java 正则表达式中的空格
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Blank spaces in regular expression
提问by sfrj
I use this regular to validate many of the input fields of my java web app:
我使用这个常规来验证我的 java web 应用程序的许多输入字段：
"^[a-zA-Z0-9]+$"
But i need to modify it, because i have a couple of fields that need to allow blank spaces(for example: Address).
但我需要修改它，因为我有几个字段需要允许空格（例如：地址）。
How can i modify it to allow blank spaces(if possible not at the start).
我如何修改它以允许空格（如果可能的话不在开头）。
I think i need to use some scape character like \
我想我需要使用一些像 \
I tried a few different combinations but none of them worked. Can somebody help me with this regex?
我尝试了几种不同的组合，但都没有奏效。有人可以帮我处理这个正则表达式吗？
回答by darioo
I'd suggest using this:
我建议使用这个：
^[a-zA-Z0-9][a-zA-Z0-9 ]+$
It adds two things: first, you're guaranteed not to have a space at the beginning, while allowing characters you need. Afterwards, letters a-zand A-Zare allowed, as well as all digits and spaces (there's a space at the end of my regex).
它增加了两件事：首先，你保证开头没有空格，同时允许你需要的字符。之后，允许使用字母a-z和A-Z，以及所有数字和空格（我的正则表达式末尾有一个空格）。
回答by Oscar Mederos
If you want to use only a whitespace, you can do:
如果只想使用空格，可以执行以下操作：
^[a-zA-Z0-9 ]+$
^[a-zA-Z0-9 ]+$
If you want to include tabs\t, new-line\n\r\ncharacters, you can do:
如果要包含tabs\t，换行符\n\r\n，可以执行以下操作：
^[a-zA-Z0-9\s]+$
^[a-zA-Z0-9\s]+$
Also, as you asked, if you don't want the whitespace to be at the begining:
另外，正如您所问的，如果您不希望空格在开头：
^[a-zA-Z0-9][a-zA-Z0-9 ]+$
^[a-zA-Z0-9][a-zA-Z0-9 ]+$
回答by Arnab Das
Use this: ^[a-zA-Z0-9]+[a-zA-Z0-9 ]+$. This should work. First atom ensures that there must be at least one character at beginning.
使用这个：^[a-zA-Z0-9]+[a-zA-Z0-9 ]+$。这应该有效。第一个原子确保开头必须至少有一个字符。
回答by Mahesh KP
try like this ^[a-zA-Z0-9 ]+$ that is, add a space in it
试试这样 ^[a-zA-Z0-9 ]+$ 即，在其中添加一个空格
回答by Gursel Koca
This regex dont allow spaces at the end of string, one downside it accepts underscore character also.
这个正则表达式不允许在字符串末尾有空格，一个缺点是它也接受下划线字符。
^(\w+ )+\w+|\w+$
回答by Lekensteyn
Try this one: I assume that any input with a length of at least one character is valid. The previously mentioned answers does not take that into account.
试试这个：我假设任何长度至少为一个字符的输入都是有效的。前面提到的答案没有考虑到这一点。
"^[a-zA-Z0-9][a-zA-Z0-9 ]*$"
If you want to allow all whitespace characters, replace the space by "\s"
如果要允许所有空格字符，请将空格替换为“\s”
