What is the regular expression to remove spaces in

问题:

In a Regex, how to remove all the leading, trailing and where ever spaces exist in SOLR. To remove special characters, we can have the PatternReplaceFilterFactory as

<filter class="solr.PatternReplaceFilterFactory" pattern="([^a-z])" replacement="" replace="all" />

What pattern value will be formed to remove the spaces whereever it comes.

回答1:

I don't know SOLR but based on your example I guess you could just do

<filter class="solr.PatternReplaceFilterFactory" pattern="(\s+)" replacement="" replace="all" /> to remove all spaces

or

<filter class="solr.PatternReplaceFilterFactory" pattern="(^\s+|\s+$)" replacement="" replace="all" /> to remove just leading and trailing spaces.

回答2:

Use the trim filter to remove leading and trailing spaces. http://wiki.apache.org/solr/AnalyzersTokenizersTokenFilters#solr.TrimFilterFactory

just replacing everything not a-z with nothing will cause strange things to happen and is not a good idea.

回答3:

solr.TrimFilterFactory , can be used to remove leading and trailing spaces without regex.