详解java解决分布式环境中高并发环境下数据插入重复问题

package com.nursling.web.filter.context;import com.nursling.nosql.redis.RedisUtil;import com.nursling.sign.SignType;import com.nursling.sign.SignUtil;import redis.clients.jedis.Jedis;import javax.servlet.ServletRequest;import javax.servlet.http.HttpServletRequest;import java.util.HashMap;import java.util.Map;/** * 并发拦截 * 高并发下 过滤掉 相同请求的工具 * @author 杨. * */public class ContextLJ {  private static final Integer JD = 0;  /**   * 上锁 使用redis 为分布式项目 加锁   * @param sign   * @param tiD   * @return   * @throws Exception   */  public static boolean lock(String sign, String tiD) {    synchronized (JD) { // 加锁      Jedis jedis = RedisUtil.getJedis();      String uTid = jedis.get(sign);      if (uTid == null) {        jedis.set(sign, tiD);        jedis.expire(sign, 36);        return true;      }      return false;    }  }  /**   * 锁验证   * @param sign   * @param tiD   * @return   */  public static boolean checklock(String sign, String tiD){    Jedis jedis = RedisUtil.getJedis();    String uTid = jedis.get(sign);    return tiD.equals(uTid);  }  /**   * 去掉锁   * @param sign   * @param tiD   */  public static void clent (String sign, String tiD){    if (checklock(sign, tiD)) {      Jedis jedis = RedisUtil.getJedis();      jedis.del(sign);    }  }  /**   * 获取摘要   * @param request   * @return   */  public static String getSign(ServletRequest request){    // 此工具是将 request中的请求内容 拼装成 key=value&key=value2 的形式 源码在线面    Map<String, String> map =       SignUtil.getRequstMap((HttpServletRequest) request);    String sign = null;    try {      // 这里使用md5方法生成摘要 SignUtil.getRequstMap 方法源码就不贴了      sign = SignUtil.buildRequest(map, SignType.MD5);    } catch (Exception e) {      e.printStackTrace();    }    return sign;  }}

public static Map<String, String> getRequstMap(HttpServletRequest req){    Map<String,String> params = new HashMap<String,String>();    Map<String, String[]> requestParams = req.getParameterMap();    for (Iterator<String> iter = requestParams.keySet().iterator(); iter.hasNext();) {      String name = (String) iter.next();      String[] values = (String[]) requestParams.get(name);      String valueStr = "";      for (int i = 0; i < values.length; i++) {        valueStr = (i == values.length - 1) ? valueStr + values[i]            : valueStr + values[i] + ",";      }      params.put(name, valueStr);    }    return params;  }

package com.nursling.web.filter.transaction;import com.google.gson.Gson;import com.nursling.common.RandomUtil;import com.nursling.dao.util.TransactionUtils;import com.nursling.model.ApiResult;import com.nursling.model.ApiRtnCode;import com.nursling.web.filter.context.ContextLJ;import org.apache.log4j.Logger;import javax.servlet.*;import javax.servlet.http.HttpServletResponse;import java.io.IOException;/** * 对事物进行控制 并且 避免接口 直接报漏异常信息 * 并且过滤频繁请求 * Created by yangchao on 2016/11/4. */public class TransactionFilter implements Filter {  Logger log = Logger.getLogger(this.getClass());  @Override  public void init(FilterConfig filterConfig) throws ServletException {  }  @Override  public void doFilter(ServletRequest request, ServletResponse myResp, FilterChain chain) throws IOException, ServletException {    String sign = "sign_" + ContextLJ.getSign(request); // 生成摘要    String tiD = RandomUtil.getRandomString(3) + "_" + Thread.currentThread().getId(); // 当前线程的身份    try {       if (!ContextLJ.lock(sign, tiD)) {        log.warn("放弃相同 并发请求" + sign);        frequentlyError(myResp);        return;      }      if (!ContextLJ.checklock(sign, tiD)) {        log.warn("加锁验证失败 " + sign + " " + tiD);        frequentlyError(myResp);        return;      }      chain.doFilter(request, myResp); // 放行    } catch (Exception e) { // 捕获到异常 进行异常过滤      log.error("", e);      retrunErrorInfo(myResp);    } finally {      ContextLJ.clent(sign, tiD);    }  }  /**   * 频繁请求   * @param myResp   */  private void frequentlyError(ServletResponse myResp) throws IOException {    ApiResult<Object> re = new ApiResult<>();    ((HttpServletResponse) myResp).setHeader("Content-type", "text/html;charset=UTF-8");    re.setMsg("稍安勿躁，不要频繁请求");    re.setCode(ApiRtnCode.API_VERIFY_FAIL);    myResp.getWriter().write(new Gson().toJson(re));  }  /**   * 返回异常信息    * @param myResp   */  private void retrunErrorInfo(ServletResponse myResp) throws IOException {    ApiResult<Object> re = new ApiResult<>();    re.setMsg("server error");    // 这里不必理会    re.setCode(ApiRtnCode.SERVICE_ERROR);    myResp.getWriter().write(new Gson().toJson(re));  }  @Override  public void destroy() {  }}