Redis简单配置和使用

1. windows启动redis-server要配置一下maxheap 10240000，否则报错“To work around this you may either increase the size of the system paging file, or decrease the size of the Redis heap with the --maxheap flag”

2. 使用配置项requirepass xxxxxx为redis配置强密码，参考漏洞《Redis 未授权访问缺陷可轻易导致系统被黑》

3. redis主从配置也很简单，从redis使用配置项slaveof 192.168.0.118 6379配置主redis，如果主redis设置了密码，从redis需使用配置项masterauth xxxxxx配置访问主redis的密码，从redis和主redis都要设置密码。

4. windows redis客户端使用命令redis-cli -h 192.168.0.118 -p 6379 -a password启动

5. 进一步提高性能的措施：读写分离、redis集群

6. redis官网：http://redis.io/


Jedis的简单代码示例

  1. Jedis官网：https://github.com/xetorthio/jedis

  2. Jedis对象不是线程安全的

  3. 简单示例

    public static void test(String[] args) {
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(10);
        config.setMaxIdle(5);
        config.setTestOnBorrow(true);

        JedisPool pool = new JedisPool(config, serverIp, serverPort, timeout, passwrod);
        
        if (pool != null) {
            Jedis jedis = pool.getResource();
            try {
                Set<String> keys = jedis.keys("*");
                System.out.println(keys);
            }
            catch (JedisConnectionException e) {
                if (jedis != null) {
                    pool.returnBrokenResource(jedis);
                    jedis = null;
                }
            }
            finally {
                if (jedis != null) {
                    pool.returnResource(jedis);
                }
            }
        }
    }

4. 《Jedis returnResource使用注意事项》提到，不能不管什么情况都一律使用returnResource，其中的示例调整为如下

    public static void test(String[] args) {
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(10);
        config.setMaxIdle(5);
        config.setTestOnBorrow(true);

        JedisPool pool = new JedisPool(config, serverIp, serverPort, timeout, passwrod);

        Jedis jedis = null;
        boolean broken = false;
        if (pool != null) {
            try {
                jedis = pool.getResource();
                Set<String> keys = jedis.keys("*");
                System.out.println(keys);
            }
            catch (JedisException e) {
                broken = handleJedisException(e);
                throw e;
            }
            finally {
                closeResource(pool, jedis, broken);
            }
            
            pool.destroy();
        }

    }

    private static boolean handleJedisException(JedisException jedisException) {
        if (jedisException instanceof JedisConnectionException) {
            logger.error("Redis connection lost.", jedisException);
        }
        else if (jedisException instanceof JedisDataException) {
            if ((jedisException.getMessage() != null) && (jedisException
                    .getMessage().indexOf("READONLY") != -1)) {
                logger.error("Redis connection are read-only slave.",
                        jedisException);
            }
            else {
                // dataException, isBroken=false
                return false;
            }
        }
        else {
            logger.error("Jedis exception happen.", jedisException);
        }
        return true;
    }

    /**
     * Return jedis connection to the pool, call different return methods
     * depends on the conectionBroken status.
     */
    protected static void closeResource(JedisPool pool, Jedis jedis,
            boolean conectionBroken) {
        try {
            if (conectionBroken) {
                pool.returnBrokenResource(jedis);
            }
            else {
                pool.returnResource(jedis);
            }
        }
        catch (Exception e) {
            logger.error("return back jedis failed, will fore close the jedis.",
                    e);
            destroyJedis(jedis);
        }
    }

    public static void destroyJedis(Jedis jedis) {
        if ((jedis != null) && jedis.isConnected()) {
            try {
                try {
                    jedis.quit();
                }
                catch (Exception e) {
                }
                jedis.disconnect();
            }
            catch (Exception e) {
            }
        }
    }

  关于此代码，原帖下有人回复“是不是没有配置 testOnBorrow = true？ 如果配置了这个参数，每次取jedis时，都会测试 jedis.isConnected和ping一下服务端的。”。