正则表达式来解析带有嵌套引号的csv [重复]

Question

可能重复：
C#, regular expressions : how to parse comma-separated values, where some values might be quoted strings themselves containing commas
regex to parse csv

我知道这个问题已经问过很多次了，但答案却不尽相同；我很困惑。

我的行是：

1,3.2,BCD,"qwer 47"" ""dfg""",1

可选引用和双引号 MS Excel 标准。 （数据：qwer 47" "dfg"是这样表示的"qwer 47"" ""dfg"""。）

我需要一个正则表达式。

Answer 1

好的，您已经从 cmets 看到 regex 是 所以 不是正确的工具。但如果你坚持，这里是：

此正则表达式可在 Java（或 .NET 和其他支持所有格量​​词和详细正则表达式的实现）中工作：

^            # Start of string
(?:          # Match the following:
 (?:         #  Either match
  [^",\n]*+  #   0 or more characters except comma, quote or newline
 |           #  or
  "          #   an opening quote
  (?:        #   followed by either
   [^"]*+    #    0 or more non-quote characters
  |          #   or
   ""        #    an escaped quote ("")
  )*         #   any number of times
  "          #   followed by a closing quote
 )           #  End of alternation
 ,           #  Match a comma (separating the CSV columns)
)*           # Do this zero or more times.
(?:          # Then match
 (?:         #  using the same rules as above
  [^",\n]*+  #  an unquoted CSV field
 |           #  or a quoted CSV field
  "(?:[^"]*+|"")*"
 )           #  End of alternation
)            # End of non-capturing group
$            # End of string

Java 代码：

boolean foundMatch = subjectString.matches(
    "(?x)^         # Start of string\n" +
    "(?:           # Match the following:\n" +
    " (?:          #  Either match\n" +
    "  [^\",\\n]*+ #   0 or more characters except comma, quote or newline\n" +
    " |            #  or\n" +
    "  \"          #   an opening quote\n" +
    "  (?:         #   followed by either\n" +
    "   [^\"]*+    #    0 or more non-quote characters\n" +
    "  |           #   or\n" +
    "   \"\"       #    an escaped quote (\"\")\n" +
    "  )*          #   any number of times\n" +
    "  \"          #   followed by a closing quote\n" +
    " )            #  End of alternation\n" +
    " ,            #  Match a comma (separating the CSV columns)\n" +
    ")*            # Do this zero or more times.\n" +
    "(?:           # Then match\n" +
    " (?:          #  using the same rules as above\n" +
    "  [^\",\\n]*+ #  an unquoted CSV field\n" +
    " |            #  or a quoted CSV field\n" +
    "  \"(?:[^\"]*+|\"\")*\"\n" +
    " )            #  End of alternation\n" +
    ")             # End of non-capturing group\n" +
    "$             # End of string");

请注意，您不能假定 CSV 文件中的每一行都是完整的行。您可以在 CSV 行中包含换行符（只要包含换行符的列括在引号中）。这个正则表达式知道这一点，但如果你只给它部分行它会失败。这也是您真正需要 CSV 解析器来验证 CSV 文件的另一个原因。这就是解析器所做的。如果您控制自己的输入并且知道在 CSV 字段中永远不会有换行符，那么您可能会侥幸逃脱，但只有这样。

Answer 2

我已经有一段时间没有做 Java 了，所以这里有一个伪代码来做这件事。您可以将其用作接受代表 csv 行的字符串的函数。

1. Split the row by "'" delimiter into an array of strings. (method might be called string.split())
2. Iterate through the array (cells).
    3. If the current string (cell) contains a double quote:
        4. If it doesn't start with a quote - return false; else remove that quote
        5. If it doesn't end with a quote - return false; else remove that quote
        6. Iterate through the remaining characters of the string
            7. If a quote is found, check if the next character is also a quote - if it is not - return false
        7. End character iteration
    8. End if
9. End array iteration
10. Return true

Answer 3

我使用这篇博客文章中的正则表达式，这与您尝试解决的问题大致相同。

在这里查看：http://www.kimgentes.com/worshiptech-web-tools-page/2008/10/14/regex-pattern-for-parsing-csv-files-with-embedded-commas-dou.html

简而言之^(("(?:[^"]|"")*"|[^,]*)(,("(?:[^"]|"")*"|[^,]*))*)$