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

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：

[java] view plain copy

print ?

1. @Bean  
2.    public JedisConnectionFactory connectionFactory(){  
3.        JedisConnectionFactory jedisConnectionFactory = new JedisConnectionFactory();  
4.        jedisConnectionFactory.setUsePool(true);  
5.        jedisConnectionFactory.setPoolConfig(jedisPoolConfig());  
6.        jedisConnectionFactory.setHostName(environment.getProperty(”redis.host”));  
7.        jedisConnectionFactory.setPort(Integer.parseInt(environment.getProperty(”redis.port”)));  
8.        return jedisConnectionFactory;  
9.    }  

 @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

[java] view plain copy

print ?

1. jedisConnectionFactory.afterPropertiesSet();  

 jedisConnectionFactory.afterPropertiesSet();

看源码便知原因：看jedis如何获取到连接的：

[java] view plain copy

print ?

1. public JedisConnection getConnection() {  
2.         Jedis jedis = fetchJedisConnector();  
3.         JedisConnection connection = (usePool ? new JedisConnection(jedis, pool, dbIndex) : new JedisConnection(jedis,  
4.                 null, dbIndex));  
5.         connection.setConvertPipelineAndTxResults(convertPipelineAndTxResults);  
6.         return postProcessConnection(connection);  
7.     }  

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：

[java] view plain copy

print ?

1. protected Jedis fetchJedisConnector() {  
2.         try {  
3.             if (usePool && pool != null) {  
4.                 return pool.getResource();  
5.             }  
6.             Jedis jedis = new Jedis(getShardInfo());  
7.             // force initialization (see Jedis issue #82)  
8.             jedis.connect();  
9.             return jedis;  
10.         } catch (Exception ex) {  
11.             throw new RedisConnectionFailureException(“Cannot get Jedis connection”, ex);  
12.         }  
13.     }  

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：

[java] view plain copy

print ?

1. public void afterPropertiesSet() {  
2.         if (shardInfo == null) {  
3.             shardInfo = new JedisShardInfo(hostName, port);  
4.   
5.             if (StringUtils.hasLength(password)) {  
6.                 shardInfo.setPassword(password);  
7.             }  
8.   
9.             if (timeout > 0) {  
10.                 setTimeoutOn(shardInfo, timeout);  
11.             }  
12.         }  
13.   
14.         if (usePool) {  
15.             this.pool = createPool();  
16.         }  
17.     }  

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：

[java] view plain copy

print ?

1. jedisConnectionFactory.afterPropertiesSet();  

 jedisConnectionFactory.afterPropertiesSet();

这句就可以啦。再运行一次，连接成功！