MySQL与Redis实现二级缓存的方法介绍（代码示例）

1. 查询时先从缓存当中查询

2. 缓存当中如果没有数据再从数据库查询，并将数据保存进缓存当中

3. 如果缓存中查询到了数据直接返回，不再需要查询数据库

步骤实现

package redigo_pool

import (
 "flag"
 "github.com/garyburd/redigo/redis"
 "time"
)
var (
 Pool *redis.Pool
 RedisServer = flag.String("redisServer", ":6379", "")
 
)
func init() {
 Pool = &redis.Pool{
 MaxIdle: 3, //最大空闲链接数，表示即使没有redis链接事依然可以保持N个空闲链接，而不被清除
 MaxActive: 3, //最大激活连接数，表示同时最多有多少个链接
 IdleTimeout: 240 * time.Second,//最大空闲链接等待时间，超过此时间，空闲将被关闭
 Dial: func() (redis.Conn, error) {
 c, err := redis.Dial("tcp", *RedisServer)
 if err != nil {
 return nil, err
 }
 return c, err
 },
 TestOnBorrow: func(c redis.Conn, t time.Time) error {
 if time.Since(t) < time.Minute {
 return nil
 }
 _, err := c.Do("PING")
 return err
 },
 }
}

package main

import (
 "database/sql"
 "encoding/json"
 "fmt"
 "github.com/garyburd/redigo/redis"
 _ "github.com/go-sql-driver/mysql"
 "strconv"
 "web/redis/redigo_pool"
 _ "web/redis/redigo_pool"
)

type Person struct {
 Id int `db:"id"`
 Name string `db:"name"`
 Age int `db:"age"`
 Rmb int `db:"rmb"`
}

func main() {
 var cmd string
 for{
 fmt.Println("输入命令")
 fmt.Scan(&cmd)
 switch cmd {
 case "getall":
 getAll()
 default:
 fmt.Println("不能识别其他命令")
 }
 fmt.Println()
 }
}

func getAll() {
 //从连接池当中获取链接
 conn := redigo_pool.Pool.Get()
 //先查看redis中是否有数据
 //conn,_ :=redis.Dial("tcp","localhost:6379")
 defer conn.Close()
 values, _ := redis.Values(conn.Do("lrange", "mlist",0,-1))

 if len(values) > 0 {
 //如果有数据
 fmt.Println("从redis获取数据")
 //从redis中直接获取
 for _,key := range values{
 pid :=string(key.([]byte))
 id ,_:= strconv.Atoi(pid)
 results,_ := redis.Bytes(conn.Do("GET",id))
 var p Person
 err := json.Unmarshal(results,&p)
 if err != nil {
 fmt.Println("json 反序列化出错")
 }else {
 fmt.Printf("name = %s\n",p.Name)
 }
 }
 }else {
 fmt.Println("从mysql中获取")

 //查询数据库
 db,_ := sql.Open("mysql","root:Szt930708@tcp(localhost:3306)/mydb")
 defer db.Close()

 var persons []Person

 rows,_ := db.Query("select id,name,age,rmb from person")
 for rows.Next() {
 var id int
 var name string
 var age int
 var rmb int
 rows.Scan(&id,&name,&age,&rmb)
 per := Person{id,name,age,rmb}
 persons = append(persons,per)

 }
 //写入到redis中:将person以hash的方式写入到redis中
 for _,p := range persons{

 p_byte,_ := json.Marshal(p)
 _,err1 := conn.Do("SETNX",p.Id,p_byte)
 _,err2 := conn.Do("lpush","mlist",p.Id)
 // 设置过期时间
 conn.Do("EXPIRE",p.Id,60*5)
 if err1 != nil || err2 != nil {
 fmt.Println("写入失败")
 }else {
 fmt.Println("写入成功")
 }
 }
 conn.Do("EXPIRE","mlist",60*5)
 }
}