2-23 redis

1.概述

2.下载安装

redis中文网

3. 命令操作

3.1 数据结构

3.2 命令操作

3.3 redis持久化

如果修改完配置文件，需要按以下方式重启一下


AOF对性能要求比较大，总在持久化。
如果修改完配置文件，需要按以下方式重启一下

3.4 Jedis

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Jedis 操作五种数据结构：

package cn.itcast.jedis.test;

import org.junit.Test;
import redis.clients.jedis.Jedis;

import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * jedis 测试类
 */
public class JedisTest {
    
    

    /**
     * 快速入门
     */
    @Test
    public void test1() {
    
    
        // 1. 获取连接
        Jedis jedis = new Jedis("localhost", 6379); // ip 和 端口号
        // 2. 操作
        jedis.set("username", "zhangsan");
        // 3. 关闭拦截
        jedis.close();
    }

    @Test
    /**
     * 操作字符串 String
     */
    public void test2() {
    
    
        Jedis jedis = new Jedis(); // 如果使用空参构造，默认值为 “localhost”，6379端口
        jedis.set("username", "zhangsan");
        String name = jedis.get("username");
        System.out.println(name);

        // 可以使用setex（）方法存储，可以指定过期时间的 key value
        jedis.setex("activecode", 20, "hehe"); // 将activecode，hehe键值对存入redis，并在20秒后自动删除。

        jedis.close();
    }

    @Test
    /**
     * 操作 hash结构
     */
    public void test3() {
    
    
        Jedis jedis = new Jedis();
        //存储
        jedis.hset("user", "name", "lisi");
        jedis.hset("user", "age", "23");
        jedis.hset("user", "gender", "male");
        // 获取
        String name = jedis.hget("user", "name");
        System.out.println(name);
        // 获取所有数据
        Map<String,String> user = jedis.hgetAll("user");
        Set<String> keySet = user.keySet();
        for (String key:keySet){
    
    
            //获取value
            String value = user.get(key);
            System.out.println(key +"+" +value);
        }

        jedis.close();
    }

    @Test
    /**
     * 操作 列表 list
     */
    public void test4(){
    
    
        Jedis jedis = new Jedis();
        //存储
        jedis.lpush("mylist","a","b","c"); // cba
        jedis.rpush("mylist","a","b","c"); // abc
        // 范围获取
        List<String> mylist = jedis.lrange("mylist",0,-1);//cbaabc
        System.out.println(mylist);
        // list 弹出
        String ele1 = jedis.lpop("mylist"); //c
        System.out.println(ele1);
        String ele2 = jedis.rpop("mylist");// c
        System.out.println(ele2);

        List<String> mylist2 = jedis.lrange("mylist",0,-1);//baab
        System.out.println(mylist2);

        jedis.close();
    }

    @Test
    /**
     * 操作 set 不允许重复元素
     */
    public void test5(){
    
    
        Jedis jedis = new Jedis();
        jedis.sadd("myset","java","php","c++");
        Set<String> myset = jedis.smembers("myset");
        System.out.println(myset);
        jedis.close();
    }

    @Test
    /**
     * 操作 sortedset 不允许重复元素
     */
    public void test6(){
    
    
        Jedis jedis = new Jedis();
        jedis.zadd("mysortset",3,"lisi");
        jedis.zadd("mysortset",10,"wang");
        Set<String> mysortset = jedis.zrange("mysortset", 0, -1);
        System.out.println(mysortset);

        jedis.close();
    }
}

jedis 连接池： JedisPool

 @Test
    /**
     * jedis 连接池使用
     */
    public void test7(){
    
    

        // 0. 创建一个配置对象,还有很多配置
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(50); //最大连接数
        config.setMaxIdle(10);//空闲连接

        // 1.创建Jedis连接池对象
        JedisPool jedisPool = new JedisPool(config,"localhost",6379);
        // 2. 获取连接
        Jedis jedis = jedisPool.getResource();
        // 3. 使用
        jedis.set("username","zhang");
        String username = jedis.get("username");
        System.out.println(username);
        // 4. 关闭 归还到连接池中
        jedis.close();
    }

Jedis 连接池工具类
jedis.properties配置文件 src目录下

host=localhost
port=6379
maxTotal=50
maxIdle=10

JedisPoolUtils.java 工具类

package cn.itcast.jedis.util;

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

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

/**
 * JedisPool工具类
 *      加载配置文件，配置连接池参数
 *      提供获取连接的方法
 */
public class JedisPoolUtils {
    
    
	// 工具类一般是静态的
    private static JedisPool jedisPool;
    //静态代码块：类一加载就读取配置文件。
    static {
    
    
        //读取配置文件
        InputStream is = JedisPoolUtils.class.getClassLoader().getResourceAsStream("jedis.properties");
        //创建Properties对象
        Properties pro = new Properties();
        //关联文件
        try {
    
    
            pro.load(is);
        } catch (IOException e) {
    
    
            e.printStackTrace();
        }
        //获取数据，设置到JedisPoolConfig里
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(Integer.parseInt(pro.getProperty("maxTotal"))); //获取的一个String，要变成int
        config.setMaxIdle(Integer.parseInt(pro.getProperty("maxIdle")));

        // 初始化JedisPool
        jedisPool = new JedisPool(config,pro.getProperty("host"),Integer.parseInt(pro.getProperty("port")));
    }
    /**
     * 获取连接方法
     */
    public static Jedis getJedis(){
    
    
        return jedisPool.getResource();
    }
}

测试

@Test
    /**
     * JedisPool工具类使用
     */
    public void test8(){
    
    

        // 通过连接池工具类获取
        Jedis jedis = JedisPoolUtils.getJedis();
        // 3. 使用
        jedis.set("username","zhang");
        String username = jedis.get("username");
        System.out.println(username);
        // 4. 关闭 归还到连接池中
        jedis.close();
    }

3.5 案例

环境搭建：
1）建立数据库

CREATE DATABASE day23;
USE day23;
CREATE TABLE province(
	id INT PRIMARY KEY AUTO_INCREMENT,
	NAME VARCHAR(20) NOT NULL
);
INSERT INTO province VALUES(NULL,'北京');
INSERT INTO province VALUES(NULL,'上海');
INSERT INTO province VALUES(NULL,'广州');
INSERT INTO province VALUES(NULL,'陕西');

SELECT * FROM province;

domain文件夹，定义数据库中存储的数据
Province.java

package cn.itcast.domain;

public class Province {
    
    
    private int id;
    private String name;

    public int getId() {
    
    
        return id;
    }

    public void setId(int id) {
    
    
        this.id = id;
    }

    public String getName() {
    
    
        return name;
    }

    public void setName(String name) {
    
    
        this.name = name;
    }
}

util文件夹 工具类
JDBCUtils.java

package cn.itcast.util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Collections;
import java.util.Properties;

/**
 * JDBC工具类 Durid连接池
 */
public class JDBCUtils {
    
    
    private static DataSource ds; // 数据库连接池对象

    static {
    
    

        try {
    
    
            // 1.加载配置文件
            Properties pro = new Properties();
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);

            // 2. 初始化连接池对象
            ds = DruidDataSourceFactory.createDataSource(pro);
        } catch (IOException e) {
    
    
            e.printStackTrace();
        } catch (Exception e) {
    
    
            e.printStackTrace();
        }
    }

    /**
     * 获取连接池对象
     *
     */
    public static DataSource getDataSource(){
    
    
        return ds;
    }

    /**
     * 获取连接Connection对象
     */
    public static Connection getConnection() throws SQLException {
    
    
        return ds.getConnection();
    }

}

druid.properties

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///day23
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000

dao文件夹执行sql语句
ProvinceDao接口

package cn.itcast.dao;

import cn.itcast.domain.Province;

import java.util.List;

public interface ProvinceDao {
    
    
    public List<Province> findAll();
}

ProvinceDaoImpl。java实现类

package cn.itcast.dao;

import cn.itcast.domain.Province;
import cn.itcast.util.JDBCUtils;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;

public class ProvinceDaoImpl implements ProvinceDao{
    
    

    // 1. 声明成员变量 jdbctemplement
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    @Override
    public List<Province> findAll() {
    
    
        // 1.定义sql
        String sql = "select * from province";
        // 2. 执行sql
        List<Province> list = template.query(sql,new BeanPropertyRowMapper<Province>(Province.class));

        return list;
    }
}

service文件夹
接口

package cn.itcast.service;

import cn.itcast.domain.Province;

import java.util.List;

public interface ProvinceService {
    
    
    public List<Province> findAll();
}

实现类

package cn.itcast.service;

import cn.itcast.dao.ProvinceDao;
import cn.itcast.dao.ProvinceDaoImpl;
import cn.itcast.domain.Province;

import java.util.List;

public class ProvinceServiceImpl implements ProvinceService{
    
    

    private ProvinceDao dao = new ProvinceDaoImpl();

    @Override
    public List<Province> findAll() {
    
    
        return dao.findAll();
    }
}

web。servlet文件夹

package cn.itcast.web.servlet;

import cn.itcast.domain.Province;
import cn.itcast.service.ProvinceService;
import cn.itcast.service.ProvinceServiceImpl;
import com.fasterxml.jackson.databind.ObjectMapper;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet("/ProvinceServlet")
public class ProvinceServlet extends HttpServlet {
    
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
        // 1. 调用service查询
        ProvinceService service = new ProvinceServiceImpl();
        List<Province> list = service.findAll();
        // 2. 序列化list转为json
        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(list);
        //System.out.println(json);
        // 3. 响应结果
        resp.setContentType("application/json;charset=utf-8");
        resp.getWriter().write(json);
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
        this.doPost(req, resp);
    }
}

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="js/jquery-3.3.1.min.js"></script>
    <script>
        $(function () {
    
    
            //发送ajax请求，加载所有省份
            $.get("ProvinceServlet",{
    
    },function (data) {
    
    
               // [{"id":1,"name":"北京"},{"id":2,"name":"上海"},{"id":3,"name":"广州"},{"id":4,"name":"陕西"}]
                //1.获取select
                var province = $("#province");
                // 2.遍历json数组
                $(data).each(function () {
    
    
                    //3.创建<option>
                    var option = "<option name='"+this.id+"'>"+this.name+"</option>";
                    // 4.调用select的append追加option
                    province.append(option);
                });

            });
        });
    </script>
</head>
<body>

<select id="province">
    <option>--请选择省份--</option>
</select>

</body>
</html>

service的接口

package cn.service;

import cn.domain.Province;

import java.util.List;

public interface ProvinceService {
    
    
    public List<Province> findAll();

    public String findAllJson();
}

service的实现类

package cn.service;

import cn.dao.ProvinceDao;
import cn.dao.ProvinceDaoImpl;
import cn.domain.Province;
import cn.jedis.util.JedisPoolUtils;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import redis.clients.jedis.Jedis;

import java.util.List;

public class ProvinceServiceImpl implements ProvinceService{
    
    

    ProvinceDao dao = new ProvinceDaoImpl();
    @Override
    public List<Province> findAll() {
    
    
        List<Province> list = dao.findAll();
        return list;
    }

    /**
     * 使用redis缓存
     * @return
     */
    @Override
    public String findAllJson() {
    
    
        // 1. 先从redis查询数据
        // 1.1 获取redis客户端连接
        Jedis jedis = JedisPoolUtils.getJedis();
        String province_json = jedis.get("province");

        // 2. 判断 province_json数据是否为null
        if (province_json == null || province_json.length()==0){
    
    
            // redis中没有数据
            System.out.println("redis没数据，查询数据库...");
            // 2.1从数据库中查询
            List<Province> ps = dao.findAll();
            // 2.2序列化json
            ObjectMapper mapper = new ObjectMapper();
            try {
    
    
                province_json = mapper.writeValueAsString(ps);
            } catch (JsonProcessingException e) {
    
    
                e.printStackTrace();
            }
            // 2.3 将json数据存入redis
            jedis.set("province",province_json);
            jedis.close();
        }
        return province_json;
    }
}

还有servlet需修改

package cn.web.servlet;

import cn.domain.Province;
import cn.service.ProvinceService;
import cn.service.ProvinceServiceImpl;
import com.fasterxml.jackson.databind.ObjectMapper;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet("/ProvinceServlet")
public class ProvinceServlet extends HttpServlet {
    
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
        /*ProvinceService service = new ProvinceServiceImpl();
        List<Province> list = service.findAll();
        //序列化为json
        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(list);*/

        // 采用redis方式
        ProvinceService service =new ProvinceServiceImpl() ;
        String json = service.findAllJson();
        //响应结果
        resp.setContentType("application/json;charset=utf-8");
        resp.getWriter().write(json);
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
        this.doPost(req, resp);
    }
}