Spring RedisTemplate 批量获取值的2种方式

1、利用mGet

List keys = new ArrayList<>();
//初始keys
List list = this.redisTemplate.opsForValue().multiGet(keys);

2、利用PipeLine

List list = this.redisTemplate.executePipelined(new RedisCallback() {
    @Override
    public YourObject doInRedis(RedisConnection connection) throws DataAccessException {
        StringRedisConnection conn = (StringRedisConnection)connection;
        for (String key : keys) {
            conn.get(key);
        }
        return null;
    }
});

其实2者底层都是用到execute方法，multiGet在使用连接是没用到pipeline，一条命令直接传给Redis，Redis返回结果。而executePipelined实际上一条或多条命令，但是共用一个连接。

    /**
     * Executes the given action object within a connection that can be exposed or not. Additionally, the connection can
     * be pipelined. Note the results of the pipeline are discarded (making it suitable for write-only scenarios).
     *
     * @param  return type
     * @param action callback object to execute
     * @param exposeConnection whether to enforce exposure of the native Redis Connection to callback code
     * @param pipeline whether to pipeline or not the connection for the execution
     * @return object returned by the action
     */
    public  T execute(RedisCallback action, boolean exposeConnection, boolean pipeline) {
        Assert.isTrue(initialized, "template not initialized; call afterPropertiesSet() before using it");
        Assert.notNull(action, "Callback object must not be null");

        RedisConnectionFactory factory = getConnectionFactory();
        RedisConnection conn = null;
        try {

            if (enableTransactionSupport) {
                // only bind resources in case of potential transaction synchronization
                conn = RedisConnectionUtils.bindConnection(factory, enableTransactionSupport);
            } else {
                conn = RedisConnectionUtils.getConnection(factory);
            }

            boolean existingConnection = TransactionSynchronizationManager.hasResource(factory);

            RedisConnection connToUse = preProcessConnection(conn, existingConnection);

            boolean pipelineStatus = connToUse.isPipelined();
            if (pipeline && !pipelineStatus) { //开启管道
                connToUse.openPipeline();
            }

            RedisConnection connToExpose = (exposeConnection ? connToUse : createRedisConnectionProxy(connToUse));
            T result = action.doInRedis(connToExpose);

            if (pipeline && !pipelineStatus) {// 关闭管道
                connToUse.closePipeline();
            }

            // TODO: any other connection processing?
            return postProcessResult(result, connToUse, existingConnection);
        } finally {

            if (!enableTransactionSupport) {
                RedisConnectionUtils.releaseConnection(conn, factory);
            }
        }
    }

还有一点，就是查询返回的结果，和键的顺序是一一对应的，如果没查到，会返回null值。