springboot基於redis的分佈式鎖代碼

分佈式鎖，當前代碼中， 會循環嘗試執行獲取鎖對象，每一秒一次。

如果鎖沒有釋放而退出，會導致死鎖的現象， 在看官的場合中，可以對while做調整 退出循環。 例如嘗試5次失敗則退出。

import com.kakacl.product_service.config.Constant;
import com.kakacl.product_service.config.Constants;
import com.kakacl.product_service.controller.BaseController;
import com.kakacl.product_service.service.BackCardService;
import com.kakacl.product_service.utils.ErrorCode;
import com.kakacl.product_service.utils.Resp;
import org.apache.commons.lang.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletRequest;
import java.util.*;

/**
 * @author wangwei
 * @version v1.0.0
 * @description 我的收入控制器
 * @date 2019-01-11
 */
@RestController
@RequestMapping("/api/rest/{version}/myincome")
public class MyInComeController extends BaseController {

    @Autowired
    private BackCardService backCardService;

    @Autowired
    private StringRedisTemplate stringRedisTemplate;

    // 添加銀行卡的同步鎖
    private final static String countKey="redis:lock:add_back_num";

   
    @RequestMapping(value = "addBackCard", method = RequestMethod.POST, consumes = MediaType.APPLICATION_JSON_UTF8_VALUE)
    public Resp addBackCard(HttpServletRequest request,
                            @RequestParam(name = "time", required = true)String time,
                            String token,
                            @RequestParam(name = "cardNum", required = true) String cardNum,
                            String name,
                            String phoneNum,
                            String idCard,
                            String opanCardBack) {
        Map params = new HashMap<>();
        String userId = getUserid(request);
        System.out.println(userId);

        // TODO 只有噹噹前key不存在的時候，SETNX 會成功 – 此時相當於獲取到可以對這個資源進行操作的同步鎖
        final String key=String.format("redis:add_card_num:id:%s", userId +"");
        Boolean res = true;
        while(res){
            String value = UUID.randomUUID().toString()+System.nanoTime();
            res = stringRedisTemplate.opsForValue().setIfAbsent(key,value);
            if (res) {
                stringRedisTemplate.opsForValue().increment(countKey, 1L);
                try {
                    // 執行業務
                    res = false;

                    // 1.查詢用戶是否已經綁定過相同的銀行卡,根據銀行卡判斷
                    params.put("card_num", cardNum);
                    List<Map>  result = backCardService.selectBackCarcdExist(params);
                    if(result != null && result.size() > Constants.CONSTANT_0) {
                        // 已經有綁定過
                        log.info("基於redis實戰分佈式鎖-成功：stock={} 這個銀行卡已經有賬戶綁定過 ",cardNum);
                        return Resp.fail(ErrorCode.CODE_6010);
                    } else {
                        // 繼續執行
                        log.info("繼續執行：stock={}  ",cardNum);

                        return Resp.success();

                    }
                } catch (Exception e) {
                    return Resp.fail();
                } finally {
                    //TODO：釋放鎖-釋放當時自己獲取到的鎖-value
                    String redisValue = stringRedisTemplate.opsForValue().get(key);
                    if (StringUtils.isNotBlank(redisValue) && redisValue.equals(value)){
                        stringRedisTemplate.delete(key);
                    }
                }
            } else{
                res=true;
                try{
                    Thread.sleep(1000L);
                } catch (Exception e) {}
            }
        }

        return Resp.fail(ErrorCode.CODE_9999);
    }
}