Spring Boot设置并使用缓存的步骤

几个缓存注解的作用：

@cacheable：将方法的返回结果根据key指定的键保存在缓存中，以后要获取相同的数据直接从缓存*获取

• cachenames/value：指定cache组件名称
• key：指定缓存时使用的key，默认使用方法参数值，可以使用#a0、#p0、#参数名等，支持spel表达式，root可省略
• keygenerator：指定key的生成器的组件id，如自定义的keygenerator
• cachemanager：指定缓存管理器
• cacheresolver：指定缓存解析器
• condition：指定在哪种条件下缓存，如condition = “#id>=1”在参数>=1时缓存
• unless：指定该条件为真时不缓存
• sync：指定是否使用异步模式

@cacheput：不管缓存中是否有需要的数据，都会执行该注解标注的方法，并将结果更新到缓存，属性见上

@cacheevit：执行方法后，清除key指定的缓存

• allentries：默认为false，值为true，删除所有缓存
• beforeinvocation：默认为false，值为true，在方法调用之前清除缓存

@cacheconfig：定义一些通用或公共的规则，如cachenames、keygenerator等

可使用的spel表达式：

使用缓存的步骤：

（1）创建一个spring boot应用，勾选cache、web、mysql、mybatis模块,在主程序类上添加注解，开启基于注解的缓存

@mapperscan(basepackages = "com.youngpain.cache.mapper")
@springbootapplication
@enablecaching

（2）创建javabean，和数据库中的表对应，并配置数据源

spring:
 datasource:
  url: jdbc:mysql://localhost:3306/mybatis_database
  username: root
  password: 1741248769
  driver-class-name: com.mysql.jdbc.driver
 redis:
  host: 39.108.114.57
#开启驼峰命名法
mybatis:
 configuration:
  map-underscore-to-camel-case: true
logging:
 level:
  com.youngpain.cache.mapper: debug

（3）创建mapper接口进行增删改查操作

/**
 * 部门表的增删改查操作
 */
public interface departmentmapper {
  @insert("insert into department(id,depart_name,depart_build) values(#{id},#{depart_name},#{depart_build})")
  void insertdepartment(department department);
  @delete("delete from department where id=#{id}")
  void deletedepartment(integer id);
  @update("update department set depart_name=#{departname},depart_build=#{departbuild} where id=#{id}")
  void updatedepartment(department department);
  @select("select * from department where id=#{id}")
  department getdepartmentbyid(integer id);
}

（4）创建service

@service
@cacheconfig(cachenames = {"departs"})
public class departmentservice {
  @autowired
  departmentmapper departmentmapper;
  @cacheable(key = "#a0.id")
  public void insertdepartment(department department) {
    departmentmapper.insertdepartment(department);
  }
  @cacheevict(key = "#p0")
  public void deletedepartment(integer id) {
    departmentmapper.deletedepartment(id);
  }
  @cacheput(key = "#a0.id")
  public department updatedepartment(department department) {
    departmentmapper.updatedepartment(department);
    return department;
  }
  @cacheable(key = "#id", condition = "#p0>=1")
  public department getdepartmentbyid(integer id) {
    return departmentmapper.getdepartmentbyid(id);
  }
}

（5）创建controller

@controller
public class departmentcontroller {
  @autowired
  departmentservice departmentservice;
  @getmapping("/index")
  public string index() {
    return "index";
  }
  @getmapping("/deletedepart/{id}")
  public string deletedepart(@pathvariable("id") integer id, model model) {
    model.addattribute("condition", "delete");
    department delete = departmentservice.getdepartmentbyid(id);
    model.addattribute("department", delete);
    departmentservice.deletedepartment(id);
    return "success";
  }
  @postmapping("/updatedepart")
  public string updatedepart(department department, model model) {
    model.addattribute("condition", "update");
    department update = departmentservice.updatedepartment(department);
    model.addattribute("department", update);
    return "success";
  }
  @getmapping("/getdepart/{id}")
  public string getdepartmentbyid(@pathvariable("id") integer id, model model) {
    model.addattribute("condition", "delete");
    department get = departmentservice.getdepartmentbyid(id);
    model.addattribute("department", get);
    return "success";
  }
}

（6）测试结果：

@cacheable：第一次查询数据，控制台发出sql语句，之后再查询直接从缓存中获取
@cacheput：调用方法修改某个数据后，再次查询该数据是从缓存中获取的更新后的数据
@cacheevict：调用该方法后，再次查询某个数据需要重新发出sql语句查询

ps：之前只是用markdown记笔记，今天第一次用markdown写文章，写起来好舒服啊qaq

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