Redis之sql缓存的具体使用

目录

• 1.环境搭建
• 2.redis配置
• 3.功能实现
• 4.缓存注解的使用说明

1.环境搭建

<!-- redistemplate -->
<dependency>
    <groupid>org.springframework.boot</groupid>
    <artifactid>spring-boot-starter-data-redis</artifactid>
</dependency>

spring:
  redis:
    host: 192.168.8.128
    port: 6380
    password: 1234
    database: 0
    timeout: 3000
    jedis:
      pool:
        max-wait: -1
        max-active: -1
        max-idle: 20
        min-idle: 10

2.redis配置

package com.yzm.redis01.config;

import com.fasterxml.jackson.annotation.jsonautodetect;
import com.fasterxml.jackson.annotation.jsoninclude;
import com.fasterxml.jackson.annotation.jsontypeinfo;
import com.fasterxml.jackson.annotation.propertyaccessor;
import com.fasterxml.jackson.core.jsongenerator;
import com.fasterxml.jackson.core.jsonparser;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.datatype.jsr310.javatimemodule;
import org.springframework.context.annotation.bean;
import org.springframework.context.annotation.configuration;

import java.io.ioexception;
import java.text.simpledateformat;
import java.time.localdatetime;
import java.time.format.datetimeformatter;

@configuration
public class objectmapperconfig {

    private static final string pattern = "yyyy-mm-dd hh:mm:ss";

    @bean(name = "myobjectmapper")
    public objectmapper objectmapper() {
        javatimemodule javatimemodule = new javatimemodule();
        javatimemodule.addserializer(localdatetime.class, new localdatetimeserializer());
        javatimemodule.adddeserializer(localdatetime.class, new localdatetimedeserializer());
        return new objectmapper()
                // 转换为格式化的json(控制台打印时，自动格式化规范)
                //.enable(serializationfeature.indent_output)
                // include.always  是序列化对像所有属性(默认)
                // include.non_null 只有不为null的字段才被序列化,属性为null 不序列化
                // include.non_empty 如果为null或者 空字符串和空集合都不会被序列化
                // include.non_default 属性为默认值不序列化
                .setserializationinclusion(jsoninclude.include.non_null)
                // 如果是空对象的时候,不抛异常
                .configure(serializationfeature.fail_on_empty_beans, false)
                // 反序列化的时候如果多了其他属性,不抛出异常
                .configure(deserializationfeature.fail_on_unknown_properties, false)
                // 取消时间的转化格式,默认是时间戳,可以取消,同时需要设置要表现的时间格式
                .configure(serializationfeature.write_dates_as_timestamps, false)
                .setdateformat(new simpledateformat(pattern))
                // 对localdatetime序列化跟反序列化
                .registermodule(javatimemodule)

                .setvisibility(propertyaccessor.all, jsonautodetect.visibility.any)
                // 此项必须配置，否则会报java.lang.classcastexception: java.util.linkedhashmap cannot be cast to xxx
                .enabledefaulttyping(objectmapper.defaulttyping.non_final, jsontypeinfo.as.property)
                ;
    }

    static class localdatetimeserializer extends jsonserializer<localdatetime> {
        @override
        public void serialize(localdatetime value, jsongenerator gen, serializerprovider serializers) throws ioexception {
            gen.writestring(value.format(datetimeformatter.ofpattern(pattern)));
        }
    }

    static class localdatetimedeserializer extends jsondeserializer<localdatetime> {
        @override
        public localdatetime deserialize(jsonparser p, deserializationcontext deserializationcontext) throws ioexception {
            return localdatetime.parse(p.getvalueasstring(), datetimeformatter.ofpattern(pattern));
        }
    }
}

package com.yzm.redis01.config;

import lombok.extern.slf4j.slf4j;
import org.springframework.cache.interceptor.keygenerator;
import org.springframework.cache.interceptor.simplekey;

import java.lang.reflect.method;
import java.util.arrays;
/**
 * key生成器
 */
@slf4j
public class mykeygenerator implements keygenerator {

    private static final string no_param = "[]";
    private static final string null_param = "_";

    @override
    public object generate(object target, method method, object... params) {
        stringbuilder key = new stringbuilder();
        key.append(target.getclass().getsimplename()).append(".").append(method.getname()).append(":");

        if (params.length == 0) {
            return new simplekey(key.append(no_param).tostring());
        }

        return new simplekey(key.append(arrays.tostring(params).replace("null", null_param)).tostring());
    }
}

package com.yzm.redis01.config;

import com.fasterxml.jackson.databind.objectmapper;
import org.springframework.cache.cachemanager;
import org.springframework.cache.annotation.enablecaching;
import org.springframework.context.annotation.bean;
import org.springframework.context.annotation.configuration;
import org.springframework.data.redis.cache.rediscacheconfiguration;
import org.springframework.data.redis.cache.rediscachemanager;
import org.springframework.data.redis.cache.rediscachewriter;
import org.springframework.data.redis.connection.redisconnectionfactory;
import org.springframework.data.redis.core.*;
import org.springframework.data.redis.serializer.jackson2jsonredisserializer;
import org.springframework.data.redis.serializer.redisserializationcontext;
import org.springframework.data.redis.serializer.stringredisserializer;

import javax.annotation.resource;
import java.time.duration;

@configuration
@enablecaching // 启动缓存
public class redisconfig {

    @bean(name = "mykeygenerator")
    public mykeygenerator mykeygenerator() {
        return new mykeygenerator();
    }

    @resource(name = "myobjectmapper")
    private objectmapper objectmapper;

    /**
     * 选择redis作为默认缓存工具
     */
    @bean
    public cachemanager cachemanager(redisconnectionfactory connectionfactory) {
        rediscachewriter rediscachewriter = rediscachewriter.nonlockingrediscachewriter(connectionfactory);
        rediscacheconfiguration cacheconfiguration = rediscacheconfiguration
                .defaultcacheconfig()
                // 默认缓存时间(秒)
                .entryttl(duration.ofseconds(300l))
                // 序列化key、value
                .serializekeyswith(redisserializationcontext.serializationpair.fromserializer(new stringredisserializer()))
                .serializevalueswith(redisserializationcontext.serializationpair.fromserializer(jackson2jsonredisserializer()))
                // 禁用缓存空值
                .disablecachingnullvalues();
        return new rediscachemanager(rediscachewriter, cacheconfiguration);
    }

    /**
     * redistemplate配置
     */
    @bean
    public redistemplate<string, object> redistemplate(redisconnectionfactory factory) {
        redistemplate<string, object> template = new redistemplate<>();
        // 配置连接工厂
        template.setconnectionfactory(factory);

        jackson2jsonredisserializer<object> jacksonserializer = jackson2jsonredisserializer();
        stringredisserializer stringredisserializer = new stringredisserializer();

        // 使用stringredisserializer来序列化和反序列化redis的key,value采用json序列化
        template.setkeyserializer(stringredisserializer);
        template.setvalueserializer(jacksonserializer);

        // 设置hash key 和value序列化模式
        template.sethashkeyserializer(stringredisserializer);
        template.sethashvalueserializer(jacksonserializer);

        //支持事务
        template.setenabletransactionsupport(true);
        template.afterpropertiesset();

        return template;
    }

    private jackson2jsonredisserializer<object> jackson2jsonredisserializer() {
        //使用jackson2jsonredisserializer来序列化和反序列化redis的value值（默认使用jdk的序列化方式）
        jackson2jsonredisserializer<object> jacksonserializer = new jackson2jsonredisserializer<>(object.class);
        jacksonserializer.setobjectmapper(objectmapper);
        return jacksonserializer;
    }
}

3.功能实现

新增、更新、删除、查询数据时，对缓存执行对应相同的操作

package com.yzm.redis01.entity;

import lombok.allargsconstructor;
import lombok.builder;
import lombok.data;
import lombok.noargsconstructor;
import lombok.experimental.accessors;

import java.io.serializable;
import java.time.localdatetime;
import java.util.date;

@data
@builder
@noargsconstructor
@allargsconstructor
@accessors(chain = true)
public class user implements serializable {
    private static final long serialversionuid = -2468903864827432779l;
    private integer id;
    private string username;
    private string password;
    private date createdate;
    private localdatetime updatedate;
}

package com.yzm.redis01.service;

import com.yzm.redis01.entity.user;

import java.util.list;

public interface userservice {

    user saveuser(user user);

    user updateuser(user user);

    int deleteuser(integer id);

    void deleteallcache();

    user getuserbyid(integer id);

    list<user> selectall();

    list<user> findall(object... params);
}

为了简便，数据不从数据库获取，这里是创建map存储数据实现

package com.yzm.redis01.service.impl;

import com.yzm.redis01.entity.user;
import com.yzm.redis01.service.userservice;
import lombok.extern.slf4j.slf4j;
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.service;

import java.time.localdatetime;
import java.util.*;

@slf4j
@service
@cacheconfig(cachenames = "users")
public class userserviceimpl implements userservice {


    private static final map<integer, user> usermap;

    static {
        usermap = new hashmap<>();
        usermap.put(usermap.size() + 1, user.builder()
                .id(usermap.size() + 1).username("root").password("root").createdate(new date()).updatedate(localdatetime.now()).build());
        usermap.put(usermap.size() + 1, user.builder()
                .id(usermap.size() + 1).username("admin").password("admin").createdate(new date()).updatedate(localdatetime.now()).build());
    }

    @override
    @cacheput(key = "#result.id", condition = "#result.id gt 0")
    public user saveuser(user user) {
        log.info("保存数据");
        int id = usermap.size() + 1;
        user build = user.builder()
                .id(id)
                .username(user.getusername())
                .password(user.getpassword())
                .createdate(new date())
                .updatedate(localdatetime.now())
                .build();
        usermap.put(id, build);
        return build;
    }

    @override
    @cacheput(key = "#user.id", unless = "#result eq null")
    public user updateuser(user user) {
        log.info("更新数据");
        if (usermap.containskey(user.getid())) {
            user update = usermap.get(user.getid());
            update.setusername(user.getusername())
                    .setpassword(user.getpassword())
                    .setupdatedate(localdatetime.now());
            usermap.replace(user.getid(), update);
            return update;
        }
        return null;
    }

    @override
    @cacheevict(key = "#id", condition = "#result gt 0")
    public int deleteuser(integer id) {
        log.info("删除数据");
        if (usermap.containskey(id)) {
            usermap.remove(id);
            return 1;
        }
        return 0;
    }

    @override
    @cacheevict(allentries = true)
    public void deleteallcache() {
        log.info("清空缓存");
    }

    @override
    @cacheable(key = "#id", condition = "#id gt 1")
    public user getuserbyid(integer id) {
        log.info("查询用户");
        return usermap.get(id);
    }

    @override
    @cacheable(key = "#root.methodname")
    public list<user> selectall() {
        log.info("查询所有");
        return new arraylist<>(usermap.values());
    }

    @override
    @cacheable(keygenerator = "mykeygenerator")
    public list<user> findall(object... params) {
        log.info("查询所有");
        return new arraylist<>(usermap.values());
    }

}

package com.yzm.redis01.controller;

import com.yzm.redis01.entity.user;
import com.yzm.redis01.service.userservice;
import org.springframework.web.bind.annotation.getmapping;
import org.springframework.web.bind.annotation.requestmapping;
import org.springframework.web.bind.annotation.requestparam;
import org.springframework.web.bind.annotation.restcontroller;

import java.util.list;

@restcontroller
@requestmapping("/user")
public class usercontroller {

    private final userservice userservice;

    public usercontroller(userservice userservice) {
        this.userservice = userservice;
    }

    @getmapping("/saveuser")
    public void saveuser() {
        user user = new user();
        user.setusername("yzm");
        user.setpassword("yzm");
        system.out.println(userservice.saveuser(user));
    }

    @getmapping("/updateuser")
    public void updateuser(integer id) {
        user user = new user();
        user.setid(id);
        user.setusername("yzm");
        user.setpassword("123");
        system.out.println(userservice.updateuser(user));
    }

    @getmapping("/deleteuser")
    public void deleteuser(@requestparam integer id) {
        system.out.println(userservice.deleteuser(id));
    }

    @getmapping("/deleteallcache")
    public void deleteallcache() {
        userservice.deleteallcache();
    }

    @getmapping("/getuserbyid")
    public void getuserbyid(@requestparam integer id) {
        system.out.println(userservice.getuserbyid(id));
    }

    @getmapping("/selectall")
    public void selectall() {
        list<user> users = userservice.selectall();
        users.foreach(system.out::println);
    }
}

4.缓存注解的使用说明

@cacheconfig：注解在类上，表示该类所有缓存方法使用统一指定的缓存区，也可以作用在方法上

@cacheable：注解在方法上，应用到读数据的方法上，如查找方法：调用方法之前根据条件判断是否从缓存获取相应的数据，缓存没有数据，方法执行后添加到缓存

#id 直接使用参数名
#p0 p0对应参数列表的第一个参数，以此类推
#user.id 参数是对象时，使用对象属性
#root. 可以点出很多方法
#root.methodname
#result 返回值

http://localhost:8080/user/getuserbyid?id=1

http://localhost:8080/user/getuserbyid?id=2

http://localhost:8080/user/selectall

@cacheable运行流程：在调用方法之前判断condition，如果为true，则查缓存；没有缓存就调用方法并将数据添加到缓存；condition=false就与缓存无关了

@cacheput：注解在方法上，应用到写数据的方法上，如新增/修改方法，调用方法之后根据条件判断是否添加/更新相应的数据到缓存：

http://localhost:8080/user/saveuser

condition条件为true，添加到缓存，根据id查询直接从缓存获取
http://localhost:8080/user/getuserbyid?id=3

http://localhost:8080/user/updateuser?id=3
http://localhost:8080/user/getuserbyid?id=3

条件condition=true，执行缓存操作
条件unless=false，执行缓存操作；跟condition相反

@cacheevict 注解在方法上，应用到删除数据的方法上，如删除方法，调用方法之后根据条件判断是否从缓存中移除相应的数据

http://localhost:8080/user/saveuser
http://localhost:8080/user/getuserbyid?id=3
http://localhost:8080/user/deleteuser?id=3

自定义缓存key自动生成器

@override
@cacheable(keygenerator = "mykeygenerator")
public list<user> findall(object... params) {
    log.info("查询所有");
    return new arraylist<>(usermap.values());
}

@slf4j
public class mykeygenerator implements keygenerator {

    private static final string no_param = "[]";
    private static final string null_param = "_";

    @override
    public object generate(object target, method method, object... params) {
        stringbuilder key = new stringbuilder();
        key.append(target.getclass().getsimplename()).append(".").append(method.getname()).append(":");

        if (params.length == 0) {
            return new simplekey(key.append(no_param).tostring());
        }

        return new simplekey(key.append(arrays.tostring(params).replace("null", null_param)).tostring());
    }
}

http://localhost:8080/user/findall

http://localhost:8080/user/findall?id=123

http://localhost:8080/user/findall?username=yzm

@caching
有时候我们可能组合多个cache注解使用；比如用户新增成功后，我们要添加id–>user；username—>user；email—>user的缓存；
此时就需要@caching组合多个注解标签了。

@caching(
    put = {
        @cacheput(value = "users", key = "#user.id"),
        @cacheput(value = "users", key = "#user.username"),
        @cacheput(value = "users", key = "#user.email")
    }
)
public user save(user user) {}

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原文链接：https://blog.csdn.net/qq_43654581/article/details/121677623