spinrgboot缓存之缓存抽象（缓存初步体验）

几个重要接口以及注解：

相关注解中的参数：

参数中的可用spel表达式：

首先搭建好用于测试缓存的环境：

1、新建一个springboot项目，选择web、mysql、mybatis、cache这些模块。

2、建立如下目录及文件

Department.java

package com.gong.springbootcache.bean;

public class Department {
    
    private Integer id;
    private String departmentName;
    
    
    public Department() {
        super();
        // TODO Auto-generated constructor stub
    }
    public Department(Integer id, String departmentName) {
        super();
        this.id = id;
        this.departmentName = departmentName;
    }
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getDepartmentName() {
        return departmentName;
    }
    public void setDepartmentName(String departmentName) {
        this.departmentName = departmentName;
    }
    @Override
    public String toString() {
        return "Department [id=" + id + ", departmentName=" + departmentName + "]";
    }
}

Employee.java

package com.gong.springbootcache.bean;

public class Employee {
    
    private Integer id;
    private String lastName;
    private String email;
    private Integer gender; //性别 1男  0女
    private Integer dId;
    
    
    public Employee() {
        super();
    }

    
    public Employee(Integer id, String lastName, String email, Integer gender, Integer dId) {
        super();
        this.id = id;
        this.lastName = lastName;
        this.email = email;
        this.gender = gender;
        this.dId = dId;
    }
    
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public Integer getGender() {
        return gender;
    }
    public void setGender(Integer gender) {
        this.gender = gender;
    }
    public Integer getdId() {
        return dId;
    }
    public void setdId(Integer dId) {
        this.dId = dId;
    }
    @Override
    public String toString() {
        return "Employee [id=" + id + ", lastName=" + lastName + ", email=" + email + ", gender=" + gender + ", dId="
                + dId + "]";
    }
    
    

}

EmployeeMapper.java

package com.gong.springbootcache.mapper;


import com.gong.springbootcache.bean.Employee;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

//@Mapper或者@MapperScan将接口扫描装配到容器中
public interface EmployeeMapper {

    @Select("select * from employee where id=#{id}")
    public Employee getEmpById(Integer id);

    @Update("update employee set lastName=#{lastName},email=#{email},gender=#{gender},d_id=#{dId} where id=#{id}")
    public void updateEmp(Employee employee);

    @Delete("delete from employee where id=#{id}")
    public void deleteEmp(Integer id);

    @Insert("insert into employee(lastName,email,gender,d_id) values(#{lastName},#{email},#{gender},#{dId}) ")
    public void insertEmp(Employee employee);
}

DepartmentMapper.java

package com.gong.springbootcache.mapper;

import com.gong.springbootcache.bean.Department;
import org.apache.ibatis.annotations.*;

//@Mapper
public interface DepartmentMapper {

    @Select("select * from department where id=#{id}")
    public Department getDeptById(Integer id);

    @Delete("delete from department where id=#{id}")
    public int deleteDeptById(Integer id);

    @Options(useGeneratedKeys = true,keyProperty = "id")
    @Insert("insert into department(department_name) values(#{departmentName})")
    public int insertDept(Department department);

    @Update("update department set department_name=#{departmentName} where id=#{id}")
    public int updateDept(Department department);
}

EmployeeController.java

package com.gong.springbootcache.controller;

import com.gong.springbootcache.bean.Employee;
import com.gong.springbootcache.service.EmployeeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class EmployeeController {

    @Autowired
    EmployeeService employeeService;

    @ResponseBody
    @RequestMapping("/emp/{id}")
    public Employee getEmp(@PathVariable("id") Integer id){
        Employee emp = employeeService.getEmp(id);
        return emp;
    }

}

数据库文件：spring_cache.sql

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for department
-- ----------------------------
DROP TABLE IF EXISTS `department`;
CREATE TABLE `department` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `departmentName` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Table structure for employee
-- ----------------------------
DROP TABLE IF EXISTS `employee`;
CREATE TABLE `employee` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `lastName` varchar(255) DEFAULT NULL,
  `email` varchar(255) DEFAULT NULL,
  `gender` int(2) DEFAULT NULL,
  `d_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/spring_cache
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

#开启驼峰命名法
mybatis.configuration.map-underscore-to-camel-case=true
#打印sql日志
logging.level.com.gong.springbootcache.mapper=debug

启动入口：

package com.gong.springbootcache;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;

@MapperScan("com.gong.springbootcache.mapper")
@SpringBootApplication
@EnableCaching
public class SpringbootCacheApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootCacheApplication.class, args);
    }

}

此时，我们启动服务器：发送请求（自己先往数据库中可以添点数据）

在控制台可以看到：

接下来我们就可以测试缓存了。

3、进行测试了

我们给EmployeeController.java中改成：

    //value：指定缓存的名字，每个缓存组件有一个唯一的名字。缓存组件由CacheManager进行管理。
    //key：缓存数据时用到的key，默认使用方法参数的值，1-方法返回值
    //#id也可这么表示：#root.args[0]（第一个参数）
    //keyGenerator：指定生成缓存的组件id，使用key或keyGenerator其中一个即可
    //cacheManager，cacheResolver：指定交由哪个缓存管理器，使用其中一个参数即可
    //condition：指定符合条件时才进行缓存
    //unless：当unless指定的条件为true，方法的返回值就不会被缓存
    //sync：是否使用异步模式
    @Cacheable(value = "emp")
    @ResponseBody
    @RequestMapping("/emp/{id}")
    public Employee getEmp(@PathVariable("id") Integer id){
        Employee emp = employeeService.getEmp(id);
        return emp;
    }

当我们第一次发送请求时，结果：

当我们再次发送该请求时，控制台就不会在sql调试了，因为已经存入到缓存中，不必再发送sql来查询结果。