redis入門實戰四：jedis連接池化配置抽離及緩存

1、對jedis連接池進行配置。使用jedis連接池初衷：jedis每次獲取都要創建，不如創建池化的然後每次從連接池獲取，用完再放回去，省去創建銷燬的工序，也是比較省時的。

2、對於客戶端經常訪問不常變化的數據列表，可以使用redis來降低服務器頻繁被訪問帶給數據庫的壓力。

下面是結合上面描述編寫的樣例：
1）在項目中引入jar包

 <dependency>
    <groupId>commons-beanutils</groupId>
    <artifactId>commons-beanutils</artifactId>
    <version>1.8.3</version>
</dependency>
<dependency>
    <groupId>commons-logging</groupId>
    <artifactId>commons-logging</artifactId>
    <version>1.1.1</version>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.0.9</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.2.3</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.2.3</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.2.3</version>
</dependency>
<dependency>
    <groupId>org.glassfish.web</groupId>
    <artifactId>javax.servlet.jsp.jstl</artifactId>
    <version>1.2.5</version>
</dependency>
<dependency>
    <groupId>org.glassfish.web</groupId>
    <artifactId>jstl-impl</artifactId>
    <version>1.2</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.18</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-beans</artifactId>
    <version>4.2.4.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
    <version>4.2.4.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>4.2.4.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-tx</artifactId>
    <version>4.2.4.RELEASE</version>
</dependency>

2 )、新建JedisPoolUtil.java

package com.stu.jedis.util;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

public class jedisPoolUtils { //把jedis連接池配置信息用文件加載形式
    static JedisPool jedisPool;
    static {
        //加載jedis連接池配置文件信息,也可以直接放在src下面，直接取屬性文件名稱+後綴即可
        InputStream inStream = jedisPoolUtils.class.getClassLoader()
                .getResourceAsStream("com/stu/jedis/jedis.properties");

        Properties properties = new Properties();
        try {
            //加載屬性文件獲取常量值
            properties.load(inStream);

            //設置jedis連接池配置信息
            JedisPoolConfig poolConfig = new JedisPoolConfig();
            poolConfig.setMaxIdle(Integer.parseInt(properties.getProperty("maxIdle")));
            poolConfig.setMaxTotal(Integer.parseInt(properties.getProperty("maxTotal")));
            //創建jedis連接池
            jedisPool = new JedisPool(poolConfig, properties.getProperty("host"),
                    Integer.parseInt(properties.getProperty("port")));
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public static Jedis getJedis() {
        return jedisPool.getResource();
    }
}

3 )、在類路徑下增加屬性文件，或者直接在com/stu/jedis/ 路徑下增加屬性文件 jedis.properties

host=127.0.0.1
port=6379
maxTotal=50
maxIdle=10

4 ) 在service實現類裏添加方法

 /**
  使用redis緩存前端經常訪問或者數據較多的列表數據，且不經常變動的，可以第一次查詢就存入redis緩存，之後可以從緩存直接獲取數據。
     */
    public String findAllJson() {
        //獲取redis客戶端連接
        Jedis jedis = jedisPoolUtils.getJedis();
        String province_json = jedis.get("province");
        //2從redis中查數據，判斷否爲null
        if (province_json == null || province_json.length() == 0) {
            //redis中沒有數據
            System.out.println("redis無數據，執行查庫操作");
            //查詢數據並且存入redis
            List<Province> ps = dao.findAll();
            //將list序列化爲json
            ObjectMapper mapper = new ObjectMapper();
            try {
                province_json = mapper.writeValueAsString(ps);
            } catch (JsonProcessingException e) {
                e.printStackTrace();
            }
           //將json數據存入redis
            jedis.set("province", province_json);
            //歸還jedis連接
            jedis.close();
        } else {
            System.out.println("redis中有數據，走緩存查詢");
        }
        return province_json;
    }

5）如果數據會有修改，刪除，新增的可能，則在修改該數據方法裏，刪除之前緩存的鍵值。