Redis-学习笔记06【Redis案例】

偏执的太偏执、 2022-10-31 04:18 187阅读 0赞

>  *  **[Java后端 学习路线 笔记汇总表【黑马程序员】][Java_ _]**
> 
> 1.  [Redis-学习笔记01【Redis环境搭建】][Redis-_01_Redis]
> 2.  [Redis-学习笔记02【Redis命令操作】][Redis-_02_Redis]
> 3.  [Redis-学习笔记03【Redis持久化】][Redis-_03_Redis]
> 4.  [Redis-学习笔记04【Jedis代码操作】][Redis-_04_Jedis]
> 5.  [Redis-学习笔记05【Jedis连接池】][Redis-_05_Jedis]
> 6.  [Redis-学习笔记06【Redis案例】][Redis-_06_Redis]

**目录**

第6节 Redis案例

案例\_分析&环境搭建

day23.sql

druid.properties

案例\_实现\_查询数据库

案例\_实现\_redis缓存优化

package cn.itcast.dao;

ProvinceDaoImpl.java

ProvinceDao.java

package cn.itcast.domain;

Province.java

package cn.itcast.jedis;

JedisPoolUtils.java

package cn.itcast.service;

ProvinceServiceImpl.java

ProvinceService.java

package cn.itcast.util;

JDBCUtils.java

package cn.itcast.web;

ProvinceServlet.java

web

index.html

--------------------

# 第6节 Redis案例 #

## 案例\_分析&环境搭建 ##

> **案例**
> 
> 案例需求：  
>     1. 提供index.html页面，页面中有一个省份（下拉列表）。  
>     2. 当页面加载完成后，发送ajax请求，加载所有省份。

> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70][] 案例

> ![20210221152548282.png][]

### day23.sql ###

> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70 1][]

CREATE DATABASE day23; -- 创建数据库
    USE day23; 			   -- 使用数据库
    CREATE TABLE province(   -- 创建表
    	id INT PRIMARY KEY AUTO_INCREMENT,
    	NAME VARCHAR(20) NOT NULL
    	
    );
    -- 插入数据
    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');

### druid.properties ###

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

> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70 2][]  ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70 3][]

## 案例\_实现\_查询数据库 ##

> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70 4][]
> 
> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70 5][]

## 案例\_实现\_redis缓存优化 ##

> \* 注意：使用redis缓存一些不经常发生变化的数据。  
>     \* 数据库的数据一旦发生改变，则需要更新缓存。  
>         \* 数据库的表执行“增删改”的相关操作，需要将redis缓存数据清空，再次存入。  
>         \* 在service对应的增删改方法中，将redis数据删除。

> ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDk0OTEzNQ_size_16_color_FFFFFF_t_70 6][]

## package cn.itcast.dao; ##

### ProvinceDaoImpl.java ###

package cn.itcast.dao.impl;
    
    import cn.itcast.dao.ProvinceDao;
    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;
        }
    }

### ProvinceDao.java ###

package cn.itcast.dao;
    
    import cn.itcast.domain.Province;
    
    import java.util.List;
    
    public interface ProvinceDao {
        public List<Province> findAll();
    }

## package cn.itcast.domain; ##

### 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;
        }
    }

## package cn.itcast.jedis; ##

### JedisPoolUtils.java ###

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，配置连接池的参数
     * 提供获取连接的方法
     */
    public class JedisPoolUtils {
        private static JedisPool jedisPool;
    
        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中
            JedisPoolConfig config = new JedisPoolConfig();
            //pro.getProperty("maxTotal")：获取的值是字符串，配置要求的是int值
            config.setMaxTotal(Integer.parseInt(pro.getProperty("maxTotal")));//最大连接数
            config.setMaxIdle(Integer.parseInt(pro.getProperty("maxIdle")));//最大空闲连接数
            //初始化JedisPool对象
            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();//获取连接
        }
    }

## package cn.itcast.service; ##

### ProvinceServiceImpl.java ###

package cn.itcast.service.impl;
    
    import cn.itcast.dao.ProvinceDao;
    import cn.itcast.dao.impl.ProvinceDaoImpl;
    import cn.itcast.domain.Province;
    import cn.itcast.jedis.util.JedisPoolUtils;
    import cn.itcast.service.ProvinceService;
    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 {
        //声明dao
        private ProvinceDao dao = new ProvinceDaoImpl();
    
        @Override
        public List<Province> findAll() {
            return dao.findAll();
        }
    
        /**
         * 使用redis缓存
         */
        @Override
        public String findAllJson() {
            //1.先从redis中查询数据
            //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中没数据，查询数据库...");
                //2.1从数据中查询
                List<Province> ps = dao.findAll();
                //2.2将list序列化为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);
                //归还连接
                jedis.close();
            } else {
                System.out.println("redis中有数据，查询缓存...");
            }
            return province_json;
        }
    }

### ProvinceService.java ###

package cn.itcast.service;
    
    import cn.itcast.domain.Province;
    
    import java.util.List;
    
    public interface ProvinceService {
        public List<Province> findAll();
        public String findAllJson();
    }

## package cn.itcast.util; ##

### 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.Properties;
    
    /**
     * JDBC工具类 使用Durid连接池
     */
    public class JDBCUtils {
        private static DataSource ds;
    
        static {
            try {
                //1.加载配置文件
                Properties pro = new Properties();
                //使用ClassLoader加载配置文件，获取字节输入流
                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();
        }
    }

## package cn.itcast.web; ##

### ProvinceServlet.java ###

package cn.itcast.web.servlet;
    
    import cn.itcast.service.ProvinceService;
    import cn.itcast.service.impl.ProvinceServiceImpl;
    
    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;
    
    @WebServlet("/provinceServlet")
    public class ProvinceServlet extends HttpServlet {
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           /* //1.调用service查询
            ProvinceService service = new ProvinceServiceImpl();
            List<Province> list = service.findAll();
            //2.序列化list为json
            ObjectMapper mapper = new ObjectMapper();
            String json = mapper.writeValueAsString(list);*/
    
            //1.调用service查询
            ProvinceService service = new ProvinceServiceImpl();
            String json = service.findAllJson();
    
            System.out.println(json);
            //3.响应结果
            response.setContentType("application/json;charset=utf-8");
            response.getWriter().write(json);
    
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doPost(request, response);
        }
    }

## web ##

### 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，加载所有省份数据
                $.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>

> 加油~~~

[Java_ _]: https://blog.csdn.net/weixin_44949135/article/details/113773297
[Redis-_01_Redis]: https://blog.csdn.net/weixin_44949135/article/details/113875866
[Redis-_02_Redis]: https://blog.csdn.net/weixin_44949135/article/details/113914406
[Redis-_03_Redis]: https://blog.csdn.net/weixin_44949135/article/details/113915303
[Redis-_04_Jedis]: https://blog.csdn.net/weixin_44949135/article/details/113916097
[Redis-_05_Jedis]: https://blog.csdn.net/weixin_44949135/article/details/113917558
[Redis-_06_Redis]: https://blog.csdn.net/weixin_44949135/article/details/113918656
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[20210221152548282.png]: /images/20221024/70662a17068a459ca8cb393620e32263.png
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