高并发下Redis会出现的问题:
- 缓存穿透
- 缓存雪崩
- 热点缓存
一、定义commons工程11-dubboCommons
(1) 创建工程
创建Maven的Java工程,并命名为11-dubboCommons
(2) 定义pom文件
<groupId>com.abc</groupId>
<artifactId>11-dubboCommons</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.4</version>
<scope>provided</scope>
</dependency>
</dependencies>
(3) 定义实体类
(4) 定义业务接口
(5) 将工程安装到本地库
运行Maven的install命令,将工程安装到本地版本库,以备其它工程使用
二、定义提供者11-provider-springboot
(1) 创建工程
创建一个Spring Boot工程,并重命名为11-provider-springboot
(2) 定义pom文件
A、添加dubbo与spring boot整合依赖
B、添加zkClient依赖
C、其它依赖
- dubboCommons依赖
- spring boot与redis整合依赖
- mybatis与spring boot整合依赖
- 数据源Druid依赖
- mysql驱动依赖
- slf4j-log4j12依赖
- spring-boot-starter-web依赖
<groupId>com.abc</groupId>
<artifactId>11-provider-springboot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.5.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<!--dubbo与spring boot整合依赖-->
<dependency>
<groupId>com.alibaba.spring.boot</groupId>
<artifactId>dubbo-spring-boot-starter</artifactId>
<version>2.0.0</version>
</dependency>
<!-- zk客户端依赖:zkclient -->
<dependency>
<groupId>com.101tec</groupId>
<artifactId>zkclient</artifactId>
<version>0.10</version>
</dependency>
<dependency>
<groupId>com.abc</groupId>
<artifactId>11-dubboCommons</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<!--Spring Boot与Redis整合依赖-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!--mybatis与Spring Boot整合依赖-->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>
<!--数据源Druid依赖-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.10</version>
</dependency>
<!--MySQL驱动依赖-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.25</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
<resources>
<!--注册dao包下mybatis映射文件为资源目录-->
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
</resources>
</build>
(3) 定义Service实现类
import com.abc.bean.Employee;
import com.abc.dao.EmployeeDao;
import com.alibaba.dubbo.config.annotation.Service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.data.redis.core.BoundValueOperations;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;
import java.util.concurrent.TimeUnit;
@Service // Dubbo的注解 <dubbo:service/>
@Component
public class EmployeeServiceImpl implements EmployeeService {
@Autowired
private EmployeeDao dao;
@Autowired
private RedisTemplate<Object, Object> redisTemplate;
// 当有对象插入时会清空realTimeCache缓存空间
@CacheEvict(value="realTimeCache", allEntries = true)
@Transactional(rollbackFor = Exception.class)
@Override
public void addEmployee(Employee employee) {
dao.insertEmployee(employee);
}
// 一旦有了查询结果,则会将此结果写入到realTimeCache缓存
// key是employee_加上方法参数
@Cacheable(value = {"realTimeCache"}, key = "'employee_'+#id")
@Override
public Employee findEmployeeById(int id) {
// 从DB查询
System.out.println("从DB查询id = " + id);
return dao.selectEmployeeById(id);
}
private volatile Object count;
// 双重检测锁机制解决Reids的热点缓存问题
@Override
public Integer findEmployeeCount() {
// 获取Redis操作对象
BoundValueOperations<Object, Object> ops = redisTemplate.boundValueOps("count");
// 从缓存获取数据
count = ops.get();
if(count == null) {
synchronized (this) {
count = ops.get();
if(count == null) {
System.out.println("从DB中查询");
// 从DB中查询
count = dao.selectEmployeeCount();
// 将查询结果存放到Redis
ops.set(count, 10, TimeUnit.SECONDS);
}
}
}
return (Integer) count;
}
}
(4) 定义Dao接口
(5) 定义映射文件
(6) 修改启动类
在启动类上必须要添加@EnableDubboConfiguration注解,开启Dubbo的自动配置功能
(7) 修改主配置文件
server:
port: 8888
mybatis:
# 注册mybatis中实体类的别名
type-aliases-package: com.abc.bean
# 注册映射文件
mapper-locations: classpath:com/abc/dao/*.xml
spring:
# 注册数据源
datasource:
# 指定数据源类型为Druid
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql:///test?useUnicode=true&characterEncoding=utf8
username: root
password: root
# 连接Redis服务器
redis:
host: 39.97.176.160
port: 6379
# 连接Redis高可有集群
# redis:
# sentinel:
# master: mymaster
# nodes:
# - sentinelOS1:26379
# - sentinelOS2:26379
# - sentinelOS3:26379
# 配置缓存
cache:
type: redis # 指定缓存类型
cache-names: realTimeCache # 指定缓存区域名称
# 功能等价于spring-boot配置文件中的<dubbo:application/>
application:
name: 11-provider-springboot
# 指定zk注册中心
dubbo:
registry: zookeeper://39.97.176.160:2181
# zk集群作注册中心
# registry: zookeeper://zkOS1:2181?backup=zkOS2:2181,zkOS3:2181
三、定义消费者11-consumer-springboot
(1) 创建工程
创建一个Spring Boot工程,并重命名为11-consumer-springboot
(2) 定义pom文件
- dubbo与spring boot整合依赖
- zkClient依赖
- dubboCommons依赖
- JSP引擎jasper依赖
- slf4j-log4j12依赖
- spring-boot-starter-web依赖
(3) 修改主配置文件
spring:
# 功能等价于spring-dubbo配置文件中的<dubbo:application/>
application:
name: 11-consumer-springboot
# 指定zk注册中心
dubbo:
registry: zookeeper://39.97.176.160:2181
# zk集群作注册中心
# registry: zookeeper://zkOS1:2181?backup=zkOS2:2181,zkOS3:2181
(4) 创建index.jsp页面
在src/main/webapp目录下定义index.jsp文件
(5) 定义处理器
package com.abc.controller;
import com.abc.bean.Employee;
import com.abc.service.EmployeeService;
import com.alibaba.dubbo.config.annotation.Reference;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
@RequestMapping("/consumer/employee")
public class SomeController {
// @Autowired
@Reference // Dubbo的注解 <dubbo:reference />
private EmployeeService employeeService;
@PostMapping("/register")
public String someHandle(Employee employee, Model model) {
employeeService.addEmployee(employee);
model.addAttribute("employee", employee);
return "/welcome.jsp";
}
@RequestMapping("/find/{id}")
@ResponseBody
public Employee findHandle(@PathVariable("id") int id) {
return employeeService.findEmployeeById(id);
}
@RequestMapping("/count")
@ResponseBody
public Integer countHandle() {
return employeeService.findEmployeeCount();
}
}
(6) 定义welcome.jsp页面
(7) 修改入口类
四、测试
当有对象插入时会清空realTimeCache缓存空间
一旦有了查询结果,则会将此结果写入到realTimeCache缓存
http://localhost:8080/index.jsp 首页
http://localhost:8080//consumer/employee/find/2 根据Id查找
http://localhost:8080//consumer/employee/count 查找总数