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

前提：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

原来的代码如下：

 @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

 jedisConnectionFactory.afterPropertiesSet();

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！