Redis Learning: Basic Use of Jedis

This article brings you relevant knowledge about Redis, which mainly organizes issues related to the basic use of Jedis, including basic Jedis operations, use of Jedis connection pools, etc., as follows Let's take a look, I hope it will be helpful to everyone.

Recommended learning: Redis video tutorial

1. Introduction to Jedis

Jedis = Java Redis

Redis can not only be operated using commands, but now basically mainstream languages ​​have API support, such as Java, C#, C, PHP, Node.js, Go, etc. There are some Java clients listed on the official website, including Jedis, Redisson, Jredis, JDBC-Redis, etc. Among them, Jedis and Redisson are officially recommended.

To use Jedis to operate redis, you need to import the jar package as follows:

2. Basic operations of Jedis

2.1 Commonly used APIs for Jedis objects

Note: Each method is the command name in redis, and the parameters of the method are the parameters of the command

##del(key)Delete the specified key and value##hset(key,field, value)##hget(key,field)lpush(key,values)##List type keys and elements

2.2Basic operations of Jedis

Operation steps:

Create a Jedis object, specify the server address and port number

Write to the server

set String type data, person=Zhang San

lpush adds list type data, cities=Zhuhai, Shenzhen, Guangzhou

Read the above data from the server and print the output

get gets the value of the string

lrange gets all the list elements of the list

Close the Jedis object and release the resources

Check whether there is data in the database through the client

Console output:

In database

Code:

package com.itheima.jedis;

import redis.clients.jedis.Jedis;

import java.util.List;

/**
 * 使用Jedis向redis中添加string和list，读取它们的值
 */
public class Demo1 {

    public static void main(String[] args) {
        //创建Jedis连接对象
        Jedis jedis = new Jedis("localhost", 6379);
        //添加string类型
        jedis.set("person", "张三");
        //添加list类型
        jedis.lpush("cities", "广州","上海","东莞");
        //读取string类型
        String person = jedis.get("person");
        //读取list类型
        List<String> cities = jedis.lrange("cities", 0, -1);
        //输出到控制器上
        System.out.println("person:" + person);
        System.out.println("cities:" + cities);
        //关闭连接对象
        jedis.close();
    }

}

3 .The use of Jedis connection pool

3.1The basic concept of Jedis connection pool

The creation and destruction of jedis connection resources consumes a lot of program performance, so jedis is We provide jedis connection pool technology. jedis

The connection pool initializes some connection objects and stores them in the connection pool when it is created. When using jedis to connect resources, you do not need to create jedis objects yourself

. Instead, obtain a resource from the connection pool for redis operation. After use, there is no need to destroy the jedis connection resource,

but return the resource to the connection pool for use by other requests.

3.2Jedis connection pool API

Method	Function
new Jedis(host, port)	##CreateJedis connection, parameters: host name, port number 6379
## set(key,value)	Add a string key and value
get(key)	##Get the specified key Value
Add a	hash type key-field-value
Get its value through the	hash key-field
##Add a # from the left	##lpop(key)
Pop an element from the left	##rpop(key)
Pop an element from the right	close()
##Close the connection

##JedisPoolConfig configuration class	Function Description
JedisPoolConfig()	Create a configuration object and just use the parameterless constructor
void setMaxTotal()	Set the maximum number of connections in the connection pool
void setMaxWaitMillis()	Set the maximum waiting time to get the connection object Jedis

#JedisPool(configuration object, server nameParameter 1: The above configuration object, Parameter 2: Server name, Parameter 3: 6379##Jedis getResource()##void close()

##JedisPool connection pool class

##Description

, Port number)Create connection pool

Get a Jedis connection object from the connection pool

Connection pool closing method, usually does not close the connection pool

        3.3JedisPool的基本使用

需求：

使用连接池优化jedis操作

开发步骤

创建连接池配置对象，设置最大连接数10，设置用户最大等待时间2000毫秒

通过配置对象做为参数，创建连接池对象

从连接池里面获取jedis连接对象，执行redis命令。

执行redis命令sadd写入set集合类型的数据：students=白骨精,孙悟空,猪八戒

执行redis命令smembers读取集合中的数据

输出读取的数据

关闭连接对象(通常连接池不关闭)

运行效果

执行代码

package com.itheima.jedis;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

import java.util.Set;

/**
 * 创建Jedis连接池
 */
public class Demo2 {

    public static void main(String[] args) {
        //1)	创建连接池配置对象，设置最大连接数10，设置用户最大等待时间2000毫秒
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(10);
        config.setMaxWaitMillis(2000);
        //2)	通过配置对象做为参数，创建连接池对象
        JedisPool pool = new JedisPool(config, "localhost", 6379);
        //3)	从连接池里面获取jedis连接对象，执行redis命令。
        Jedis jedis = pool.getResource();
        //4)	执行redis命令sadd写入set集合类型的数据：students=白骨精,孙悟空,猪八戒
        jedis.sadd("students", "白骨精", "孙悟空", "猪八戒");
        //5)	执行redis命令smembers读取集合中的数据
        Set<String> students = jedis.smembers("students");
        //6)	输出读取的数据
        System.out.println(students);
        //7)	关闭连接对象(通常连接池不关闭)
        jedis.close();
        pool.close();
    }
}

4.案例：编写jedis连接池工具类

        4.1相应API的学习

java.util.ResourceBundle类是专门用于：读取类路径下Properties配置文件的类

java.util.ResourceBundle类	功能
static ResourceBundle getBundle("配置基名")	通过自己的静态方法创建ResourceBundle对象 参数：放在src下.properties文件。参数中不用写扩展名，只要有主名就可以了
String getString("键名")	通过键得到值

案例：得到druid.properties中的url属性

package com.itheima.jedis;

import java.util.ResourceBundle;

/**
 * 读取属性文件
 */
public class Demo3 {

    public static void main(String[] args) {
        //得到资源绑定对象
        ResourceBundle bundle = ResourceBundle.getBundle("druid");
        System.out.println(bundle.getString("url"));
    }

}

        4.2连接池工具类的实现

需求：

实现连接池工具类，通过工具类得到Jedis连接对象，配置参数写在属性文件中

调用工具类，对Redis数据库进行操作

执行效果：

实现步骤：

在src目录下创建连接池的工具类: jedis.properties 

创建静态成员变量JedisPool对象

在静态代码块中，读取src下的配置文件，得到ResourceBundle对象

得到上面的四个参数，其中host是字符串类型，其它参数要转成整数类型

实例化配置对象，实例化连接池对象

编写静态方法getJedis()返回Jedis对象

创建hash对象：键employee，添加字段名：name，值：NewBoy；字段名: salary，值：3000

使用hgetall读取hash对象输出

关闭jedis对象

jedis.properties配置文件

# 主机名
host=localhost
# 端口号
port=6379
# 最大连接数
maxTotal=20
# 最长等待时间
maxWaitMillis=3000

JedisUtils.java

package com.itheima.utils;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

import java.util.ResourceBundle;

/**
 * 连接池工具类
 */
public class JedisUtils {

    //创建一个连接对象
    private static JedisPool pool;

    static {
        //创建连接池的配置对象
        JedisPoolConfig config = new JedisPoolConfig();
        //设置最大连接数和最长等待时间
        ResourceBundle bundle = ResourceBundle.getBundle("jedis");
        //得到配置文件中的属性值
        String host = bundle.getString("host");
        int port = Integer.parseInt(bundle.getString("port"));
        int maxTotal = Integer.parseInt(bundle.getString("maxTotal"));
        int maxWaitMillis = Integer.parseInt(bundle.getString("maxWaitMillis"));
        //设置配置对象的参数
        config.setMaxTotal(maxTotal);
        config.setMaxWaitMillis(maxWaitMillis);
        //创建连接池对象
        pool = new JedisPool(config, host, port);
    }

    /**
     * 得到redis连接对象
     * @return
     */
    public static Jedis getJedis() {
        return pool.getResource();
    }

}

使用工具类：

package com.itheima.jedis;

import com.itheima.utils.JedisUtils;
import redis.clients.jedis.Jedis;

import java.util.Map;

/**
 * 使用工具类
 */
public class Demo4 {

    public static void main(String[] args) {
        //从工具类中得到Jedis对象
        Jedis jedis = JedisUtils.getJedis();
        //创建hash对象：键employee，添加字段名：name，值：NewBoy；字段名: salary，值：3000
        jedis.hset("employee", "name","NewBoy");
        jedis.hset("employee", "salary","3000");
        //使用hgetall读取hash对象输出
        Map<String, String> employee = jedis.hgetAll("employee");
        System.out.println(employee);
        //关闭jedis对象
        jedis.close();
    }

}

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