SpringBoot整合Cache缓存深入理解

我们在上一篇的基础上继续学习。

SpringBoot整合cache缓存入门

一、@Caching注解

@Caching注解用于在方法或者类上，同时指定多个Cache相关的注解。

示例代码如下:

import com.example.myspringboot.bean.Student;
import com.example.myspringboot.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.cache.annotation.Caching;
import org.springframework.stereotype.Service;

import java.util.Optional;

/**
 * @author qx
 * @date 2023/06/20
 * @desc 服务层
 */
@Service
public class StudentService {

    @Autowired
    private StudentRepository studentRepository;

    @Cacheable(value = "student", key = "#id")
    public Student getStudent(Long id) {
        return studentRepository.findById(id).orElse(null);
    }

   @Caching(cacheable = {@Cacheable(value = "student", key = "#student.id")}, put = {@CachePut(value = "student", key = "#student.id")})
    public Student saveStudent(Student student) {
        studentRepository.save(student);
        return student;
    }
}

在saveStudent方法中，@Caching注解中使用了cacheable属性和put属性，该方法先是使用@Cacheable注解查询缓存缓存，然后再使用@CachePut注解把缓存存储到指定的key中。

控制层代码:

import com.example.myspringboot.bean.Student;
import com.example.myspringboot.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;


/**
 * @author qx
 * @date 2023/06/19
 * @desc
 */
@RestController
@RequestMapping("/student")
public class StudentController {

    @Autowired
    private StudentService studentService;

    @GetMapping("/{id}")
    public Student getStudent(@PathVariable Long id) {
        return studentService.getStudent(id);
    }

    @GetMapping("/save")
    public Student updateStudent(Student student) {
        return studentService.saveStudent(student);
    }
}

测试:

Hibernate: select student0_.id as id1_0_0_, student0_.age as age2_0_0_, student0_.name as name3_0_0_ from t_student student0_ where student0_.id=?
Hibernate: update t_student set age=?, name=? where id=?

我们调用新增的方法，先是清除了缓存然后再添加到缓存。

我们再次请求查询数据接口发现控制台没有执行sql语句

二、@CacheConfig注解

@CacheConfig注解可以把一些缓存配置提取到类级别的一个地方，这样我们就不必在每个方法都设置相关的配置。

我们之前设置缓存可以使用如下代码:

import com.example.myspringboot.bean.Student;
import com.example.myspringboot.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.*;
import org.springframework.stereotype.Service;


/**
 * @author qx
 * @date 2023/06/19
 * @desc 服务层
 */
@Service
public class StudentService {

    @Autowired
    private StudentRepository studentRepository;

    @Cacheable(value = "student", key = "#id")
    public Student getStudent(Long id) {
        return studentRepository.findById(id).orElse(null);
    }

    @CachePut(value = "student", key = "#student.id")
    public Student saveStudent(Student student) {
        studentRepository.save(student);
        return student;
    }

    /**
     * 清除缓存
     */
    @CacheEvict(value = "student", key = "#id")
    public void deleteCache(Long id) {
        System.out.println("清除缓存");
    }
}

然后我们使用@CacheConfig配置公共的缓存变量。

import com.example.myspringboot.bean.Student;
import com.example.myspringboot.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.*;
import org.springframework.stereotype.Service;


/**
 * @author qx
 * @date 2023/06/19
 * @desc 服务层
 */
@Service
@CacheConfig(cacheNames = {"student"})
public class StudentService {

    @Autowired
    private StudentRepository studentRepository;

    @Cacheable(key = "#id")
    public Student getStudent(Long id) {
        return studentRepository.findById(id).orElse(null);
    }

    @CachePut(key = "#student.id")
    public Student saveStudent(Student student) {
        studentRepository.save(student);
        return student;
    }

    /**
     * 清除缓存
     */
    @CacheEvict(key = "#id")
    public void deleteCache(Long id) {
        System.out.println("清除缓存");
    }
}

测试后发现效果是一样的。

三、condition&unless属性

condition：指定缓存的条件，满足什么条件才缓存。

unless: 否定缓存，当满足unless条件时，方法的结果不就行缓存。

// ID大于0才会进行缓存 
@Cacheable(key = "#id", condition = "#id>0")
    public Student getStudent(Long id) {
        return studentRepository.findById(id).orElse(null);
    }

四、allEntries&beforeInvocation属性

这两个属性都可以清除全部缓存数据，不过allEntries是方法调用后清理，beforeInvocation是方法调用前清理。

import com.example.myspringboot.bean.Student;
import com.example.myspringboot.repository.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.*;
import org.springframework.stereotype.Service;

/**
 * @author qx
 * @date 2023/06/19
 * @desc 服务层
 */
@Service
@CacheConfig(cacheNames = {"student"})
public class StudentService {

    @Autowired
    private StudentRepository studentRepository;

    @Cacheable(key = "#id", condition = "#id>0")
    public Student getStudent(Long id) {
        return studentRepository.findById(id).orElse(null);
    }

    @CachePut(key = "#student.id")
    public Student saveStudent(Student student) {
        studentRepository.save(student);
        return student;
    }

    /**
     * 清除所有缓存
     */
    @CacheEvict(allEntries = true)
    public void deleteCache() {
        System.out.println("清除缓存");
    }
}

清除所有缓存并查询两个数据并缓存

清除缓存
Hibernate: select student0_.id as id1_0_0_, student0_.age as age2_0_0_, student0_.name as name3_0_0_ from t_student student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_0_, student0_.age as age2_0_0_, student0_.name as name3_0_0_ from t_student student0_ where student0_.id=?

重新重新数据发现重新执行了sql语句

清除缓存
Hibernate: select student0_.id as id1_0_0_, student0_.age as age2_0_0_, student0_.name as name3_0_0_ from t_student student0_ where student0_.id=?
Hibernate: select student0_.id as id1_0_0_, student0_.age as age2_0_0_, student0_.name as name3_0_0_ from t_student student0_ where student0_.id=?
清除缓存
Hibernate: select student0_.id as id1_0_0_, student0_.age as age2_0_0_, student0_.name as name3_0_0_ from t_student student0_ where student0_.id=?

五、集成Redis实现缓存

1.添加依赖

 <!--redis-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

2.配置Redis做为缓存管理器

#设置缓存类型，这里使用Redis作为缓存服务器
spring.cache.type=redis