redis使用入門介紹

redis使用入門介紹

本文以IDEA爲例簡單介紹redis及jedis的配置及使用說明。

一、IDEA導入相關依賴

		<dependency>
			<groupId>redis.clients</groupId>
			<artifactId>jedis</artifactId>
		</dependency>

二、配置文件中配置redis

本例配置文件爲application.properties

redis.host=127.0.0.1
redis.port=6379
redis.timeout=10
redis.poolMaxTotal=1000
redis.poolMaxIdle=500
redis.poolMaxWait=500

三、在實體類中讀取配置文件中redis的配置信息

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

/**
 * 讀取配置文件中關於redis的配置信息
 */

@Component
@ConfigurationProperties(prefix = "redis")      // 在application.properties中，讀取前綴”redis“的配置信息
public class RedisConfig {
    private String host;
    private int port;
    private int timeout;
    private String password;
    private int poolMaxTotal;
    private int poolMaxIdle;
    private int poolMaxWait;

    public String getHost() {
        return host;
    }

    public void setHost(String host) {
        this.host = host;
    }

    public int getPort() {
        return port;
    }

    public void setPort(int port) {
        this.port = port;
    }

    public int getTimeout() {
        return timeout;
    }

    public void setTimeout(int timeout) {
        this.timeout = timeout;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public int getPoolMaxTotal() {
        return poolMaxTotal;
    }

    public void setPoolMaxTotal(int poolMaxTotal) {
        this.poolMaxTotal = poolMaxTotal;
    }

    public int getPoolMaxIdle() {
        return poolMaxIdle;
    }

    public void setPoolMaxIdle(int poolMaxIdle) {
        this.poolMaxIdle = poolMaxIdle;
    }

    public int getPoolMaxWait() {
        return poolMaxWait;
    }

    public void setPoolMaxWait(int poolMaxWait) {
        this.poolMaxWait = poolMaxWait;
    }
}

四、自定義redis連接池

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Service;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

/**
 * 自定義redis連接池JedisPool，並注入spring容器
 */
@Service
public class RedisPoolFactory {

    @Autowired
    RedisConfig  redisConfig;

    /**
     * 將redis連接池注入spring容器
     * @return
     */
    @Bean
    public JedisPool JedisPoolFactory(){
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxIdle(redisConfig.getPoolMaxIdle());
        config.setMaxTotal(redisConfig.getPoolMaxTotal());
        config.setMaxWaitMillis(redisConfig.getPoolMaxWait() * 1000);
        // 連接池參數設置
        JedisPool jp = new JedisPool(config, redisConfig.getHost(), redisConfig.getPort(),
                redisConfig.getTimeout()*1000, redisConfig.getPassword(), 0);
        return jp;
    }
}

五、redis過期時間及前綴的定義

1. 先定義一個接口

/**
 *包含方法：
 *      有效期
 *      獲取前綴
 */
public interface KeyPrefix {

    /**
     * 有效期
     * @return
     */
    public int expireSeconds();

    /**
     * 前綴
     * @return
     */
    public String getPrefix();
}

2. 實現接口

public abstract class BasePrefix implements KeyPrefix {

    private int expireSeconds;  //過期時間

    private String prefix;      //前綴

    public BasePrefix(String prefix){
        this(0, prefix);//默認0代表永不過期
    }

    public BasePrefix(int expireSeconds, String prefix){
        this.expireSeconds = expireSeconds;
        this.prefix = prefix;
    }

    @Override
    public int expireSeconds() {
        return expireSeconds;
    }

    @Override
    public String getPrefix() {
        String className = getClass().getSimpleName();//拿到參數類類名
        return className + ":" + prefix;
    }
}

六、自定義redis的服務

import com.alibaba.fastjson.JSON;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;

/**
 * redis服務
 */
@Service
public class RedisService {

    @Autowired
    JedisPool jedisPool;

    /**
     * 從redis連接池獲取redis實例
     */
    public <T> T get(KeyPrefix prefix, String key, Class<T> clazz) {
        Jedis jedis = null;
        try {
            jedis = jedisPool.getResource();        // 從連接池中獲取一個jedis連接
            //對key增加前綴，即可用於分類，也避免key重複
            String realKey = prefix.getPrefix() + key;  // 類名+key
            String str = jedis.get(realKey);
            T t = stringToBean(str, clazz);
            return t;
        } finally {
            returnToPool(jedis);
        }

    }

    /**
     * 存儲對象
     */
    public <T> Boolean set(KeyPrefix prefix, String key, T value) {
        Jedis jedis = null;
        try {
            jedis = jedisPool.getResource();
            String str = beanToString(value);
            if (str == null || str.length() <= 0) {
                return false;
            }
            String realKey = prefix.getPrefix() + key;
            int seconds = prefix.expireSeconds();//獲取過期時間
            if (seconds <= 0) {
                jedis.set(realKey, str);
            } else {
                jedis.setex(realKey, seconds, str);
            }

            return true;
        } finally {
            returnToPool(jedis);    //使用結束，將jedis返回連接池
        }

    }

    /**
     * 刪除
     */
    public boolean delete(KeyPrefix prefix, String key) {
        Jedis jedis = null;
        try {
            jedis = jedisPool.getResource();
            //生成真正的key
            String realKey = prefix.getPrefix() + key;
            long ret = jedis.del(realKey);          // 如果刪除了一個或多個鍵，則爲大於0的整數，如果指定的鍵不存在，則爲0
            return ret > 0;         // 測試是否刪除成功，刪除成功返回true
        } finally {
            returnToPool(jedis);    // 使用結束，將jedis返回連接池
        }
    }

    /**
     * 判斷key是否存在
     */
    public <T> boolean exists(KeyPrefix prefix, String key) {
        Jedis jedis = null;
        try {
            jedis = jedisPool.getResource();
            //生成真正的key
            String realKey = prefix.getPrefix() + key;
            return jedis.exists(realKey);       // 判斷是否已經存在key
        } finally {
            returnToPool(jedis);                // 使用結束，將jedis返回連接池
        }
    }

    /**
     * 增加值
     * Redis Incr 命令將 key 中儲存的數字值增一。    如果 key 不存在，那麼 key 的值會先被初始化爲 0 ，然後再執行 INCR 操作
     */
    public <T> Long incr(KeyPrefix prefix, String key) {
        Jedis jedis = null;
        try {
            jedis = jedisPool.getResource();
            //生成真正的key
            String realKey = prefix.getPrefix() + key;
            return jedis.incr(realKey);
        } finally {
            returnToPool(jedis);
        }
    }

    /**
     * 減少值
     */
    public <T> Long decr(KeyPrefix prefix, String key) {
        Jedis jedis = null;
        try {
            jedis = jedisPool.getResource();
            //生成真正的key
            String realKey = prefix.getPrefix() + key;
            return jedis.decr(realKey);
        } finally {
            returnToPool(jedis);
        }
    }


    public static <T> String beanToString(T value) {
        if (value == null) {
            return null;
        }
        Class<?> clazz = value.getClass();
        if (clazz == int.class || clazz == Integer.class) {
            return String.valueOf(value);
        } else if (clazz == long.class || clazz == Long.class) {
            return String.valueOf(value);
        } else if (clazz == String.class) {
            return (String) value;
        } else {
            return JSON.toJSONString(value);
        }

    }

    public static <T> T stringToBean(String str, Class<T> clazz) {
        if (str == null || str.length() <= 0 || clazz == null) {
            return null;
        }
        if (clazz == int.class || clazz == Integer.class) {
            return (T) Integer.valueOf(str);
        } else if (clazz == long.class || clazz == Long.class) {
            return (T) Long.valueOf(str);
        } else if (clazz == String.class) {
            return (T) str;
        } else {
            return JSON.toJavaObject(JSON.parseObject(str), clazz);
        }
    }

    /**
     * 作用：//將jedis返回到連接池中，目的是節省jedis資源
     * @param jedis
     */
    private void returnToPool(Jedis jedis) {
        if (jedis != null) {
            jedis.close();
        }
    }
}

七、使用示例

import com.alibaba.druid.util.StringUtils;
import com.jesper.seckill.bean.User;
import com.jesper.seckill.exception.GlobalException;
import com.jesper.seckill.mapper.UserMapper;
import com.jesper.seckill.redis.RedisService;
import com.jesper.seckill.redis.UserKey;
import com.jesper.seckill.result.CodeMsg;
import com.jesper.seckill.util.MD5Util;
import com.jesper.seckill.util.UUIDUtil;
import com.jesper.seckill.vo.LoginVo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletResponse;

/**
 * 關於用戶的操作
 */
@Service
public class UserService {

    @Autowired
    UserMapper userMapper;

    @Autowired
    RedisService redisService;

    public static final String COOKIE_NAME_TOKEN = "token";

    /**
     * 由id獲取對應的用戶
     * @param id
     * @return
     */
    public User getById(long id) {
        //先從redis緩存中獲取用戶對象
        User user = redisService.get(UserKey.getById, "" + id, User.class);
        if (user != null) {
            return user;
        }

        // redis緩存中不存在用戶對象，從數據庫中取
        user = userMapper.getById(id);
        //再存入緩存
        if (user != null) {
            redisService.set(UserKey.getById, "" + id, user);
        }
        return user;
    }
}