Spring Boot 入门之缓存和 NoSQL 篇（四）-工具盒子

一、前言 {#一、前言}

当系统的访问量增大时，相应的数据库的性能就逐渐下降。但是，大多数请求都是在重复的获取相同的数据，如果使用缓存，将结果数据放入其中可以很大程度上减轻数据库的负担，提升系统的响应速度。

本篇将介绍 Spring Boot 中缓存和 NoSQL 的使用。上篇文章《Spring Boot 入门之持久层篇（三）》。

二、整合缓存 {#二、整合缓存}

Spring Boot 针对不同的缓存技术实现了不同的封装，本篇主要介绍 EhCache 和 Redis 缓存。

Spring Boot 提供了以下几个注解实现声明式缓存：

| 注解 | 说明 | |----------------|-------------------------------------------| | @EnableCaching | 开启缓存功能，放在配置类或启动类上 | | @CacheConfig | 缓存配置，设置缓存名称 | | @Cacheable | 执行方法前先查询缓存是否有数据。有则直接返回缓存数据；否则查询数据再将数据放入缓存 | | @CachePut | 执行新增或更新方法后，将数据放入缓存中 | | @CacheEvict | 清除缓存 | | @Caching | 将多个缓存操作重新组合到一个方法中 |

2.1 EhCache 缓存 {#2.1--EhCache-缓存}

2.1.1 添加依赖 {#2.1.1-添加依赖}

|---------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 | <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-cache</artifactId> </dependency> <dependency> <groupId>net.sf.ehcache</groupId> <artifactId>ehcache</artifactId> </dependency> |

2.1.2 添加配置 {#2.1.2-添加配置}

1）在 src/main/resources 目录下创建 ehcache.xml 文件，内容如下：

|------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | <?xml version="1.0" encoding="UTF-8"?> <ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd">  <diskStore path="java.io.tmpdir/ehcache"/>  <defaultCache maxEntriesLocalHeap="10000" eternal="false" timeToIdleSeconds="120" timeToLiveSeconds="120" maxEntriesLocalDisk="10000000" diskExpiryThreadIntervalSeconds="120" memoryStoreEvictionPolicy="LRU"> <persistence strategy="localTempSwap"/> </defaultCache>  <cache name="department" maxElementsInMemory="1000" eternal="false" timeToIdleSeconds="50" timeToLiveSeconds="50" overflowToDisk="false" memoryStoreEvictionPolicy="LRU"/> </ehcache> |

说明：

|------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 | name：Cache 的唯一标识 maxElementsInMemory：内存中允许存储的最大的元素个数 maxElementsOnDisk：硬盘最大缓存个数，0代表无限个 clearOnFlush：内存数量最大时是否清除 eternal：缓存对象是否永久有效，如果是，超时设置将被忽略 overflowToDisk：内存不足（超过 maxElementsInMemory）时，是否启用磁盘缓存 timeToIdleSeconds：设置对象在失效前的允许闲置时间（单位：秒）。仅当eternal=false对象不是永久有效时使用，可选属性，默认值是0，也就是可闲置时间无穷大 timeToLiveSeconds：缓存数据的生存时间（TTL），也就是一个元素从构建到消亡的最大时间间隔值，这只能在元素不是永久驻留时有效，如果该值是0就意味着元素可以停顿无穷长的时间 diskPersistent：是否将缓存数据持久化到磁盘上，如果为 true，JVM 重启数据依然存在。默认值是false diskSpoolBufferSizeMB：这个参数设置DiskStore（磁盘缓存）的缓存区大小。默认是30MB。每个Cache都应该有自己的一个缓冲区 diskExpiryThreadIntervalSeconds：磁盘失效线程运行时间间隔，默认是120秒 memoryStoreEvictionPolicy：当达到 maxElementsInMemory 限制时，Ehcache 将根据指定策略清除内存。默认为 LRU（最近最少使用），其他策略有 FIFO（先进先出），LFU（较少使用） |

2）application.properties ：

|-------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 | # 缓存类型（ehcache、redis） spring.cache.type=ehcache # ehcache 配置文件 spring.cache.ehcache.config=classpath:ehcache.xml # 打印日志，查看 sql logging.level.com.light.springboot=DEBUG |

2.1.3 编码 {#2.1.3-编码}

在持久层篇的基础上，结合 Mybatis 测试：

Service 层：

|------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 | @CacheConfig(cacheNames = "department") @Service public class DepartmentService { @Autowired private DepartmentMapper departmentMapper; @CachePut(key = "#department.id") public Department save(Department department) { System.out.println("保存 id=" + department.getId() + " 的数据"); this.departmentMapper.insert(department); return department; } @CachePut(key = "#department.id") public Department update(Department department) { System.out.println("修改 id=" + department.getId() + " 的数据"); this.departmentMapper.update(department); return department; } @Cacheable(key = "#id") public Department getDepartmentById(Integer id) { System.out.println("获取 id=" + id + " 的数据"); Department department = this.departmentMapper.getById(id); return department; } @CacheEvict(key = "#id") public void delete(Integer id) { System.out.println("删除 id=" + id + " 的数据"); this.departmentMapper.deleteById(id); } } |

控制层：

|---------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 | @Controller @RequestMapping("department") @ResponseBody public class DepartmentController { @Autowired private DepartmentService departmentService; @RequestMapping("save") public Map<String,Object> save(Department department) { this.departmentService.save(department); Map<String,Object> map = new HashMap<String,Object>(); map.put("code", "200"); map.put("msg", "保存成功"); return map; } @RequestMapping("get/{id}") public Map<String,Object> get(@PathVariable("id") Integer id) { Department department = this.departmentService.getDepartmentById(id); Map<String,Object> map = new HashMap<String,Object>(); map.put("code", "200"); map.put("msg", "获取成功"); map.put("data", department); return map; } @RequestMapping("update") public Map<String,Object> update(Department department) { this.departmentService.update(department); Map<String,Object> map = new HashMap<String,Object>(); map.put("code", "200"); map.put("msg", "修改成功"); return map; } @RequestMapping("delete/{id}") public Map<String,Object> delete(@PathVariable("id") Integer id) { this.departmentService.delete(id); Map<String,Object> map = new HashMap<String,Object>(); map.put("code", "200"); map.put("msg", "删除成功"); return map; } } |

启动类：

添加 @EnableCaching 注解，开启缓存功能。

|-------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 | @EnableCaching @SpringBootApplication public class SpringbootNosqlApplication { public static void main(String[] args) { SpringApplication.run(SpringbootNosqlApplication.class, args); } } |

2.1.4 测试说明 {#2.1.4-测试说明}

由于 ehcache 缓存是存储在应用的内存中，如果使用 junit 测试，方法执行完毕缓存就释放了，无法正常测试缓存效果，因此测试使用发起 http 请求的形式。

发起保存请求：

|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 | 保存 id=2 的数据 2017-12-06 14:50:48.800 DEBUG 680 --- [nio-8081-exec-7] c.l.s.dao.DepartmentMapper.insert : ==> Preparing: insert into department(id,name,descr) values(?,?,?) 2017-12-06 14:50:48.801 DEBUG 680 --- [nio-8081-exec-7] c.l.s.dao.DepartmentMapper.insert : ==> Parameters: 2(Integer), Ehcache 部门(String), Ehcache(String) 2017-12-06 14:50:48.868 DEBUG 680 --- [nio-8081-exec-7] c.l.s.dao.DepartmentMapper.insert : <== Updates: 1 |

保存成功后，立刻发起查询请求，没有日志打印，但返回对象数据，说明数据是从缓存中获取。
发起修改请求：

|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 | 修改 id=2 的数据 2017-12-06 14:51:16.588 DEBUG 680 --- [nio-8081-exec-8] c.l.s.dao.DepartmentMapper.update : ==> Preparing: update department set name = ? , descr = ? where id = ? 2017-12-06 14:51:16.589 DEBUG 680 --- [nio-8081-exec-8] c.l.s.dao.DepartmentMapper.update : ==> Parameters: Ehcache 部门2(String), Ehcache2(String), 2(Integer) 2017-12-06 14:51:16.657 DEBUG 680 --- [nio-8081-exec-8] c.l.s.dao.DepartmentMapper.update : <== Updates: 1 |

修改成功后，立刻发起查询请求，没有日志打印，但返回修改后的对象数据，说明缓存中的数据已经同步。
发起删除请求：

|-----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 | 删除 id=2 的数据 2017-12-06 14:52:07.572 DEBUG 680 --- [nio-8081-exec-1] c.l.s.dao.DepartmentMapper.deleteById : ==> Preparing: delete from department where id = ? 2017-12-06 14:52:07.572 DEBUG 680 --- [nio-8081-exec-1] c.l.s.dao.DepartmentMapper.deleteById : ==> Parameters: 2(Integer) 2017-12-06 14:52:07.613 DEBUG 680 --- [nio-8081-exec-1] c.l.s.dao.DepartmentMapper.deleteById : <== Updates: 1 |

删除成功后，立刻发起查询请求，控制台打印 sql 语句，说明缓存数据被删除，需要查询数据库。

|-----------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 | 获取 id=2 的数据 2017-12-06 14:52:40.324 DEBUG 680 --- [nio-8081-exec-3] c.l.s.dao.DepartmentMapper.getById : ==> Preparing: select id,name,descr from department where id = ? 2017-12-06 14:52:40.325 DEBUG 680 --- [nio-8081-exec-3] c.l.s.dao.DepartmentMapper.getById : ==> Parameters: 2(Integer) 2017-12-06 14:52:40.328 DEBUG 680 --- [nio-8081-exec-3] c.l.s.dao.DepartmentMapper.getById : <== Total: 0 |

2.2 Redis 缓存 {#2.2-Redis-缓存}

2.2.1 添加依赖 {#2.2.1-添加依赖}

|-----------------|----------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 | <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId> </dependency> |

2.2.2 添加配置 {#2.2.2-添加配置}

application.properties ：

注意：spring.cache.type=redis，缓存类型设置成 redis。

完成上边 2 个步骤后，其他步骤与测试 Ehcache 时的步骤一致。

测试结果也一致，此处省略。

三、整合 Redis {#三、整合-Redis}

上一个小节其实已经介绍了 Spring Boot 整合 Redis 的内容。

在添加 redis 依赖包启动项目后，Spring Boot 会自动配置 RedisCacheManger 和 RedisTemplate 的 Bean。如果开发者不想使用 Spring Boot 写好的 Redis 缓存，而是想使用其 API 自己实现缓存功能、消息队列或分布式锁之类的需求时，可以继续往下浏览。

Spring Data Redis 为我们提供 RedisTemplate 和 StringRedisTemplate 两个模板进行数据操作，它们主要的访问方法如下：

| 方法 | 说明 | |---------------|---------------| | opsForValue() | 操作简单属性的数据 | | opsForList() | 操作含有 list 的数据 | | opsForSet() | 操作含有 set 的数据 | | opsForZSet() | 操作含有 zset 的数据 | | opsForHash() | 操作含有 hash 的数据 |

3.1 添加依赖 {#3.1-添加依赖}

|-----------------|----------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 | <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId> </dependency> |

3.2 配置连接 {#3.2-配置连接}

|---------------|----------------------------------------------------------------------------------------------| | 1 2 3 | spring.redis.host=192.168.2.11 spring.redis.port=6379 spring.redis.password=redis123 |

3.3 编码 {#3.3-编码}

|------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | @Component public class RedisDao { @Autowired private StringRedisTemplate stringRedisTemplate; public void set(String key, String value) { this.stringRedisTemplate.opsForValue().set(key, value); } public String get(String key) { return this.stringRedisTemplate.opsForValue().get(key); } public void delete(String key) { this.stringRedisTemplate.delete(key); } } |

3.4 测试 {#3.4-测试}

测试结果省略...

四、整合 MongoDB {#四、整合-MongoDB}

Spring Data MongoDB 提供了 MongoTemplate 模板和 Repository 让开发者进行数据访问。

4.1 添加依赖 {#4.1-添加依赖}

|-----------------|------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 | <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-mongodb</artifactId> </dependency> |

4.2 配置连接 {#4.2-配置连接}

|---------------|----------------------------------------------------------------------------------------------------------------| | 1 2 3 | spring.data.mongodb.host=192.168.2.31 spring.data.mongodb.port=27017 spring.data.mongodb.database=test |

4.3 编码 {#4.3-编码}

4.3.1 使用 MongoTemplate {#4.3.1-使用-MongoTemplate}

|------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 | @Component public class MongodbDao { @Autowired private MongoTemplate mongoTemplate; public void insert(Department department) { this.mongoTemplate.insert(department); } public void deleteById(int id) { Criteria criteria = Criteria.where("id").is(id); Query query = new Query(criteria); this.mongoTemplate.remove(query, Department.class); } public void update(Department department) { Criteria criteria = Criteria.where("id").is(department.getId()); Query query = new Query(criteria); Update update = new Update(); update.set("descr", department.getDescr()); this.mongoTemplate.updateMulti(query, update, Department.class); } public Department getById(int id) { Criteria criteria = Criteria.where("id").is(id); Query query = new Query(criteria); return this.mongoTemplate.findOne(query, Department.class); } public List<Department> getAll() { List<Department> userList = this.mongoTemplate.findAll(Department.class); return userList; } } |

4.3.2 使用 Repository {#4.3.2-使用-Repository}

|-----------------|------------------------------------------------------------------------------------------------| | 1 2 3 4 | public interface DepartmentRepository extends MongoRepository<Department, Integer> { } |

测试方式与 Redis 测试大同小异，测试结果省略...