Redis_案例_hehe.employment.over.23.6

文章目錄

• 23.9 Redis_案例
• • 23.9.1 案例需求
  • 23.9.2 示例
  • • Province
    • JDBCUtils
    • JedisPoolUtils
    • ProvinceDao
    • ProvinceDaoImpl
    • ProvinceService
    • ProvinceServiceImpl
    • ProvinceServlet
    • index.html

23.9 Redis_案例

23.9.1 案例需求

- 1.提供index.html頁面，頁面中有一個省份 下拉清單;
 - 2.當 頁面加載完成後 發送ajax請求，加載所有省份。
 - ***notes***：使用redis緩存一些不經常發生變化的資料。	
 - 資料庫的資料一旦發生改變，則需要更新緩存;
 - 資料庫的表執行 增删改的相關操作，需要将redis緩存資料情況，再次存入	;
 - 在service對應的增删改方法中，将redis資料删除。
 - ***圖示：***
           

23.9.2 示例

Province

package com.xww.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;
    }
}

           

JDBCUtils

package com.xww.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工具類 使用Durid連接配接池
 */
public class JDBCUtils {

    private static DataSource ds ;

    static {

        try {
            //1.加載配置檔案
            Properties pro = new Properties();
            //使用ClassLoader加載配置檔案，擷取位元組輸入流
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);

            //2.初始化連接配接池對象
            ds = DruidDataSourceFactory.createDataSource(pro);

        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 擷取連接配接池對象
     */
    public static DataSource getDataSource(){
        return ds;
    }


    /**
     * 擷取連接配接Connection對象
     */
    public static Connection getConnection() throws SQLException {
        return  ds.getConnection();
    }
}

           

JedisPoolUtils

package com.xww.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工具類
 加載配置檔案，配置連接配接池的參數
 提供擷取連接配接的方法
 */
public class JedisPoolUtils {

    private static JedisPool jedisPool;

    static{
        //讀取配置檔案
        InputStream is = JedisPoolUtils.class.getClassLoader().getResourceAsStream("jedis.properties");
        //建立Properties對象
        Properties pro = new Properties();
        //關聯檔案
        try {
            pro.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        //擷取資料，設定到JedisPoolConfig中
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(Integer.parseInt(pro.getProperty("maxTotal")));
        config.setMaxIdle(Integer.parseInt(pro.getProperty("maxIdle")));
        //初始化JedisPool
        jedisPool = new JedisPool(config,pro.getProperty("host"),Integer.parseInt(pro.getProperty("port")));
    }

    /**
     * 擷取連接配接方法
     */
    public static Jedis getJedis(){
        return jedisPool.getResource();
    }
}

           

ProvinceDao

package com.xww.dao;

import com.xww.domain.Province;

import java.util.List;

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

           

ProvinceDaoImpl

package com.xww.dao.impl;

import com.xww.dao.ProvinceDao;
import com.xww.domain.Province;
import com.xww.util.JDBCUtils;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;

public class ProvinceDaoImpl implements ProvinceDao{
    //1.聲明成員變量 jdbctemplement
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

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

           

ProvinceService

package com.xww.service;

import com.xww.domain.Province;

import java.util.List;

public interface ProvinceService {

    public List<Province> findAll();
    public String findAllJson();
}

           

ProvinceServiceImpl

package com.xww.service.impl;

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

import java.util.List;

public class ProvinceServiceImpl implements ProvinceService {
    //聲明dao
    private ProvinceDao dao = new ProvinceDaoImpl();

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

    /**
     使用redis緩存
     */
    @Override
    public String findAllJson() {
        //1.先從redis中查詢資料
        //1.1擷取redis用戶端連接配接
        Jedis jedis = JedisPoolUtils.getJedis();
        String province_json = jedis.get("province");

        //2判斷 province_json 資料是否為null
        if(province_json == null || province_json.length() == 0){
            //redis中沒有資料
            System.out.println("redis中沒資料，查詢資料庫...");
            //2.1從資料中查詢
            List<Province> ps = dao.findAll();
            //2.2将list序列化為json
            ObjectMapper mapper = new ObjectMapper();
            try {
                province_json = mapper.writeValueAsString(ps);
            } catch (JsonProcessingException e) {
                e.printStackTrace();
            }
            //2.3 将json資料存入redis
            jedis.set("province",province_json);
            //歸還連接配接
            jedis.close();
        }else{
            System.out.println("redis中有資料，查詢緩存...");
        }
        return province_json;
    }
}

           

ProvinceServlet

package com.xww.web.servlet;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.xww.domain.Province;
import com.xww.service.ProvinceService;
import com.xww.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;
import java.util.List;

@WebServlet("/provinceServlet")
public class ProvinceServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //redis緩存
        //1.調用service查詢
        ProvinceService service = new ProvinceServiceImpl();
        String json = service.findAllJson();
        System.out.println(json);
        //3.響應結果
        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);
    }
}

           

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 () {
            //發送ajax請求，加載所有省份資料
            $.get("provinceServlet",{},function (data) {
                //[{"id":1,"name":"北京"},{"id":2,"name":"上海"},{"id":3,"name":"廣州"},{"id":4,"name":"陝西"}]

                //1.擷取select
                var province = $("#province");
                //2.周遊json數組
                $(data).each(function () {
                    //3.建立<option>
                    var option = "<option name='"+this.id+"'>"+this.name+"</option>";

                    //4.調用select的append追加option
                    province.append(option);
                });
            });
        });
    </script>
    
</head>
<body>
        <select id="province">
            <option>--請選擇省份--</option>
        </select>
</body>
</html>