而DataStream#print每10秒打印一次结果，我很想知道下面发生了什么？
这是因为DataStream.print()实际上将打印操作视为接收器：

/**
 * Writes a DataStream to the standard output stream (stdout).
 *
 * <p>For each element of the DataStream the result of {@link Object#toString()} is written.
 *
 * <p>NOTE: This will print to stdout on the machine where the code is executed, i.e. the Flink
 * worker.
 *
 * @return The closed DataStream.
 */
@PublicEvolving
public DataStreamSink<T> print() {
    PrintSinkFunction<T> printFunction = new PrintSinkFunction<>();
    return addSink(printFunction).name("Print to Std. Out");
}

所以你会看到每10秒就有一个结果被写出来，因为你正在以相同的速率向流生成一个新消息，消息通过流，最终被写到接收器，接收器只是打印出标准输出。
TableResult#print每3分钟打印一次结果，这似乎与检查点间隔有关。
这一点您也是正确的，如果您看一下TableResult.print()，它与下面接口中定义的检查点间隔密切相关：

/**
 * Print the result contents as tableau form to client console.
 *
 * <p>This method has slightly different behaviors under different checkpointing settings (to
 * enable checkpointing for a streaming job, set checkpointing properties through {@link
 * TableConfig}).
 *
 * <ul>
 *   <li>For batch jobs or streaming jobs without checkpointing, this method has neither
 *       exactly-once nor at-least-once guarantee. Query results are immediately accessible by
 *       the clients once they're produced, but exceptions will be thrown when the job fails and
 *       restarts.
 *   <li>For streaming jobs with exactly-once checkpointing, this method guarantees an
 *       end-to-end exactly-once record delivery. A result will be accessible by clients only
 *       after its corresponding checkpoint completes.
 *   <li>For streaming jobs with at-least-once checkpointing, this method guarantees an
 *       end-to-end at-least-once record delivery. Query results are immediately accessible by
 *       the clients once they're produced, but it is possible for the same result to be
 *       delivered multiple times.
 * </ul>
 *
 * <p>In order to fetch result to local, you can call either {@link #collect()} and {@link
 * #print()}. But, they can't be called both on the same {@link TableResult} instance, because
 * the result can only be accessed once.
 */
void print();