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
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
|
##del(key) | Delete the specified key and value
|
##hset(key,field, value)
|
Add a |
hash type key-field-value | ##hget(key,field)
Get its value through the |
hash key-field | lpush(key,values)
|
##Add a # from the left | ##List type keys and elements##lpop(key) |
Pop an element from the left |
##rpop(key) |
Pop an element from the right |
close() |
| ##Close the connection
|
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();
}
}Copy after login
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
##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 connection pool class |
##Description |
#JedisPool(configuration object, server name, Port number)Create connection pool | Parameter 1: The above configuration object, Parameter 2: Server name, Parameter 3: 6379
|
##Jedis getResource()
Get a Jedis connection object from the connection pool |
| ##void close()
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();
}
}Copy after login 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"));
}
}Copy after login 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 Copy after login 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();
}
}Copy after login 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();
}
}Copy after login 推荐学习：Redis视频教程
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