（十六）SpringBoot之使用 Caching- - EhCache

一、案例

　　1.1　　引入maven依赖

<!-- caching -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-cache</artifactId>
        </dependency>
        <dependency>
            <groupId>net.sf.ehcache</groupId>
            <artifactId>ehcache</artifactId>
        </dependency>

　　1.2　　配置application.properties

#echache缓存
spring.cache.type=ehcache
spring.cache.ehcache.config=classpath:config/ehcache.xml

　　1.3　　配置config/ehcache.xml

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="ehcache.xsd">
    <cache name="roncooCache" eternal="false" maxEntriesLocalHeap="0"
        timeToIdleSeconds="50"></cache>
    <!-- eternal：true表示对象永不过期，此时会忽略timeToIdleSeconds和 timeToLiveSeconds属性，默认为false -->
    <!-- maxEntriesLocalHeap：堆内存中最大缓存对象数，0没有限制 -->

    <!-- timeToIdleSeconds： 设定允许对象处于空闲状态的最长时间，以秒为 单位。当对象自从最近一次被访问后，如果处于空闲状态的时间超过了 
        timeToIdleSeconds属性值，这个对象就会过期，EHCache将把它从缓存中清空。 只有当eternal属性为false，该属性才有效。如果该属性值为0，则表示对象可以 
        无限期地处于空闲状态 -->
</ehcache>

　　1.4　　启用@EnableCaching 注解支持

@EnableCaching
@SpringBootApplication
public class Springboot01Application {
    
    public static void main(String[] args) {
        SpringApplication.run(Springboot01Application.class, args);
    }
}

　　1.5　　编写实体类

如下代码，写完后运行Springboot01Application.java会自动在数据库生成表结构

package com.shyroke.entity;

import java.io.Serializable;
import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@Entity
@JsonIgnoreProperties({ "handler","hibernateLazyInitializer" })  
@Table(name="user")
public class UserBean  {

    @Id
    @GeneratedValue
    private Integer id;

    @Column
    private Date createTime;

    @Column
    private String userName;

    @Column
    private String userIp;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getUserIp() {
        return userIp;
    }

    public void setUserIp(String userIp) {
        this.userIp = userIp;
    }

    @Override
    public String toString() {
        return "RoncooUserLog [id=" + id + ", createTime=" + createTime + ", userName=" + userName + ", userIp=" + userIp + "]";
    }

}

　　1.6　　编写控制器

package com.shyroke.controller;

import java.util.Date;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import com.shyroke.dao.UserMapper;
import com.shyroke.entity.UserBean;
import com.shyroke.service.CacheUserService;

@Controller
@RequestMapping(value = "/")
public class IndexController {

    @Autowired
    private CacheUserService cacheUserService;

    
    @RequestMapping(value = "/select")
    @ResponseBody
    public UserBean get() {
        return cacheUserService.getUserById(1);
    }

    @RequestMapping(value = "/update")
    @ResponseBody
    public UserBean update() {
        UserBean bean = cacheUserService.getUserById(1);
        bean.setUserName("测试");
        bean.setCreateTime(new Date());
        cacheUserService.update(bean);
        return bean;
    }

    @RequestMapping(value = "/del")
    @ResponseBody
    public String del() {
        return cacheUserService.deleteById(1);
    }

}

　　1.7　　编写服务接口和实现类

package com.shyroke.service;

import com.shyroke.entity.UserBean;

public interface CacheUserService {
    /**
     * 查询
     * 
     * @param id
     * @return
     */
    public UserBean getUserById(int id);

    /**
     * 更新
     * 
     * @param user
     * @return
     */

    public UserBean update(UserBean user);

    /**
     * 删除
     * 
     * @param id
     * @return
     */

    public String deleteById(int id);
}

package com.shyroke.service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.CacheConfig;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.cache.annotation.CachePut;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;

import com.shyroke.dao.UserMapper;
import com.shyroke.entity.UserBean;
import com.shyroke.service.CacheUserService;

@CacheConfig(cacheNames = "roncooCache")
@Service
public class CacheUserServiceImpl implements CacheUserService{

    @Autowired
    private UserMapper userMapper;
    
    @Cacheable(key = "#p0")
    @Override
    public UserBean getUserById(int id) {
        System.out.println("查询功能，缓存找不到，直接读库, id=" + id);
        return userMapper.getOne(id);
    }

    @CachePut(key = "#p0")
    @Override
    public UserBean update(UserBean user) {
        System.out.println("更新功能，更新缓存，直接写库, id=" + user);
        return userMapper.save(user);
    }

    @CacheEvict(key = "#p0")
    @Override
    public String deleteById(int id) {
        System.out.println("删除功能，删除缓存，直接写库, id=" + id);
         userMapper.delete(id);
         return "删除成功";
    }

}

　　1.8　　编写userMapper.java

package com.shyroke.dao;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import com.shyroke.entity.UserBean;

public interface UserMapper extends JpaRepository<UserBean, Integer>{

}