spring-data-redis用配置类连接时，抛异常Cannot get Jedis connection; nested exception is java.lang.NullPointerEx

梦里梦外; 2023-06-16 07:54 5阅读 0赞

转载自：[http://www.voidcn.com/article/p-zuhwqgmf-dq.html][http_www.voidcn.com_article_p-zuhwqgmf-dq.html]

## 叙述 ##

redis服务器已经运行，且端口号，服务器地址都已经配置正常，但任然抛出无法获取连接异常

**Cannot get Jedis connection; nested exception is java.lang.NullPointerEx**

## 解决方案 ##

代码

@Bean
        public JedisConnectionFactory connectionFactory(){
            JedisConnectionFactory jedisConnectionFactory = new JedisConnectionFactory();
            jedisConnectionFactory.setUsePool(true);
            jedisConnectionFactory.setPoolConfig(jedisPoolConfig());
            jedisConnectionFactory.setHostName(environment.getProperty("redis.host"));
            jedisConnectionFactory.setPort(Integer.parseInt(environment.getProperty("redis.port")));
            return jedisConnectionFactory;
        }

其他配置都很正常，但是运行后会抛出空指针异常。

Request processing failed; nested exception is org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection; nested exception is java.lang.NullPointerException

解决方法如下，在return前添加如下代码

看源码便知原因：看jedis如何获取到连接的：

public JedisConnection getConnection() {
    		Jedis jedis = fetchJedisConnector();
    		JedisConnection connection = (usePool ? new JedisConnection(jedis, pool, dbIndex) : new JedisConnection(jedis,
    				null, dbIndex));
    		connection.setConvertPipelineAndTxResults(convertPipelineAndTxResults);
    		return postProcessConnection(connection);
    	}

我们看fetchJedisConnector()方法：

protected Jedis fetchJedisConnector() {
    		try {
    			if (usePool && pool != null) {
    				return pool.getResource();
    			}
    			Jedis jedis = new Jedis(getShardInfo());
    			// force initialization (see Jedis issue #82)
    			jedis.connect();
    			return jedis;
    		} catch (Exception ex) {
    			throw new RedisConnectionFailureException("Cannot get Jedis connection", ex);
    		}
    	}

如果没用用pool的话，需要用到getShardInfo()方法，而这个方法就是返回一个JedisShardInfo shardInfo。那么这个JedisShardInfo shardInfo在什么时候初始化呢？查看后发现，哈哈在这：

public void afterPropertiesSet() {
    		if (shardInfo == null) {
    			shardInfo = new JedisShardInfo(hostName, port);
    
    			if (StringUtils.hasLength(password)) {
    				shardInfo.setPassword(password);
    			}
    
    			if (timeout > 0) {
    				setTimeoutOn(shardInfo, timeout);
    			}
    		}
    
    		if (usePool) {
    			this.pool = createPool();
    		}
    	}

这个方法将在所有的属性被初始化后调用。但是会在init前调用。是spring中InitializingBean接口的方法。spring-data-redis里面实现了它。在这里对shardIndo类进行了初始化。所以，我们只要在代码中添加：

jedisConnectionFactory.afterPropertiesSet();

这句就可以啦。再运行一次，连接成功！

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spring-data-redis用配置类连接时，抛异常Cannot get Jedis connection; nested exception is java.lang.NullPointerEx

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