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我们知道内存的读取速度远大于硬盘的读取速度，当需要重复的获取相同数据时，一次一次的请求数据库或者远程服务，导致在数据库查询或者远程方法调用上小号大量的时间，最终导致程序性能降低，这就是数据缓存要解决的问题(学过计算机组成原理或者操作系统的同学们应该比较熟悉)
一、Spring缓存支持
Spring框架定义了org.springframework.cache CacheManager和org.springframework.cache.Cache接口来统一不同的缓存技术
CacheManager常用方法如下
1：@Cacheable
该注解可以标记在一个方法上，也可以标记在一个类上，当标记在一个方法上时表示该方法是支持缓存的，当标记在一个类上时则表示该类所有的方法都是支持缓存的。对于一个支持缓存的方法，在方法执行前，Spring先检查缓存中是否存在方法返回的数据，如果存在则直接返回缓存数据，如果不存在，则调用方法并将方法返回值存入缓存
2：@CacheEvict
该注解用来标注在需要清楚缓存元素的方法或类上，当标记在一个类上时，表示其中所有方法的执行都会触发缓存的清除操作
3：@CachePut
该注解也可以声明一个方法支持缓存功能
4：Caching
该注解可以在一个方法或类上同时指定多个Spring Cache相关的注解
5：CacheConfig
该注解作用在类上可以设置当前缓存的一些公共设置
二、Spring Boot缓存支持
1：创建基于spring-voot-starter-cache 和spring-boot-starter-data-jpa依赖的Spring BootWeb应用
2：配置application.properties文件 代码如下
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server.servlet.context-path=/ch6_10
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###
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##数据源信息配置
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###
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#数据库地址
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spring.datasource.url=jdbc:mysql://localhost:3306/springbootjpa?characterEncoding=utf8
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#数据库用户名
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spring.datasource.username=root
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#数据库密码
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spring.datasource.password=root
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#数据库驱动
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spring.datasource.driver-class-name=com.mysql.jdbc.Driver
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####
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#JPA持久化配置
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####
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#指定数据库类型
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spring.jpa.database=MYSQL
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#指定是否在日志中显示SQL语句
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spring.jpa.show-sql=
true
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#指定自动创建、更新数据库表等配置，update表示如果数据库中存在持久化类对应的表就不创建，不存在就创建对应的表
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spring.jpa.hibernate.ddl-auto=update
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#让控制器输出的JSON字符串格式更美观
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spring.jackson.serialization.indent-output=
true
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3：修改pom.xml文件 添加mysql依赖
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<?xml version="1.0" encoding="UTF-8"?>
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-
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<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0">
-
-
<modelVersion>4.0.0
</modelVersion>
-
-
-
-
<parent>
-
-
<groupId>org.springframework.boot
</groupId>
-
-
<artifactId>spring-boot-starter-parent
</artifactId>
-
-
<version>2.1.8.RELEASE
</version>
-
-
<relativePath/>
-
-
<!-- lookup parent from repository -->
-
-
-
</parent>
-
-
<groupId>com.ch
</groupId>
-
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<artifactId>ch6_10
</artifactId>
-
-
<version>0.0.1-SNAPSHOT
</version>
-
-
<name>ch6_10
</name>
-
-
<description>Demo project for Spring Boot
</description>
-
-
-
-
<properties>
-
-
<java.version>11
</java.version>
-
-
</properties>
-
-
-
-
<dependencies>
-
-
-
-
<dependency>
-
-
<groupId>org.springframework.boot
</groupId>
-
-
<artifactId>spring-boot-starter-cache
</artifactId>
-
-
</dependency>
-
-
-
-
<dependency>
-
-
<groupId>org.springframework.boot
</groupId>
-
-
<artifactId>spring-boot-starter-data-jpa
</artifactId>
-
-
</dependency>
-
-
-
-
<dependency>
-
-
<groupId>org.springframework.boot
</groupId>
-
-
<artifactId>spring-boot-starter-web
</artifactId>
-
-
</dependency>
-
-
<!-- 添加MySQL依赖 -->
-
-
-
-
-
<dependency>
-
-
<groupId>mysql
</groupId>
-
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<artifactId>mysql-connector-java
</artifactId>
-
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<version>5.1.45
</version>
-
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<!-- MySQL8.x时，请使用8.x的连接器 -->
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-
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</dependency>
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-
-
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<dependency>
-
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<groupId>org.springframework.boot
</groupId>
-
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<artifactId>spring-boot-starter-test
</artifactId>
-
-
<scope>test
</scope>
-
-
</dependency>
-
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</dependencies>
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-
-
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<build>
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-
-
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<plugins>
-
-
-
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<plugin>
-
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<groupId>org.springframework.boot
</groupId>
-
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<artifactId>spring-boot-maven-plugin
</artifactId>
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-
</plugin>
-
-
</plugins>
-
-
</build>
-
-
</project>
4：创建持久化实体类
代码如下
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package com.
ch.
ch6_10.
entity;
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import java.
io.
Serializable;
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import javax.
persistence.
Entity;
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import javax.
persistence.
GeneratedValue;
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import javax.
persistence.
GenerationType;
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import javax.
persistence.
Id;
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import javax.
persistence.
Table;
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import com.
fasterxml.
jackson.
annotation.
JsonIgnoreProperties;
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@Entity
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@Table(name =
"student_table")
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@JsonIgnoreProperties(value = {
"hibernateLazyInitializer"})
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public
class
Student
implements
Serializable{
-
private
static final long serialVersionUID = 1L;
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@Id
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@GeneratedValue(strategy =
GenerationType.
IDENTITY)
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private int id;
//主键
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private
String sno;
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private
String sname;
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private
String ssex;
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public
Student() {
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super();
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}
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public
Student(int id,
String sno,
String sname,
String ssex) {
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super();
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this.
id = id;
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this.
sno = sno;
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this.
sname = sname;
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this.
ssex = ssex;
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}
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public int
getId(
) {
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return id;
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}
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public
void
setId(
int id) {
-
this.
id = id;
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}
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public
String
getSno(
) {
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return sno;
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}
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public
void
setSno(
String sno) {
-
this.
sno = sno;
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}
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public
String
getSname(
) {
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return sname;
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}
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public
void
setSname(
String sname) {
-
this.
sname = sname;
-
}
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public
String
getSsex(
) {
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return ssex;
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}
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public
void
setSsex(
String ssex) {
-
this.
ssex = ssex;
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}
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}
5：创建数据访问接口
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package com.ch.ch6_10.repository;
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import org.springframework.
data.jpa.repository.JpaRepository;
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import com.ch.ch6_10.entity.Student;
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public
interface
StudentRepository
extends
JpaRepository<
Student, Integer>{
-
-
}
6：创建业务层 包括一个接口和一个实现类
接口代码如下
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package com.ch.ch6_10.service;
-
import com.ch.ch6_10.entity.Student;
-
public
interface
StudentService {
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public Student
saveStudent
(Student student);
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public
void
deleteCache
(Student student);
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public Student
selectOneStudent
(Integer id);
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}
实现类代码如下
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package com.ch.ch6_10.service;
-
import org.springframework.beans.factory.
annotation.Autowired;
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import org.springframework.cache.
annotation.CacheEvict;
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import org.springframework.cache.
annotation.CachePut;
-
import org.springframework.cache.
annotation.Cacheable;
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import org.springframework.stereotype.Service;
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import com.ch.ch6_10.entity.Student;
-
import com.ch.ch6_10.repository.StudentRepository;
-
@Service
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public
class
StudentServiceImpl
implements
StudentService{
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@Autowired
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private StudentRepository studentRepository;
-
@Override
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@CachePut(value = "student", key="#student.id")
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public Student saveStudent(Student student) {
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Student s = studentRepository.save(student);
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System.
out.println(
"为key=" + student.getId() +
"数据做了缓存");
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return s;
-
}
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@Override
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@CacheEvict(value = "student", key="#student.id")
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public void deleteCache(Student student) {
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System.
out.println(
"删除了key=" + student.getId() +
"的数据缓存");
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}
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@Override
-
@Cacheable(value = "student")
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public Student selectOneStudent(Integer id) {
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Student s = studentRepository.getOne(id);
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System.
out.println(
"为key=" + id +
"数据做了缓存");
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return s;
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}
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}
7：创建控制器层
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package com.ch.ch6_10.controller;
-
import org.springframework.beans.factory.
annotation.Autowired;
-
import org.springframework.web.bind.
annotation.RequestMapping;
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import org.springframework.web.bind.
annotation.RestController;
-
import com.ch.ch6_10.entity.Student;
-
import com.ch.ch6_10.service.StudentService;
-
@RestController
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public
class
TestCacheController {
-
@Autowired
-
private StudentService studentService;
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@RequestMapping("/savePut")
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public Student save(Student student) {
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return studentService.saveStudent(student);
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}
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@RequestMapping("/selectAble")
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public Student select(Integer id) {
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return studentService.selectOneStudent(id);
-
}
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@RequestMapping("/deleteEvict")
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public String deleteCache(Student student) {
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studentService.deleteCache(student);
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return
"ok";
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}
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}
8：在主类中开启缓存支持
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package com.
ch.
ch6_10;
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import org.
springframework.
boot.
SpringApplication;
-
import org.
springframework.
boot.
autoconfigure.
SpringBootApplication;
-
import org.
springframework.
cache.
annotation.
EnableCaching;
-
@EnableCaching
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@SpringBootApplication
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public
class
Ch610Application {
-
public
static
void
main(
String[] args) {
-
SpringApplication.
run(
Ch610Application.
class, args);
-
}
-
}
转载：https://blog.csdn.net/jiebaoshayebuhui/article/details/127559239
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