后续可用SpringSecurity + JWT 实现。
boolean needLogin() default true;
}创建拦截器 AccessLimitInterceptor
核心代码：
@Component
public class AccessLimitInterceptor implements HandlerInterceptor {
@Autowired
private RedisTemplate redisTemplate;
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
if(handler instanceof HandlerMethod){
HandlerMethod hm = (HandlerMethod) handler;
AccessLimit accessLimit = hm.getMethodAnnotation(AccessLimit.class);
if( accessLimit ==null){
return true;
}
int second = accessLimit.second();
int maxCount = accessLimit.maxCount();
boolean needLogin = accessLimit.needLogin();
String key = request.getRequestURI();
ValueOperations valueOperations =redisTemplate.opsForValue();
Integer count = (Integer) valueOperations.get(key);
if(count == null){
valueOperations.set(key,1,second, TimeUnit.SECONDS);
} else if (count<maxCount) {
valueOperations.increment(key);
} else {
render(response,RespBeanEnum.ACCESS_LIMIT_REAHCED);
return false;
}
}
return true;
}完整代码：
package com.xxx.seckilldemo.annotation;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.xxx.seckilldemo.config.UserContext;
import com.xxx.seckilldemo.pojo.User;
import com.xxx.seckilldemo.service.IUserService;
import com.xxx.seckilldemo.utils.CookieUtil;
import com.xxx.seckilldemo.vo.RespBean;
import com.xxx.seckilldemo.vo.RespBeanEnum;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.PrintWriter;
import java.util.concurrent.TimeUnit;
/** 接口限流拦截器
* @author Adzc
* @date 2023/11/15 15:40
*/
@Component
public class AccessLimitInterceptor implements HandlerInterceptor {
@Autowired
private IUserService userService;
@Autowired
private RedisTemplate redisTemplate;
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
if(handler instanceof HandlerMethod){
User user = getUser(request,response);
UserContext.setUser(user);
HandlerMethod hm = (HandlerMethod) handler;
AccessLimit accessLimit = hm.getMethodAnnotation(AccessLimit.class);
if( accessLimit ==null){
return true;
}
int second = accessLimit.second();
int maxCount = accessLimit.maxCount();
//此处是登录相关
boolean needLogin = accessLimit.needLogin();
String key = request.getRequestURI();
if(needLogin){
if (user == null){
render(response, RespBeanEnum.SESSION_ERROR);
return false;
}
key+=":"+user.getId();
}
//在有效时间内，次数的判断
ValueOperations valueOperations =redisTemplate.opsForValue();
Integer count = (Integer) valueOperations.get(key);
if(count == null){
valueOperations.set(key,1,second, TimeUnit.SECONDS);
} else if (count<maxCount) {
valueOperations.increment(key);
} else {
//返回对象的定义
render(response,RespBeanEnum.ACCESS_LIMIT_REAHCED);
return false;
}
}
return true;
}
/**
* 获取当前用户
* @param request
* @param response
* @return
*/
private User getUser(HttpServletRequest request,HttpServletResponse response){
String ticket = CookieUtil.getCookieValue(request,"userTicket");
if (StringUtils.isEmpty(ticket)){
System.out.println("没有获取到用户");
return null;
}
return userService.getUserByCookie(ticket,request,response);
}
/**
* 构建返回对象
* @param response
* @param respBeanEnum
*/
private void render(HttpServletResponse response,RespBeanEnum respBeanEnum) throws IOException {
response.setContentType("application/json");
response.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
RespBean respBean = RespBean.error(respBeanEnum);
out.write(new ObjectMapper().writeValueAsString(respBean));
out.flush();
out.close();
}
}
返回对象用到了枚举
/**
* 公共返回对象
* @author Adzc
* @date 2023/9/25 23:19
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
public class RespBean {
private long code;
private String message;
private Object obj;
/**
* 成功返回结果
* @return
*/
public static RespBean success(){
return new RespBean(RespBeanEnum.SUCCESS.getCode(), RespBeanEnum.SUCCESS.getMessage(),null);
}
public static RespBean success(Object obj){
return new RespBean(RespBeanEnum.SUCCESS.getCode(), RespBeanEnum.SUCCESS.getMessage(),obj);
}
/**
* 失败返回结果
* @param respBeanEnum
* @return
*/
public static RespBean error(RespBeanEnum respBeanEnum){
return new RespBean(respBeanEnum.getCode(), respBeanEnum.getMessage(),null);
}
public static RespBean error(RespBeanEnum respBeanEnum,Object obj){
return new RespBean(respBeanEnum.getCode(), respBeanEnum.getMessage(),obj);
}
}@Getter
@ToString
@AllArgsConstructor
public enum RespBeanEnum {
SUCCESS(200,"SUCCESS"),
ERROR(500,"服务端异常"),
//登录模块
LOGIN_ERROR(500210,"用户名或密码不正确"),
MOBILE_ERROR(500211,"非法手机号"),
BIND_ERROR(500212,"参数校验异常"),
MOBILE_NOT_EXIST(500213, "手机号不存在"),
PASSWORD_UPDATE_FAIL(500214,"密码更新失败"),
SESSION_ERROR(500215,"用户不存在"),
ACCESS_LIMIT_REAHCED(500504,"访问过于频繁请稍后在尝试");
private final Integer code;
private final String message;
}在WebConfig 中添加拦截器 addInterceptors
核心代码
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(accessLimitInterceptor);
}
}完整代码
@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
@Autowired
private AccessLimitInterceptor accessLimitInterceptor;
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(accessLimitInterceptor);
}
}例2 利用@JsonSerialize注解+自定义类进行手机号脱敏处理
场景：很多手机号之类的信息需要在前端页面需要进行脱敏处理
public class PhoneJsonSerializer extends JsonSerializer {
@Override
public void serialize(Object value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
if (value != null && value instanceof String){
if (!Objects.equals(value,"") && value.toString().length() > 5){
String phone = value.toString();
phone = phone.substring(0, 3) + "******" + phone.substring(phone.length() - 2);
gen.writeString(phone);
} else {
gen.writeObject(value);
}
} else {
gen.writeObject(value);
}
}
}在返回的对象中使用
@JsonSerialize(using = PhoneJsonSerializer.class)
private String phone;
