我有一些文件解析器代码，我偶尔会在m.matches（）上获得堆栈溢出错误（其中m是匹配器）。
我再次运行我的应用程序，它解析相同的文件，没有堆栈溢出。
我的模式确实有点复杂。它基本上是一堆可选的零长度正向前瞻，其中包含命名组，因此我可以匹配一堆变量名称/值对，而不管它们的顺序如何。但我希望，如果某些字符串会导致堆栈溢出错误，它总是会导致它......不仅仅是有时......任何想法？
我的模式的简化版本
"prefix(?=\\s+user=(?<user>\\S+))?(?=\\s+repo=(?<repo>\\S+))?.*?"
完整的正则表达式是......
app=github(?=(?:[^"]|"[^"]*")*\s+user=(?<user>\S+))?(?=(?:[^"]|"[^"]*")*\s+repo=(?<repo>\S+))?(?=(?:[^"]|"[^"]*")*\s+remote_address=(?<ip>\S+))?(?=(?:[^"]|"[^"]*")*\s+now="(?<time>\S+)\+\d\d:\d\d")?(?=(?:[^"]|"[^"]*")*\s+url="(?<url>\S+)")?(?=(?:[^"]|"[^"]*")*\s+referer="(?<referer>\S+)")?(?=(?:[^"]|"[^"]*")*\s+status=(?<status>\S+))?(?=(?:[^"]|"[^"]*")*\s+elapsed=(?<elapsed>\S+))?(?=(?:[^"]|"[^"]*")*\s+request_method=(?<requestmethod>\S+))?(?=(?:[^"]|"[^"]*")*\s+created_at="(?<createdat>\S+)(?:-|\+)\d\d:\d\d")?(?=(?:[^"]|"[^"]*")*\s+pull_request_id=(?<pullrequestid>\d+))?(?=(?:[^"]|"[^"]*")*\s+at=(?<at>\S+))?(?=(?:[^"]|"[^"]*")*\s+fn=(?<fn>\S+))?(?=(?:[^"]|"[^"]*")*\s+method=(?<method>\S+))?(?=(?:[^"]|"[^"]*")*\s+current_user=(?<user2>\S+))?(?=(?:[^"]|"[^"]*")*\s+content_length=(?<contentlength>\S+))?(?=(?:[^"]|"[^"]*")*\s+request_category=(?<requestcategory>\S+))?(?=(?:[^"]|"[^"]*")*\s+controller=(?<controller>\S+))?(?=(?:[^"]|"[^"]*")*\s+action=(?<action>\S+))?.*?
堆栈顶部溢出错误堆栈...（它长约9800行）
Exception: java.lang.StackOverflowError
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4480)
at java.util.regex.Pattern$CharProperty.match(Pattern.java:3706)
at java.util.regex.Pattern$Branch.match(Pattern.java:4516)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4570)
at java.util.regex.Pattern$Loop.match(Pattern.java:4697)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4629)
我遇到错误的行示例。 （虽然我已经运行了10次，但没有收到任何错误）
app=github env=production enterprise=true auth_fingerprint=\"token:6b29527b:9.99.999.99\" controller=\"Api::GitCommits\" path_info=\"/api/v3/repos/XYZ-ABCDE/abcdefg-abc/git/commits/77ae1376f969059f5f1e23cc5669bff8cca50563.diff\" query_string=nil version=v3 auth=oauth current_user=abcdefghijk oauth_access_id=24 oauth_application_id=0 oauth_scopes=\"gist,notifications,repo,user\" route=\"/repositories/:repository_id/git/commits/:id\" org=XYZ-ABCDE oauth_party=personal repo=XYZ-ABCDE/abcdefg-abc repo_visibility=private now=\"2015-09-24T13:44:52+00:00\" request_id=675fa67e-c1de-4bfa-a965-127b928d427a server_id=c31404fc-b7d0-41a1-8017-fc1a6dce8111 remote_address=9.99.999.99 request_method=get content_length=92 content_type=\"application/json; charset=utf-8\" user_agent=nil accept=application/json language=nil referer=nil x_requested_with=nil status=404 elapsed=0.041 url=\"https://git.abc.abcd.abc.com/api/v3/repos/XYZ-ABCDE/abcdefg-abc/git/commits/77ae1376f969059f5f1e23cc5669bff8cca50563.diff\" worker_request_count=77192 request_category=apiapp=github env=production enterprise=true auth_fingerprint=\"token:6b29527b:9.99.999.99\" controller=\"Api::GitCommits\" path_info=\"/api/v3/repos/XYZ-ABCDE/abcdefg-abc/git/commits/9bee255c7b13c589f4e9f1cb2d4ebb5b8519ba9c.diff\" query_string=nil version=v3 auth=oauth current_user=abcdefghijk oauth_access_id=24 oauth_application_id=0 oauth_scopes=\"gist,notifications,repo,user\" route=\"/repositories/:repository_id/git/commits/:id\" org=XYZ-ABCDE oauth_party=personal repo=XYZ-ABCDE/abcdefg-abc repo_visibility=private now=\"2015-09-24T13:44:52+00:00\" request_id=89fcb32e-9ab5-47f7-9464-e5f5cff175e8 server_id=1b74880a-5124-4483-adce-111b60dac111 remote_address=9.99.999.99 request_method=get content_length=92 content_type=\"application/json; charset=utf-8\" user_agent=nil accept=application/json language=nil referer=nil x_requested_with=nil status=404 elapsed=0.024 url=\"https://git.abc.abcd.abc.com/api/v3/repos/XYZ-ABCDE/abcdefg-abc/git/commits/9bee255c7b13c589f4e9f1cb2d4ebb5b8519ba9c.diff\" worker_request_count=76263 request_category=api
答案 0 :(得分：11)
有两种方法可以解决您的问题：
正确解析输入字符串并从Map获取键值。
我强烈建议您使用此方法，因为代码会更清晰，我们不再需要查看输入大小的限制。
修改现有的正则表达式，以大大减少导致StackOverflowError的实现缺陷的影响。
您可以使用以下正则表达式解析输入字符串：
\G\s*+(\w++)=([^\s"]++|"[^"]*+")(?:\s++|$)
所有量词都具有占有性（*+而不是*，++而不是+），因为我写的模式不需要回溯。
您可以找到基本正则表达式(\w++)=([^\s"]++|"[^"]*+")以匹配中间的键值对。
\G是为了确保匹配从最后一场比赛的开始处开始。它用于防止引擎在无法匹配时“碰撞”。
\s*+和(?:\s++|$)用于消耗多余的空间。我指定(?:\s++|$)而不是\s*+，以防止key="value"key=value被识别为有效输入。
完整的示例代码可以在下面找到：
private static final Pattern KEY_VALUE = Pattern.compile("\\G\\s*+(\\w++)=([^\\s\"]++|\"[^\"]*+\")(?:\\s++|$)");
public static Map<String, String> parseKeyValue(String kvString) {
Matcher matcher = KEY_VALUE.matcher(kvString);
Map<String, String> output = new HashMap<String, String>();
int lastIndex = -1;
while (matcher.find()) {
output.put(matcher.group(1), matcher.group(2));
lastIndex = matcher.end();
}
// Make sure that we match everything from the input string
if (lastIndex != kvString.length()) {
return null;
}
return output;
}
您可能希望根据您的要求取消引用这些值。
您还可以重写函数以传递要提取的List个键，然后在while循环中选择它们以避免存储您不关心的键。
问题是由于外部重复(?:[^"]|"[^"]*")*通过递归实现，当输入字符串足够长时导致StackOverflowError。
具体而言，在每次重复中，它匹配引用的标记或单个非引用的字符。结果，堆栈随着非引用字符的数量线性增长而爆炸。
您可以将(?:[^"]|"[^"]*")*的所有实例替换为[^"]*(?:"[^"]*"[^"]*)*。堆栈现在将作为引用令牌的数量线性增长，因此不会发生StackOverflowError，除非输入字符串中有数千个引用的令牌。
Pattern KEY_CAPTURE = Pattern.compile("app=github(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+user=(?<user>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+repo=(?<repo>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+remote_address=(?<ip>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+now=\"(?<time>\\S+)\\+\\d\\d:\\d\\d\")?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+url=\"(?<url>\\S+)\")?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+referer=\"(?<referer>\\S+)\")?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+status=(?<status>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+elapsed=(?<elapsed>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+request_method=(?<requestmethod>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+created_at=\"(?<createdat>\\S+)(?:-|\\+)\\d\\d:\\d\\d\")?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+pull_request_id=(?<pullrequestid>\\d+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+at=(?<at>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+fn=(?<fn>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+method=(?<method>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+current_user=(?<user2>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+content_length=(?<contentlength>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+request_category=(?<requestcategory>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+controller=(?<controller>\\S+))?(?=[^\"]*(?:\"[^\"]*\"[^\"]*)*\\s+action=(?<action>\\S+))?");
它遵循正则表达式(A|B)*→A*(BA*)*的等效扩展。哪个用作A或B取决于它们的重复次数 - 无论哪个重复都应该是A而另一个应该是B.
StackOverflowError中的{p> Pattern是一个已知问题，当您的模式包含重复非确定性 1 捕获/时，可能会发生此问题非捕获组，在您的情况下是子模式(?:[^"]|"[^"]*")*。
1 这是Pattern源代码中使用的术语，可能旨在表明模式已修复长度。但是，无论实际模式如何，实施都认为交替|是非确定性的。
非确定性捕获/非捕获组的贪婪或懒惰重复被编译到Loop / LazyLoop类中，这些类通过递归实现重复。因此，此类模式极易触发StackOverflowError，尤其是当该组包含一次只匹配单个字符的分支时。
另一方面， deterministic 2 重复，占有重复和重复独立组(?>...)（又名 atomic group或 non-backtracking group）被编译成Curly / GroupCurly类，在大多数情况下会循环处理重复，所以会有没有StackOverflowError。
2 重复模式是一个字符类，或一个固定长度的捕获/非捕获组，没有任何替换
您可以在下面看到如何编译原始正则表达式的片段。记下有问题的部分，它以Loop开头，并将其与堆栈跟踪进行比较。
app=github(?=(?:[^"]|"[^"]*")*\s+user=(?<user>\S+))?(?=(?:[^"]|"[^"]*")*\s+repo=(?<repo>\S+))?
BnM. Boyer-Moore (BMP only version) (length=10)
app=github
Ques. Greedy optional quantifier
Pos. Positive look-ahead
GroupHead. local=0
Prolog. Loop wrapper
Loop [1889ca51]. Greedy quantifier {0,2147483647}
GroupHead. local=1
Branch. Alternation (in printed order):
CharProperty.complement. S̄:
BitClass. Match any of these 1 character(s):
"
---
Single. Match code point: U+0022 QUOTATION MARK
Curly. Greedy quantifier {0,2147483647}
CharProperty.complement. S̄:
BitClass. Match any of these 1 character(s):
"
Node. Accept match
Single. Match code point: U+0022 QUOTATION MARK
---
BranchConn [7e41986c]. Connect branches to sequel.
GroupTail [47e1b36]. local=1, group=0. --[next]--> Loop [1889ca51]
Curly. Greedy quantifier {1,2147483647}
Ctype. POSIX (US-ASCII): SPACE
Node. Accept match
Slice. Match the following sequence (BMP only version) (length=5)
user=
GroupHead. local=3
Curly. Greedy quantifier {1,2147483647}
CharProperty.complement. S̄:
Ctype. POSIX (US-ASCII): SPACE
Node. Accept match
GroupTail [732c7887]. local=3, group=2. --[next]--> GroupTail [6c9d2223]
GroupTail [6c9d2223]. local=0, group=0. --[next]--> Node [4ea5d7f2]
Node. Accept match
Node. Accept match
Ques. Greedy optional quantifier
Pos. Positive look-ahead
GroupHead. local=4
Prolog. Loop wrapper
Loop [402c5f8a]. Greedy quantifier {0,2147483647}
GroupHead. local=5
Branch. Alternation (in printed order):
CharProperty.complement. S̄:
BitClass. Match any of these 1 character(s):
"
---
Single. Match code point: U+0022 QUOTATION MARK
Curly. Greedy quantifier {0,2147483647}
CharProperty.complement. S̄:
BitClass. Match any of these 1 character(s):
"
Node. Accept match
Single. Match code point: U+0022 QUOTATION MARK
---
BranchConn [21347df0]. Connect branches to sequel.
GroupTail [7d382897]. local=5, group=0. --[next]--> Loop [402c5f8a]
Curly. Greedy quantifier {1,2147483647}
Ctype. POSIX (US-ASCII): SPACE
Node. Accept match
Slice. Match the following sequence (BMP only version) (length=5)
repo=
GroupHead. local=7
Curly. Greedy quantifier {1,2147483647}
CharProperty.complement. S̄:
Ctype. POSIX (US-ASCII): SPACE
Node. Accept match
GroupTail [71f111ba]. local=7, group=4. --[next]--> GroupTail [9c304c7]
GroupTail [9c304c7]. local=4, group=0. --[next]--> Node [4ea5d7f2]
Node. Accept match
Node. Accept match
LastNode.
Node. Accept match
答案 1 :(得分：3)
最终答案：
将此(?:[^"]|"[^"]*")*功能移动到具有
的备用组
其他。
它无法破碎！
附注 - 我注意到你说你删除了一个换行符并最终得到了 一条记录的末尾没有隔板之间的分隔符，
像这样request_category=apiapp=github没关系，但这些正则表达式会在它击中时大部分被它击败
\S+。因此，最好将
\S+替换为(?:(?!app=github)\S)+，
这不是在下面的正则表达式中完成的。 以下是添加的内容：
"(?s)app=github(?>\\s+user=(?<user>(?:(?!app=github)\\S)+)|\\s+repo=(?<repo>(?:(?!app=github)\\S)+)|\\s+remote_address=(?<ip>(?:(?!app=github)\\S)+)|\\s+now=\\\\?\"(?<time>(?:(?!app=github)\\S)+)\\+\\d\\d:\\d\\d\\\\?\"|\\s+url=\\\\?\"(?<url>(?:(?!app=github)\\S)+)\\\\?\"|\\s+referer=\\\\?\"(?<referer>(?:(?!app=github)\\S)+)\\\\?\"|\\s+status=(?<status>(?:(?!app=github)\\S)+)|\\s+elapsed=(?<elapsed>(?:(?!app=github)\\S)+)|\\s+request_method=(?<requestmethod>(?:(?!app=github)\\S)+)|\\s+created_at=\\\\?\"(?<createdat>(?:(?!app=github)\\S)+)[-+]\\d\\d:\\d\\d\\\\?\"|\\s+pull_request_id=(?<pullrequestid>\\d+)|\\s+at=(?<at>(?:(?!app=github)\\S)+)|\\s+fn=(?<fn>(?:(?!app=github)\\S)+)|\\s+method=(?<method>(?:(?!app=github)\\S)+)|\\s+current_user=(?<user2>(?:(?!app=github)\\S)+)|\\s+content_length=(?<contentlength>(?:(?!app=github)\\S)+)|\\s+request_category=(?<requestcategory>(?:(?!app=github)\\S)+)|\\s+controller=(?<controller>(?:(?!app=github)\\S)+)|\\s+action=(?<action>(?:(?!app=github)\\S)+)|\"[^\"]*\"|(?!app=github).)+"
使用该示例的链接：https://ideone.com/hdwufO
正则表达式
原始：
(?s)app=github(?>\s+user=(?<user>\S+)|\s+repo=(?<repo>\S+)|\s+remote_address=(?<ip>\S+)|\s+now=\\?"(?<time>\S+)\+\d\d:\d\d\\?"|\s+url=\\?"(?<url>\S+)\\?"|\s+referer=\\?"(?<referer>\S+)\\?"|\s+status=(?<status>\S+)|\s+elapsed=(?<elapsed>\S+)|\s+request_method=(?<requestmethod>\S+)|\s+created_at=\\?"(?<createdat>\S+)[-+]\d\d:\d\d\\?"|\s+pull_request_id=(?<pullrequestid>\d+)|\s+at=(?<at>\S+)|\s+fn=(?<fn>\S+)|\s+method=(?<method>\S+)|\s+current_user=(?<user2>\S+)|\s+content_length=(?<contentlength>\S+)|\s+request_category=(?<requestcategory>\S+)|\s+controller=(?<controller>\S+)|\s+action=(?<action>\S+)|"[^"]*"|(?!app=github).)+
Stringed：
"(?s)app=github(?>\\s+user=(?<user>\\S+)|\\s+repo=(?<repo>\\S+)|\\s+remote_address=(?<ip>\\S+)|\\s+now=\\\\?\"(?<time>\\S+)\\+\\d\\d:\\d\\d\\\\?\"|\\s+url=\\\\?\"(?<url>\\S+)\\\\?\"|\\s+referer=\\\\?\"(?<referer>\\S+)\\\\?\"|\\s+status=(?<status>\\S+)|\\s+elapsed=(?<elapsed>\\S+)|\\s+request_method=(?<requestmethod>\\S+)|\\s+created_at=\\\\?\"(?<createdat>\\S+)[-+]\\d\\d:\\d\\d\\\\?\"|\\s+pull_request_id=(?<pullrequestid>\\d+)|\\s+at=(?<at>\\S+)|\\s+fn=(?<fn>\\S+)|\\s+method=(?<method>\\S+)|\\s+current_user=(?<user2>\\S+)|\\s+content_length=(?<contentlength>\\S+)|\\s+request_category=(?<requestcategory>\\S+)|\\s+controller=(?<controller>\\S+)|\\s+action=(?<action>\\S+)|\"[^\"]*\"|(?!app=github).)+"
格式化：
(?s)
app = github
(?>
\s+
user =
(?<user> \S+ ) # (1)
|
\s+ repo =
(?<repo> \S+ ) # (2)
|
\s+ remote_address =
(?<ip> \S+ ) # (3)
|
\s+ now= \\? "
(?<time> \S+ ) # (4)
\+ \d\d : \d\d \\? "
|
\s+ url = \\? "
(?<url> \S+ ) # (5)
\\? "
|
\s+ referer = \\? "
(?<referer> \S+ ) # (6)
\\? "
|
\s+ status =
(?<status> \S+ ) # (7)
|
\s+ elapsed =
(?<elapsed> \S+ ) # (8)
|
\s+ request_method =
(?<requestmethod> \S+ ) # (9)
|
\s+ created_at = \\? "
(?<createdat> \S+ ) # (10)
[-+]
\d\d : \d\d \\? "
|
\s+ pull_request_id =
(?<pullrequestid> \d+ ) # (11)
|
\s+ at=
(?<at> \S+ ) # (12)
|
\s+ fn=
(?<fn> \S+ ) # (13)
|
\s+ method =
(?<method> \S+ ) # (14)
|
\s+ current_user =
(?<user2> \S+ ) # (15)
|
\s+ content_length =
(?<contentlength> \S+ ) # (16)
|
\s+ request_categor y=
(?<requestcategory> \S+ ) # (17)
|
\s+ controller =
(?<controller> \S+ ) # (18)
|
\s+ action =
(?<action> \S+ ) # (19)
|
" [^"]* " # None of the above, give quotes a chance
|
(?! app = github ) # Failsafe, consume a character, advance by 1
.
)+