成员变量为动态数据时不可轻易使用

量为动态数据时不可轻易使用"/>

成员变量为动态数据时不可轻易使用

问题描述

业务验收阶段，遇到了一个由于成员变量导致的线程问题

有一个kafka切面，用来处理某些功能在调用前后的发送消息，资产类型type是成员变量定义；

资产1类型推送消息是以zichan1为节点；资产2类型推送消息是以zichan2为节点；

当多个线程调用切面类时，由于切面类中使用成员变量且为动态数据时，此时会出现根据资产类型推送消息错误；例如资产1在调用功能时，切面类的type字段为zichan1；同时有资产2调用功能时，此时的切面类的type字段为zichan2;导致资产1在调用功能前推送的是zichan1,在调用功能后推送的是zichan2的消息标识。

原因

当多个线程同时调用时，成员变量则会只采用最后一次调用的值。

下面简单描述下情景：

kafkaAspect类

import com.alibaba.fastjson.JSON;
import com.example.demo.constant.StageCodeConstant;
import com.example.demo.entity.KafkaSendMessageConstant;
import com.example.demo.util.DateUtils;
import lombok.extern.slf4j.Slf4j;
import org.apachemons.lang.ArrayUtils;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;@Component
@Aspect
@Slf4j
public class KafkaProcessAspect {private static final Logger log = LoggerFactory.getLogger(KafkaProcessAspect.class);private String assetType = "";private String startTime = "";@Around("@annotation(kafkaProcess)")public Object doAround(ProceedingJoinPoint joinPoint, KafkaProcess kafkaProcess) throws Throwable {Object object = null;assetType = (String) getParamValue(joinPoint, "assetType");startTime = DateUtils.getTime();object = joinPoint.proceed();//推送消息String stageCode = StageCodeConstant.STAGE_CODE.get(assetType).get(kafkaProcess.functionName());KafkaSendMessageConstant messageConstant = new KafkaSendMessageConstant();messageConstant.setStageCode(stageCode);messageConstant.setStartTime(startTime);messageConstant.setEndTime(DateUtils.getTime());log.info("资产类型{}推送消息：{}", assetType, JSON.toJSONString(messageConstant));return object;}private Object getParamValue(ProceedingJoinPoint joinPoint, String paramName) {Object[] params = joinPoint.getArgs();String[] parameterNames = ((MethodSignature) joinPoint.getSignature()).getParameterNames();if (parameterNames == null || parameterNames.length == 0) {return null;}for (String param : parameterNames) {if (param.equals(paramName)) {int index = ArrayUtils.indexOf(parameterNames, param);return params[index];}}return null;}}

 由于controller中的请求地址是采用占位符定义，后使用@PathVariable可以获取的类型

Controller类

import com.example.demo.aop.KafkaProcess;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
@RequestMapping("/test")
public class TestController {private static final Logger logger = LoggerFactory.getLogger(TestController.class);@PostMapping("/{assetType}/cmpt")@KafkaProcess(functionName = "JS")public void cmpt(@PathVariable("assetType") String assetType) {logger.info("{}接口开始", assetType);long startTime = System.currentTimeMillis();for (int i = 0; i < 20000; i++) {for (int j = 0; j < 20000; j++) {int m = i * j;logger.debug("i*j={}",m);}}long endTime = System.currentTimeMillis();logger.info("{}接口结束,耗时{}", assetType, endTime - startTime);}}

 资产类型枚举 AssetTypeEnum

public enum AssetTypeEnum {ZICHAN_1("zichan1","资产1"),ZICHAN_2("zichan2","资产2");// 成员变量private String code;private String desc;public String getCode() {return code;}public void setCode(String code) {this.code = code;}public String getDesc() {return desc;}public void setDesc(String desc) {this.desc = desc;}// 构造方法AssetTypeEnum(String code,String desc) {this.code = code;this.desc = desc;}}

推送消息 KafkaSendMessageConstant

public class KafkaSendMessageConstant {private String stageCode;private String startTime;private String endTime;public String getStageCode() {return stageCode;}public void setStageCode(String stageCode) {this.stageCode = stageCode;}public String getStartTime() {return startTime;}public void setStartTime(String startTime) {this.startTime = startTime;}public String getEndTime() {return endTime;}public void setEndTime(String endTime) {this.endTime = endTime;}
}

节点常量类 StageCodeConstant ；根据不同资产类型赋值不同功能的推送标识

import java.util.HashMap;
import java.util.Map;public class StageCodeConstant {public static final Map<String, Map<String, String>> STAGE_CODE = new HashMap<>();static {//资产1STAGE_CODE.put(AssetTypeEnum.ZICHAN_1.getCode(),new HashMap<String, String>() {{put("JS", "ZICHAN1-JS");}});//资产2STAGE_CODE.put(AssetTypeEnum.ZICHAN_2.getCode(),new HashMap<String, String>() {{put("JS", "ZICHAN2-JS");}});}
}

用postman调用资产2接口

后立即调用资产1接口

此时出现这种结果：

会发现，调用资产2的时候发送消息还是资产1的信息；然后资产1发送的消息也是资产1的信息

解决

此时有两个解决办法，一个是将doAround()和其他方法合并为一个方法，将成员变量调整为局部变量；另一个则为将该成员变量设置为一个对象，对这个对象进行线程设置，保证doAround()和doBefore()获取的是同一个对象的数据

解决方法一

import com.alibaba.fastjson.JSON;
import com.example.demo.constant.StageCodeConstant;
import com.example.demo.entity.KafkaSendMessageConstant;
import com.example.demo.util.DateUtils;
import lombok.extern.slf4j.Slf4j;
import org.apachemons.lang.ArrayUtils;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;@Component
@Aspect
@Slf4j
public class KafkaProcessAspect {private static final Logger log = LoggerFactory.getLogger(KafkaProcessAspect.class);@Around("@annotation(kafkaProcess)")public Object doAround(ProceedingJoinPoint joinPoint, KafkaProcess kafkaProcess) throws Throwable {Object object = null;String assetType = (String) getParamValue(joinPoint, "assetType");String startTime = DateUtils.getTime();object = joinPoint.proceed();//推送消息String stageCode = StageCodeConstant.STAGE_CODE.get(assetType).get(kafkaProcess.functionName());KafkaSendMessageConstant messageConstant = new KafkaSendMessageConstant();messageConstant.setStageCode(stageCode);messageConstant.setStartTime(startTime);messageConstant.setEndTime(DateUtils.getTime());log.info("资产类型{}推送消息：{}", assetType, JSON.toJSONString(messageConstant));return object;}private Object getParamValue(ProceedingJoinPoint joinPoint, String paramName) {Object[] params = joinPoint.getArgs();String[] parameterNames = ((MethodSignature) joinPoint.getSignature()).getParameterNames();if (parameterNames == null || parameterNames.length == 0) {return null;}for (String param : parameterNames) {if (param.equals(paramName)) {int index = ArrayUtils.indexOf(parameterNames, param);return params[index];}}return null;}}

解决方法二

成员变量KafkaSingleDTO

public class KafkaSingleDTO {private String assetType="";private String date="";public String getAssetType() {return assetType;}public void setAssetType(String assetType) {this.assetType = assetType;}public String getDate() {return date;}public void setDate(String date) {this.date = date;}
}

对象单实例获取 KafkaSingleUtil

import com.example.demo.entity.KafkaSingleDTO;public class KafkaSingleUtil {private static ThreadLocal<KafkaSingleDTO> START = new ThreadLocal<>();public static KafkaSingleDTO getObject() {KafkaSingleDTO singleDTO = START.get();if (singleDTO == null) {singleDTO = new KafkaSingleDTO();}return singleDTO;}}

kafkaAsspect拦截器

import com.alibaba.fastjson.JSON;
import com.example.demo.constant.StageCodeConstant;
import com.example.demo.entity.KafkaSendMessageConstant;
import com.example.demo.entity.KafkaSingleDTO;
import com.example.demo.util.DateUtils;
import lombok.extern.slf4j.Slf4j;
import org.apachemons.lang.ArrayUtils;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;@Component
@Aspect
@Slf4j
public class KafkaProcessAspect {private static final Logger log = LoggerFactory.getLogger(KafkaProcessAspect.class);private static String assetType="";private static String startTime="";@Around("@annotation(kafkaProcess)")public Object doAround(ProceedingJoinPoint joinPoint, KafkaProcess kafkaProcess) throws Throwable {Object object = null;assetType = (String) getParamValue(joinPoint, "assetType");startTime = DateUtils.getTime();KafkaSingleDTO singleDTO = KafkaSingleUtil.getObject();singleDTO.setAssetType(assetType);singleDTO.setDate(startTime);object = joinPoint.proceed();//推送消息--方法调用后String stageCode = StageCodeConstant.STAGE_CODE.get(singleDTO.getAssetType()).get(kafkaProcess.functionName());KafkaSendMessageConstant messageConstant = new KafkaSendMessageConstant();messageConstant.setStageCode(stageCode);messageConstant.setStartTime(singleDTO.getDate());messageConstant.setEndTime(DateUtils.getTime());log.info("资产类型{}方法后推送消息：{}", singleDTO.getAssetType(), JSON.toJSONString(messageConstant));return object;}@Before("@annotation(kafkaProcess)")public void doBefore(KafkaProcess kafkaProcess){//推送消息--方法调用前KafkaSingleDTO singleDTO = KafkaSingleUtil.getObject();singleDTO.setAssetType(assetType);String stageCode = StageCodeConstant.STAGE_CODE.get(singleDTO.getAssetType()).get(kafkaProcess.functionName());KafkaSendMessageConstant messageConstant = new KafkaSendMessageConstant();messageConstant.setStageCode(stageCode);//...消息实体类 可自补充log.info("资产类型{}方法前推送消息：{}", singleDTO.getAssetType(), JSON.toJSONString(messageConstant));}private Object getParamValue(ProceedingJoinPoint joinPoint, String paramName) {Object[] params = joinPoint.getArgs();String[] parameterNames = ((MethodSignature) joinPoint.getSignature()).getParameterNames();if (parameterNames == null || parameterNames.length == 0) {return null;}for (String param : parameterNames) {if (param.equals(paramName)) {int index = ArrayUtils.indexOf(parameterNames, param);return params[index];}}return null;}
}

最终结果：

到此结束！