短链接管理
创建短链接数据库表
URI、URL和URN区别 :
URI 指的是一个资源 ；URL 用地址定位一个资源； URN 用名称定位一个资源。
举个例子： 去寻找一个具体的人（URI）；如果用地址：XX省XX市XX区...XX单元XX室的主人 就是URL；如果用身份证号+名字去找就是URN（身份证号+名字 无法确认资源的地址） 。 在Java类库中，URI类不包含任何访问资源的方法，只能标识资源。URL类可以访问资源，可以获取指定资源的流信息。
新增短链接
由于describe在java中属于关键字，所以在实体对象中，对于describe属性应当：
记住是加了反引号的！
/*** 描述*/@TableField("`describe`")private String describe;短链接区分大小写：将utf8m64改成utf8，相应的配置也改成utf8 bin。
将长连接hash模到短链接一定会存在冲突的问题，怎么解决？
重置。为了防止死循环，需要设置一个最大的重置次数。
由于海量数据，并且为了防止多次查询数据库，需要去查缓存，所以需要用分布式锁，从而这个用布隆过滤器实现（在用户注册时，同样使用了）。
private final RBloomFilter<String> shortUriCreateCachePenetrationBloomFilter;/*** 创建短链接** @param requestParam* @return*/@Overridepublic ShortLinkCreateRespDTO createShortLink(ShortLinkCreateReqDTO requestParam) {String shortLinkSuffix=generateSuffix(requestParam);String fullShortUrl=requestParam.getDomain()+"/"+shortLinkSuffix;ShortLinkDO shortLinkDO=ShortLinkDO.builder().domain(requestParam.getDomain()).originUrl(requestParam.getOriginUrl()).gid(requestParam.getGid()).createdType(requestParam.getCreatedType()).validDateType(requestParam.getValidDateType()).validDate(requestParam.getValidDate()).describe(requestParam.getDescribe()).shortUri(shortLinkSuffix).enableStatus(0).fullShortUrl(fullShortUrl).build();try{//数据库如果存在，则会报错，进入catchbaseMapper.insert(shortLinkDO);}catch (DuplicateKeyException exp){//TODO 已经误判的短链接如何处理//第一种，短链接确实真实存在缓存中//第二种，短链接不一定存在缓存中//检查是否存在于数据库中，如果没存在，则说明布隆过滤器误判了。LambdaQueryWrapper<ShortLinkDO> queryWrapper = Wrappers.lambdaQuery(ShortLinkDO.class).eq(ShortLinkDO::getFullShortUrl, fullShortUrl);ShortLinkDO hasShortLinkDO = baseMapper.selectOne(queryWrapper);if(hasShortLinkDO!=null){log.warn("短链接：{} 重复入库",fullShortUrl);throw new ServiceException("短链接生成重复");}}shortUriCreateCachePenetrationBloomFilter.add(fullShortUrl);return ShortLinkCreateRespDTO.builder().fullShortUrl(shortLinkDO.getFullShortUrl()).originUrl(requestParam.getOriginUrl()).gid(requestParam.getGid()).build();}/*** 获取短链接的后缀* @param requestParam* @return*/private String generateSuffix(ShortLinkCreateReqDTO requestParam){int customGenerateCount=0;String shortUri;String originUrl = requestParam.getOriginUrl();while(true){if(customGenerateCount>10){throw new ServiceException("短链接频繁生成，请稍后再试");}//减小当前冲突的可能originUrl+=System.currentTimeMillis();shortUri=HashUtil.hashToBase62(originUrl);if(!shortUriCreateCachePenetrationBloomFilter.contains(requestParam.getDomain()+"/"+shortUri)){break;}customGenerateCount++;}return shortUri;}开发用户登录验证拦截器返回友好提示信息：
@RequiredArgsConstructor
public class UserTransmitFilter implements Filter {private final StringRedisTemplate stringRedisTemplate;private static final List<String> IGNORE_URI= Lists.newArrayList("/api/short-link/admin/v1/user/login","/api/short-link/admin/v1/user/has-username");@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;String requestURI=httpServletRequest.getRequestURI();if(!IGNORE_URI.contains(requestURI)){String method=httpServletRequest.getMethod();if(!(Objects.equals(requestURI,"/api/short-link/admin/v1/user")&&Objects.equals(method,"POST"))){String username = httpServletRequest.getHeader("username");String token = httpServletRequest.getHeader("token");if (!StrUtil.isAllNotBlank(username,token)){returnJson(servletResponse,JSON.toJSONString(Results.failure(new ClientException(USER_TOKEN_FAIL))));return;}Object userInfoJsonStr = null;try{userInfoJsonStr=stringRedisTemplate.opsForHash().get("login_" + username, token);if(userInfoJsonStr==null){throw new ClientException(USER_TOKEN_FAIL);}}catch (Exception exp){returnJson(servletResponse,JSON.toJSONString(Results.failure(new ClientException(USER_TOKEN_FAIL))));return;}UserInfoDTO userInfoDTO = JSON.parseObject(userInfoJsonStr.toString(), UserInfoDTO.class);UserContext.setUser(userInfoDTO);}}try {filterChain.doFilter(servletRequest, servletResponse);} finally {UserContext.removeUser();}}private void returnJson(ServletResponse response, String json) {PrintWriter writer = null;response.setCharacterEncoding("UTF-8");response.setContentType("application/json; charset=utf-8");try {writer = response.getWriter();writer.print(json);} catch (IOException e) {} finally {if (writer != null)writer.close();}}}打包工具，在admin和project的pom中添加，用于联调前端，这个打包插件会让打包有一个直接可以启动的spring文件。
<build><finalName>s{project.artifactId</finalName><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><executions><execution><goals><goal>repackage</goal></goals></execution></executions></plugin></plugins></build>分页查询短链接列表
/*** 分页查询短链接** @param requestParam* @return*/@Overridepublic IPage<ShortLinkPageRespDTO> pageShortLink(ShortLinkPageReqDTO requestParam) {LambdaQueryWrapper<ShortLinkDO> queryWrapper = Wrappers.lambdaQuery(ShortLinkDO.class).eq(ShortLinkDO::getGid, requestParam.getGid()).eq(ShortLinkDO::getEnableStatus, 0).eq(ShortLinkDO::getDelFlag, 0);IPage<ShortLinkDO> resultPage = baseMapper.selectPage(requestParam, queryWrapper);return resultPage.convert(eatch-> BeanUtil.toBean(eatch,ShortLinkPageRespDTO.class));}请求的param有三个：gid、current（当前页）、size（每页数量）
由于返回响应中total有问题，这需要添加一个MySQL数据库分页插件：
@Configuration
public class DataBaseConfiguration {/*** 分页插件* @return*/@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor(){MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));return interceptor;}
}