如何使用redis作为缓存，增强用户访问数据的用户体验

/**完成步骤 
         1、创建关系型数据库mysql的Provice库，同时启动nosql系列的redis数据库
         2、创建项目，导入相关的jar包
         3、创建jedis/utils/domain/dao/service/web项目框架包
         4、书写相关代码
*/
//页面
html>
lang="en">

 charset="UTF-8">
 
 
 


 name="province" id="province">
 --请选择省份--
 



//Web层代码实现

package cn.hope.web.servlet;

import cn.hope.domain.Province;
import cn.hope.service.ProvinceService;
import cn.hope.service.impl.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;

/**
 * @author newcityman
 * @date 2019/9/20 - 23:57
 */
@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 provinces = service.findAll();
 //2、序列化list为json数据
 ObjectMapper mapper = new ObjectMapper();
 String json = mapper.writeValueAsString(provinces);*/
// System.out.println(json);
 //1、调用service查询
 ProvinceService service = new ProvinceServiceImpl();
 String json = service.findAllJson();
 //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);
 }
}

//service层

package cn.hope.service.impl;

import cn.hope.dao.ProvinceDao;
import cn.hope.dao.impl.ProvinceDaoImpl;
import cn.hope.domain.Province;
import cn.hope.jedis.utils.JedisPoolUtils;
import cn.hope.service.ProvinceService;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;

import java.util.List;

/**
 * @author newcityman
 * @date 2019/9/20 - 23:50
 */
public class ProvinceServiceImpl implements ProvinceService {
//申明dao
 private ProvinceDao dao = new ProvinceDaoImpl();
 @Override
 public List findAll() {
return dao.findAll();
 }

@Override
 public String findAllJson() {
//1、通过工具类获取redis连接
 Jedis jedis = JedisPoolUtils.getJedis();
 //2、获取redis中province的值
 String province_json = jedis.get("province");
 //3、判断province_json值是否为null
 if(province_json == null || province_json.length()<=0){
//4、说明redis中没有province的数据,需要从数据库中查找数据
 List ps = dao.findAll();
 ObjectMapper mapper = new ObjectMapper();
 try {
 province_json = mapper.writeValueAsString(ps);
 } catch (JsonProcessingException e) {
 e.printStackTrace();
 }
 System.out.println("第一次访问redis，数据来之数据库。。。。");
 jedis.set("province",province_json);
 //释放jedis，回归连接池
 jedis.close();
 }else {
 System.out.println("数据来之redis缓存。。。。");
 }
return province_json;
 }
}

//dao层

package cn.hope.dao.impl;

import cn.hope.dao.ProvinceDao;
import cn.hope.domain.Province;
import cn.hope.utils.JDBCUtils;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;

/**
 * @author newcityman
 * @date 2019/9/20 - 23:29
 */
public class ProvinceDaoImpl implements ProvinceDao {
//1、声明成员变量JdbcTemplate
 private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
 @Override
 public List findAll() {
//1、定义sql语句
 String sql = "select * from province";
 //2、执行sql
 List list = template.query(sql, new BeanPropertyRowMapper(Province.class));
 System.out.println(list);
 return list;
 }
}

//Jedis工具包

package cn.hope.jedis.utils;

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;

/**
 * @author newcityman
 * @date 2019/9/20 - 0:33
 * JedisPool工具类
 * 加载配置文件，配置连接池的连接池
 * 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 prop = new Properties();
 try {
 prop.load(is);
 } catch (IOException e) {
 e.printStackTrace();
 }
//获取数据，设置到JedisPoolConfig()中
 JedisPoolConfig config = new JedisPoolConfig();
 config.setMaxIdle(Integer.parseInt( prop.getProperty("maxTotal")));
 config.setMaxTotal(Integer.parseInt(prop.getProperty("maxIdle")));
 jedisPool=new JedisPool(config,prop.getProperty("host"),Integer.parseInt(prop.getProperty("port")));
 }

/**
 * 获取连接方法
 * @return
 */
 public static Jedis getJedis(){
return jedisPool.getResource();
 }
}

//JDBCUtils工具包

package cn.hope.utils;

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();
 }
}

转载于:https://www.cnblogs.com/newcityboy/p/11565158.html