枚举+链对缓存实现以读取为主的请求接口

本文主要是介绍枚举+链对缓存实现以读取为主的请求接口，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

一、需求背景

需要给一份问卷进行授权，授权的角色固定为4类，分别是：农户、企业、金融机构、政府用户，这4类角色定义在字典里面，并且很少改动。这4类角色下面，可能有多个角色，这些角色通过字典的key关联到上述4个类型中的一个;
在新增、编辑问卷的时候，需要把这4类所有的角色都展示出来，供管理员选择。

二、需求分析

由于涉及到的数据很少改动，且主要以查询为主，于是第一想法就是通过 枚举+链对实现,具体实现如下:

三、实现过程

1. 枚举类

import lombok.Getter;
import lombok.Setter;import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Consumer;
import java.util.stream.Stream;import static com.xxx.xxx.utils.StreamUtil.forEachIfPresent;/*** Author:   wxz* Date:     2023.11.29 10:35* Description: 问卷调查授权枚举*/
public enum PaperAuthorRoleEnum {ANONYMITY("un-limit", "不限", Collections.singletonList("")),AGRICULTURAL("member", "农户",Collections.singletonList("member")),ENTERPRISE("enterprises", "企业", Collections.singletonList("agricultural-enterprises")),FINANCIAL_INSTITUTION("finance", "金融机构",FinanceRoleKeys()),GOVERNMENT_USERS("government", "政府用户", GovernmentRoleKeys()),;/*** 角色类型*/@Getterprivate final String type;/*** 角色类型名称*/@Getterprivate final String typeName;/*** 角色id集合*/@Getterprivate final List<String> roleKeys;/*** 角色列表*/@Getterprivate final List<PaperRole> paperRoleList;/*** 角色缓存数据*/private static Map<String, SysRole> roleCache = new ConcurrentHashMap<>();PaperAuthorRoleEnum(String type, String typeName, List<String> roleKeys) {this.type = type;this.typeName = typeName;this.roleKeys = roleKeys;this.paperRoleList = getRolesFromCache(roleKeys);}/*** 根据角色类型查找枚举* @param type 角色类型* @return 类型枚举*/public static PaperAuthorRoleEnum of(String type) {if (type == null) {return null;}PaperAuthorRoleEnum[] values = PaperAuthorRoleEnum.values();for (PaperAuthorRoleEnum a : values) {if (a.type.equals(type)) {return a;}}return null;}/*** 金融机构角色keys*/private static List<String> FinanceRoleKeys() {List<String> list = new ArrayList<>();//银行机构有5个等级for (int i = 1; i < 5; i++) {list.add("bank_level_" + i);}return list;}/*** 政府角色keys*/private static List<String> GovernmentRoleKeys() {return new ArrayList<>(Arrays.asList("collector","government","government-role"));}/*** 获取所有枚举的keys* @return*/private List<String> getAllRolKeys() {List<String> roleKeys = new ArrayList<>();roleKeys.addAll(Collections.singletonList("member"));roleKeys.addAll(Collections.singletonList("agricultural-enterprises"));roleKeys.addAll(FinanceRoleKeys());roleKeys.addAll(GovernmentRoleKeys());return roleKeys;}/*** 从缓存中获取角色列表* @param roleKeys* @return*/private  List<PaperRole> getRolesFromCache(List<String> roleKeys) {List<PaperRole> paperRoles = new ArrayList<>();Set<String> notExitKeys = new HashSet<>();boolean sign = (roleCache == null);//如果已经存在缓存里面,则优先从缓存里面获取if (sign) {notExitKeys.addAll(getAllRolKeys());roleCache = new ConcurrentHashMap<>();} else {roleKeys.forEach(key -> {if (!roleCache.containsKey(key)) {notExitKeys.add(key);} else {PaperRole paperRole =new PaperRole().setRoleId(roleCache.get(key).getRoleId()).setRoleName(roleCache.get(key).getRoleName());paperRoles.add(paperRole);}});}//不存在于缓存的数据,重新从数据库里面查询出来,放在缓存里面if (notExitKeys.size() > 0) {Optional<List<SysRole>> sysRoles =Optional.ofNullable(SpringUtils.getBean(SysRoleMapper.class).selectListByRoleKeys(new ArrayList<>(notExitKeys)));// forEachIfPresent()方法参考:  https://blog.csdn.net/qq_37844454/article/details/134964619forEachIfPresent(sysRoles,item->{roleCache.put(item.getRoleKey(), item);PaperRole paperRole = new PaperRole().setRoleId(item.getRoleId()).setRoleName(item.getRoleName());paperRoles.add(paperRole);});}return paperRoles;}/*** 获取所有的枚举*/public static PaperAuthorRoleEnum[] getValues() {return new PaperAuthorRoleEnum[]{AGRICULTURAL, ENTERPRISE, FINANCIAL_INSTITUTION, GOVERNMENT_USERS};}
}

2. 控制器调用

    //使用线程安装的链对做缓存,避免读多写少的数据频繁请求数据库private static ConcurrentLinkedQueue<PaperAuthorTypeDTO> dtoQueue = new ConcurrentLinkedQueue<>();@GetMapping(value = "/getRoleList")public AjaxResult getRoleList() {if (CollectionUtils.isEmpty(dtoQueue)) {dtoQueue = new ConcurrentLinkedQueue<>();Arrays.stream(PaperAuthorRoleEnum.getValues()).forEach(anEnum->{dtoQueue.offer(new PaperAuthorTypeDTO().setRoleId(anEnum.getType()).setRoleName(anEnum.getTypeName()));});}return AjaxResult.success(dtoQueue);}