JavaEE进阶知识学习----SpringBoot高级（二）SpringBoot使用缓存
缓存使用
1.使用IDEA创建SpringBoot项目，引入cache模块，web模块，mysql模块，Mybatis模块
2.创建mysql数据库spring_cache
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;3.创建JavaBean封装数据
package com.springboot.cache.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 + "]";
}
}package com.springboot.cache.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 + "]";
}
}4.整合Mybatis
- Application.properties中配置数据源
spring.datasource.url=jdbc:mysql://localhost:3306/spring_cache
spring.datasource.username=root
spring.datasource.password=1234
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
mybatis.configuration.map-underscore-to-camel-case=true
logging.level.com.springboot.cache.mapper = debug使用注解版的Mybatis
- 使用@MapperScan指定需要扫描的Mapper接口所在的包
@MapperScan("com.springboot.cache.mapper") @SpringBootApplication public class CacheApplication { public static void main(String[] args) { SpringApplication.run(CacheApplication.class, args); } }- 编写Employee接口和DepartmentMapper接口
@Mapper 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 deleteEmpById(Integer id); @Insert("insert into employee(lastName.email,gender,d_id) values(#{lastName},#{email},#{gender},#{did})") public void insertEmployee(Employee employee); }- 编写service层代码
@Service public class EmployeeService { @Autowired private EmployeeMapper employeeMapper; public Employee getEmp(Integer id){ return employeeMapper.getEmpById(id); } }- 编写controller层代码
@RestController public class EmployeeController { @Autowired private EmployeeService employeeService; @GetMapping("/emp/{id}") public Employee getEmployee(@PathVariable("id") Integer id){ Employee emp = employeeService.getEmp(id); return emp; } }
5.开启基于注解@EnableCaching的缓存
@MapperScan("com.springboot.cache.mapper")
@SpringBootApplication
@EnableCaching
public class CacheApplication {
public static void main(String[] args) {
SpringApplication.run(CacheApplication.class, args);
}
}6.标注缓存注解即可
@Service
public class EmployeeService {
@Autowired
private EmployeeMapper employeeMapper;
/**
* 将方法结果进行缓存，以后再要相同的数据，就直接从缓存中去
* @param id
* @return
*/
@Cacheable(cacheNames = "emp" , key = "#id")
public Employee getEmp(Integer id){
return employeeMapper.getEmpById(id);
}
}注解@Cacheable说明：
将方法结果进行缓存，以后再要相同的数据，就直接从缓存中去
属性说明：
- cacheNames/value:指定缓存组件的名字，CacheManager管理多个cache组件，对缓存的真正CRUD操作在Cache中，每一个缓存都有自己唯一的一个名字
- key:缓存数据使用的key,可以使用这个属性来指定，默认是使用方法参数的值1，方法的返回值
@Cacheable(cacheNames = "emp" , key = "#id")缓存的名字是emp，key是方法中参数id的值，这种写法还有如下可以取到其他参数
| 名字 | 描述 | 示例 |
|---|---|---|
| methodName | 当前被调用的方法名 | root.methodName |
| method | 当前被调用的方法 | root.method.name |
| target | 当前被调用的目标对象 | root.target |
| targetClass | 当前被调用的目标对象类 | root.targetClass |
| args | 当前被调用的方法的参数列表 | root.args[0] |
| caches | 当前方法调用使用的缓存列表（如@Cacheable(value={“cache1”,”cache2”})），则有两个cache | root.caches[0].name |
| result | 方法执行后的返回值 | result |
- CacheManager属性：指定缓存管理器
- condition:指定符合条件的才进入缓存
java
@Cacheable(cacheNames = "emp",condition = "#id > 0")
unless：否定缓存，当unless指定的条件为true,该方法的返回值就不会被缓存，可以获取结果进行判断
// 使用unless判断结果为null就不缓存 @Cacheable(cacheNames = "emp",condition = "#id > 0",unless = "#result == null ")