三级菜单加缓存及增加本地锁方案（适用于单体应用模式。不适合分布式）

kkmall-gateway/src/main/resources/application.yml

@@ -54,7 +54,7 @@ spring:
           filters:
             - RewritePath=/api/(?<segment>.*), /renren-fast/$\{segment}
 
-        # 任何以mall.com结尾的域名转发到mall-product
+        # 任何以kkmall.com结尾的域名转发到kkmall-product
         # 注意！！！Nginx代理给网关的时候，会丢失请求Host
         - id: kkmall_route
           uri: lb://kkmall-product

kkmall-product/pom.xml

@@ -42,6 +42,11 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-thymeleaf</artifactId>
         </dependency>
+<!--        使用Redis-->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-redis</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-devtools</artifactId>

kkmall-product/src/main/java/name/lkk/kkmall/product/service/impl/CategoryServiceImpl.java

@@ -1,5 +1,7 @@
 package name.lkk.kkmall.product.service.impl;
 
+import com.alibaba.fastjson.JSON;
+import com.alibaba.fastjson.TypeReference;
 import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
 import com.baomidou.mybatisplus.core.metadata.IPage;
 import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
@@ -12,10 +14,15 @@ import name.lkk.kkmall.product.service.CategoryService;
 import name.lkk.kkmall.product.vo.Catalog3Vo;
 import name.lkk.kkmall.product.vo.Catelog2Vo;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.redis.core.StringRedisTemplate;
+import org.springframework.data.redis.core.ValueOperations;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 import java.util.*;
+import java.util.concurrent.TimeUnit;
 import java.util.stream.Collectors;
 
 
@@ -25,6 +32,9 @@ public class CategoryServiceImpl extends ServiceImpl<CategoryDao, CategoryEntity
     @Autowired
     private CategoryBrandRelationService categoryBrandRelationService;
 
+    @Autowired
+    private StringRedisTemplate stringRedisTemplate;
+
     @Override
     public PageUtils queryPage(Map<String, Object> params) {
         IPage<CategoryEntity> page = this.page(
@@ -102,9 +112,47 @@ public class CategoryServiceImpl extends ServiceImpl<CategoryDao, CategoryEntity
         return entityList.stream().filter(item -> item.getParentCid().equals(parentCid)).collect(Collectors.toList());
     }
 
+    /**
+     * 从缓存中查询CatelogJson
+     * @return
+     */
     @Override
     public Map<String, List<Catelog2Vo>> getCatelogJson() {
+
+        /**
+         * 1.空结果缓存 解决缓存穿透
+         * 2.设置过期时间(加随机值) 解决缓存雪崩
+         * 3.加锁 解决缓存击穿
+         */
+        ValueOperations<String, String> operations = stringRedisTemplate.opsForValue();
+        Map<String, List<Catelog2Vo>> catelogJson;
+        // 缓存中没有数据
+        String catelogJSON = operations.get("catelogJSON");
+        if (ObjectUtils.isEmpty(catelogJSON)) {
+
+            catelogJson = getCatelogJsonFromDBWithLocalLock();
+        } else {
+            System.out.println("缓存命中。。。查询缓存");
+            catelogJson = JSON.parseObject(catelogJSON, new TypeReference<Map<String, List<Catelog2Vo>>>() {
+            });
+        }
+        return catelogJson;
+    }
+
+    /**
+     * 从数据库中查询CatelogJson
+     * @return
+     */
+    public Map<String, List<Catelog2Vo>> getCatelogJsonFormDB() {
+
+        String catelogJSON = stringRedisTemplate.opsForValue().get("catelogJSON");
+        if (!ObjectUtils.isEmpty(catelogJSON)) {
+            return JSON.parseObject(catelogJSON, new TypeReference<Map<String, List<Catelog2Vo>>>() {
+            });
+        }
+        // 优化：将查询变为一次
         List<CategoryEntity> entityList = baseMapper.selectList(null);
+
         // 查询所有一级分类
         List<CategoryEntity> level1 = getCategoryEntities(entityList, 0L);
         Map<String, List<Catelog2Vo>> parent_cid = level1.stream().collect(Collectors.toMap(k -> k.getCatId().toString(), v -> {
@@ -126,9 +174,53 @@ public class CategoryServiceImpl extends ServiceImpl<CategoryDao, CategoryEntity
             }
             return catelog2Vos;
         }));
+        // 优化：查询到数据库就在锁还没结束之前放入缓存
+        stringRedisTemplate.opsForValue().set("catelogJSON", JSON.toJSONString(parent_cid), 1, TimeUnit.DAYS);
         return parent_cid;
     }
 
+    /**
+     * redis没有数据 查询DB [本地锁解决方案]
+     */
+    public Map<String, List<Catelog2Vo>> getCatelogJsonFromDBWithLocalLock() {
+        String catelogJSON = stringRedisTemplate.opsForValue().get("catelogJSON");
+        if (!ObjectUtils.isEmpty(catelogJSON)) {
+            return JSON.parseObject(catelogJSON, new TypeReference<Map<String, List<Catelog2Vo>>>() {
+            });
+        }
+        synchronized (this) {
+            System.out.println("缓存未命中。。。查询数据库。[本地锁解决方案]");
+
+            // 优化：将查询变为一次
+            List<CategoryEntity> entityList = baseMapper.selectList(null);
+
+            // 查询所有一级分类
+            List<CategoryEntity> level1 = getCategoryEntities(entityList, 0L);
+            Map<String, List<Catelog2Vo>> parent_cid = level1.stream().collect(Collectors.toMap(k -> k.getCatId().toString(), v -> {
+                // 拿到每一个一级分类 然后查询他们的二级分类
+                List<CategoryEntity> entities = getCategoryEntities(entityList, v.getCatId());
+                List<Catelog2Vo> catelog2Vos = null;
+                if (entities != null) {
+                    catelog2Vos = entities.stream().map(l2 -> {
+                        Catelog2Vo catelog2Vo = new Catelog2Vo(v.getCatId().toString(), l2.getName(), l2.getCatId().toString(), null);
+                        // 找当前二级分类的三级分类
+                        List<CategoryEntity> level3 = getCategoryEntities(entityList, l2.getCatId());
+                        // 三级分类有数据的情况下
+                        if (level3 != null) {
+                            List<Catalog3Vo> catalog3Vos = level3.stream().map(l3 -> new Catalog3Vo(l3.getCatId().toString(), l3.getName(), l2.getCatId().toString())).collect(Collectors.toList());
+                            catelog2Vo.setCatalog3List(catalog3Vos);
+                        }
+                        return catelog2Vo;
+                    }).collect(Collectors.toList());
+                }
+                return catelog2Vos;
+            }));
+            // 优化：查询到数据库就在锁还没结束之前放入缓存
+            stringRedisTemplate.opsForValue().set("catelogJSON", JSON.toJSONString(parent_cid), 1, TimeUnit.DAYS);
+            return parent_cid;
+        }
+    }
+
     /**
      * 递归收集所有节点
      */

kkmall-product/src/main/resources/application.yml

@@ -5,7 +5,6 @@ spring:
     url: jdbc:mysql://localhost:3306/kkmall_pms?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai
     username: root
     password: 66CcFf!!
-
   cloud:
     nacos:
       discovery:
@@ -19,6 +18,10 @@ spring:
     static-path-pattern: /static/**
   thymeleaf:
     cache: true
+  redis:
+    host: localhost
+    port: 6379
+    password: linkekun
 
 mybatis-plus:
   mapper-locations: classpath:/mapper/**/*.xml
@@ -32,3 +35,7 @@ mybatis-plus:
     #log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
 server:
   port: 10000
+
+logging:
+  level:
+    name.lkk.kkmall: error

kkmall-product/src/test/java/name/lkk/kkmall/product/KkmallProductApplicationTests.java

@@ -2,9 +2,14 @@ package name.lkk.kkmall.product;
 
 import name.lkk.kkmall.product.entity.BrandEntity;
 import name.lkk.kkmall.product.service.impl.BrandServiceImpl;
+import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.data.redis.core.StringRedisTemplate;
+import org.springframework.data.redis.core.ValueOperations;
+
+import java.util.UUID;
 
 @SpringBootTest
 class KkmallProductApplicationTests {
@@ -12,6 +17,17 @@ class KkmallProductApplicationTests {
     @Autowired
     BrandServiceImpl brandService;
 
+    @Autowired
+    StringRedisTemplate stringRedisTemplate;
+
+    @Test
+    @DisplayName("测试StringRedisTemplate")
+    public void TestStringRedisTemplate(){
+        ValueOperations<String, String> stringStringValueOperations = stringRedisTemplate.opsForValue();
+        stringStringValueOperations.set("Hello","KK"+ UUID.randomUUID());
+        System.out.println(stringStringValueOperations.get("Hello"));
+    }
+
     @Test
     void contextLoads() {
 //        BrandEntity brandEntity = new BrandEntity();