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作者：xfk

https://www.cnblogs.com/xfk1999/p/11347793.html

一直想在springboot上集成帶緩存的redis，終于成功了。網上有1000種寫法，想找到一篇合適的還真不容易?。走下流程，加深下印象。

?環境:

springboot版本：2.1.7

orm框架：mybatis

實現?:

在serviceImpl層方法上加注解@Cacheable和@CachEvict。

@Cacheable把數據放進redis，下一次需要數據直接在緩存中取；@CacheEvict使redis中的緩存失效。

關于注解的更多詳細可以參考https://www.cnblogs.com/fashflying/p/6908028.html寫得很詳細。

準備工作：

pom.xml?：

org.springframework.bootspring-boot-starter-parent2.1.7.RELEASEorg.springframework.bootspring-boot-starter-weborg.springframework.bootspring-boot-starter-testtestjavax.servletjavax.servlet-apijavax.servletjstlorg.apache.tomcat.embedtomcat-embed-jasperorg.springframework.bootspring-boot-devtoolstruemysqlmysql-connector-java5.1.21org.mybatis.spring.bootmybatis-spring-boot-starter1.1.1org.mybatis.generatormybatis-generator-core1.3.7com.fasterxml.jackson.datatypejackson-datatype-jsr310org.springframework.bootspring-boot-starter-data-redis

application.properties文件?：

#mvcspring.mvc.view.prefix=/WEB-INF/jsp/spring.mvc.view.suffix=.jsp#mysqlspring.datasource.url=jdbc:mysql://localhost:3306/common?characterEncoding=utf-8spring.datasource.username=xfkspring.datasource.password=123456spring.datasource.driver-class-name=com.mysql.jdbc.Driver#mybatismybatis.mapper-locations=classpath:/mapper/*.xmlmybatis.type-aliases-package=com.xfk.sb.pojo#redisspring.redis.database=0spring.redis.host=127.0.0.1spring.redis.port=6379spring.redis.password=spring.redis.timeout=5000

書寫：

一，允許使用緩存：

?在springboot的主啟動類上添加注解@EnableCaching

SbApplication.java

package com.xfk.sb;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cache.annotation.EnableCaching;@SpringBootApplication@EnableCachingpublic class SbApplication {public static void main(String[] args) { SpringApplication.run(SbApplication.class, args); }}

?二，redis配置類：

?這里一個重要的點就是Serializer。RedisCache默認使用的是JdkSerializationRedisSerializer，我們要實現json格式的數據在redis上的存儲。利用Jackson2JsonRedisSerializer或GenericJackson2JsonRedisSerializer，其優點是存儲的長度小。在這里我們用GenericJackson2JsonRedisSerializer。成功之后可以換Jackson2JsonRedisSerializer試試，看一看存儲的數據有什么不同。

?cacheManager方法是用作注解@Cacheable和@CacheEvict執行service實現層方法緩存數據的，另外就是定義一個redisTemplate，哪個controller需要就在哪個controller中注入，靈活使用。

RedisConfig.java

package com.xfk.sb.config;import org.springframework.cache.annotation.CachingConfigurerSupport;import org.springframework.cache.annotation.EnableCaching;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.data.redis.cache.RedisCacheConfiguration;import org.springframework.data.redis.cache.RedisCacheManager;import org.springframework.data.redis.connection.RedisConnectionFactory;import org.springframework.data.redis.core.RedisTemplate;import org.springframework.data.redis.serializer.*;import java.time.Duration;@Configuration@EnableCachingpublic class RedisConfig extends CachingConfigurerSupport {// 過期時間private Duration timeToLive = Duration.ofHours(12);@Beanpublic RedisCacheManager cacheManager(RedisConnectionFactory connectionFactory) { RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig() .entryTtl(this.timeToLive) .serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(keySerializer())) .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(valueSerializer())) .disableCachingNullValues();return RedisCacheManager.builder(connectionFactory) .cacheDefaults(config) .transactionAware() .build(); } @Bean(name = "redisTemplate")public RedisTemplate redisTemplate(RedisConnectionFactory redisConnectionFactory) { RedisTemplate redisTemplate = new RedisTemplate<>(); redisTemplate.setConnectionFactory(redisConnectionFactory); redisTemplate.setKeySerializer(keySerializer()); redisTemplate.setHashKeySerializer(keySerializer()); redisTemplate.setValueSerializer(valueSerializer()); redisTemplate.setHashValueSerializer(valueSerializer());return redisTemplate; }private RedisSerializer keySerializer() {return new StringRedisSerializer(); }private RedisSerializer valueSerializer() {return new GenericJackson2JsonRedisSerializer(); }}

三，增刪改查Demo：

簡單的pojo類，Student.java

package com.xfk.sb.pojo;public class Student {private int id;private String name;private int age;public Student() { }public int getId() {return id; }public void setId(int id) {this.id = id; }public String getName() {return name; }public void setName(String name) {this.name = name; }public int getAge() {return age; }public void setAge(int age) {this.age = age; }@Overridepublic String toString() {return "Student{" +"id=" + id +", name='" + name + '\'' +", age=" + age +'}'; }}

?我使用的是mybatis的注解方式，簡單的幾個增刪改查方法。

xml文件，studentMapper.xml

<?xml version="1.0" encoding="UTF-8"?>/span> PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> select * from student delete from student where id = #{id} insert into student(id, name, age) values(null, #{student.name}, #{student.age}) update student set name=#{student.name}, age=#{student.age} where id = #{student.id} select * from student where id = #{id} limit 1

mapper接口，StudentMapper.java

package com.xfk.sb.mapper;import com.xfk.sb.pojo.Student;import org.apache.ibatis.annotations.Mapper;import org.apache.ibatis.annotations.Param;import org.springframework.stereotype.Component;import java.util.List;@Mapper@Componentpublic interface StudentMapper {List selectStudent();int deleteStudent(@Param("id")int id);int createStudent(@Param("student")Student student);int updateStudent(@Param("student")Student student);Student selectStudentByPrimaryKey(@Param("id")int id);}

service層接口，StudentService.java

package com.xfk.sb.service;import com.xfk.sb.pojo.Student;import java.util.List;public interface StudentService {List selectStudent();int deleteStudent(int id);int createStudent(Student student);int updateStudent(Student student);Student selectStudentByPrimaryKey(int id);}

service實現層，StudentServiceImpl.java

package com.xfk.sb.service.implement;import com.xfk.sb.mapper.StudentMapper;import com.xfk.sb.pojo.Student;import com.xfk.sb.service.StudentService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.cache.annotation.CacheConfig;import org.springframework.cache.annotation.CacheEvict;import org.springframework.cache.annotation.Cacheable;import org.springframework.cache.annotation.Caching;import org.springframework.stereotype.Service;import java.util.List;@Service@CacheConfig(cacheNames="students")public class StudentServiceImpl implements StudentService {private final StudentMapper studentMapper;@Autowiredpublic StudentServiceImpl(StudentMapper studentMapper) {this.studentMapper = studentMapper; }@Cacheable(key="'students'")@Overridepublic List selectStudent() { System.out.println("從數據庫中取selectStudent");return studentMapper.selectStudent(); }@Override@Caching(evict={ @CacheEvict(key="'singleStudent'+#id"),@CacheEvict(key="'students'"), })public int deleteStudent(int id) { System.out.println("從數據庫中刪除deleteStudent");return studentMapper.deleteStudent(id); }@Override@Caching(evict={ @CacheEvict(key="'singleStudent'+#student.id"),@CacheEvict(key="'students'"), })public int createStudent(Student student) { System.out.println("從數據庫中創建createStudent");return studentMapper.createStudent(student); }@Caching(evict={ @CacheEvict(key="'singleStudent'+#student.id"),@CacheEvict(key="'students'"), })@Overridepublic int updateStudent(Student student) { System.out.println("從數據庫中更新updateStudent");return studentMapper.updateStudent(student); }@Cacheable(key="'singleStudent'+#p0")@Overridepublic Student selectStudentByPrimaryKey(int id) { System.out.println("從數據庫中取一個selectStudentByPrimaryKey");return studentMapper.selectStudentByPrimaryKey(id); }}

?使用@CacheConfig注解，相當于在redis數據庫下建一個文件夾，以cacheNames作為文件夾的名字，統一管理這個實現層緩存的數據。正如在Redis Desktop Manager下看到的目錄結構，db0下有一個students文件夾。

?使用@Cacheable注解使緩存生效，以實現層的selectStudentByPrimaryKey()方法為例，從數據庫中根據id查詢一個Student對象。

使用@Cacheable(key="'singleStudent'+#p0")，#p0就是形參parameter0，多個參數就是#p1，#p2，，，也可以寫成#id，注意singleStudent字符串一定要用單引號擴上，然后使用字符串的拼接模式，這個變量的規則是spring的EL表達式，一定要用加上#符號，如果是一個對象則可以直接用"."引用屬性，參考createStudent()方法中的#student.id 。

屬性key相當于在students文件夾下的文件夾創建一條以singleStudent+#p0為名字的一條緩存數據，在Redis Desktop Manager可以看到，由于students文件夾下的文件夾沒有名字，所以成功緩存數據的命名是students::singleStudent1，兩個引號之間為空。這就相當以這個命名空間下的唯一key，可以根據唯一key準確的失效緩存數據。

?@CacheEvict注解使緩存失效，根據需求要保證數據庫與緩存的一致性，所以操作數據庫之后要同步緩存。

在更新，刪除和增加后要使緩存失效，不能返回過時的信息。在這里使用@Caching的目的是使多條緩存失效，它集合了@Cacheable，@CacheEvict，@CachePut，可以很直觀的管理生效與失效。還可以直接使用@CacheEvict(allEntries=true)使這個命名空間下的所有緩存失效。

到這里核心工作完成得差不多了，就還差controller返回視圖層了。

controller層，StudentController.java

package com.xfk.sb.web;import com.xfk.sb.pojo.Student;import com.xfk.sb.service.StudentService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.data.redis.core.StringRedisTemplate;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.*;import java.util.List;@Controllerpublic class StudentController {private final StudentService studentService;private final StringRedisTemplate redis;@Autowiredpublic StudentController(StudentService studentService, StringRedisTemplate redis) {this.studentService = studentService;this.redis = redis; }@GetMapping("/students")public String listStudent(Model model){ List students = studentService.selectStudent(); model.addAttribute("students", students);return "listStudent"; }@DeleteMapping("/students/{id}")public String deleteStudent(@PathVariable("id")int id) throws Exception{ studentService.deleteStudent(id);return "redirect:/students"; }@PutMapping("/students")public String updateStudent(Student student){ studentService.updateStudent(student);return "redirect:/students"; }@PostMapping("/students")public String createStudent(Student student){ studentService.createStudent(student);return "redirect:/students"; }@GetMapping("/students/{id}")public String editStudent(@PathVariable("id")int id, Model model){ Student s = studentService.selectStudentByPrimaryKey(id); model.addAttribute("student", s);return "editStudent"; }@RequestMapping("/test")public String test(Model model){ List students = studentService.selectStudent(); model.addAttribute("students", students);return "test"; }@RequestMapping("/getOne")public String getOne(Model model){　　　　　　 // 獲取id為1的Student對象到test.jsp Student student = studentService.selectStudentByPrimaryKey(1); model.addAttribute("student", student);return "test"; }}

?使用的restful風格，返回的jsp頁面，/test和/getOne用來驗證緩存是否生效。

小貼一下jsp：

listStudent.jsp

students 增加: name:?idnameage編輯刪除${each.id}${each.name}${each.age}修改刪除驗證你的jquer是否生效 $(function(){ $(".deleteStudent").click(function(){var href = $(this).attr("value"); alert(href); $("#deleteType").attr("action", href).submit(); }) $(".hhh").click(function(){ alert("你的jquer已生效"); }) })

editStudent.jsp

editStudent name: age :返回主頁

test.jsp

test${each.id}, ${each.name}, ${each.age}得到一個Student${student.id}, ${student.name}, ${student.age}

?

四，驗證測試：

?步驟：

1，/getOne

由于StudentServiceImpl.java中的System.out.println("從數據庫中取一個selectStudentByPrimaryKey");?查看后臺控制臺，可以知道這條數據是從數據庫中獲取的。

/getOne獲取的Student的id為1，所以會在Redis Desktop Manager中看到一條singleStudent1的緩存記錄。

http://localhost:8080/getOne

2，更改Redis Desktop Manager中的記錄

?比如redis庫中原來的數據是

?更改數據，因為這里改的數據是redis的，mysql里的數據還是沒變，這樣就知道了是從緩存中讀取的數據

?點擊save之后，刷新http://localhost:8080/getOne

?成功！????? 然后@CacheEvict是一樣的邏輯，指定失效的key就好了

在看不好意思，那就點個贊吧

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