[SPARK-21016][core]Improve code fault tolerance for converting string to number

[10110346]

What changes were proposed in this pull request?

When converting string to number(int, long or double), if the string has a space before or after,will lead to unnecessary mistakes.

How was this patch tested?

unit test

[wzhfy]

If a string has a leading or trailing space, it's expected it cannot be converted to a number.
Java's string type also follows this convention.

[10110346]

But it can be converted to double.
If a string has a leading or trailing space, we are not easy to detect, especially the user configuration,this Pr is to solve this problem.

[kiszk]

It would be good to do the same thing for s.toBoolean in toBoolean method.

[HyukjinKwon]

I think it will be more persuasive if there are some cases where users mistakenly write wrong values for both numbers and booleans. Personally, I haven't got any errors about this before (more than two years in production / development).

[10110346]

@HyukjinKwon I agree with you ,but i think if add trim', it would be better

[gatorsmile]

Although it is not a common user error, it does not hurt to add an extra trim.

[gatorsmile]

ok to test

[SparkQA]

Test build #77917 has started for PR 18238 at commit 04307c6.

[SparkQA]

Test build #77921 has finished for PR 18238 at commit 9317956.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[srowen]

I'm neutral. Accepting bad input isn't usually a great idea, though in this case, I can't see much harm. It's not ambiguous.

[SparkQA]

Test build #77930 has finished for PR 18238 at commit c09eaa1.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[gatorsmile]

retest this please

[SparkQA]

Test build #77944 has finished for PR 18238 at commit c09eaa1.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #77966 has started for PR 18238 at commit c09eaa1.

[10110346]

Jenkins, retest this please

[SparkQA]

Test build #77982 has finished for PR 18238 at commit c09eaa1.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[gatorsmile]

Thanks! Merging to master.