Java Scanner 换行识别
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Java Scanner newline recognition
提问by Anthony
I can't find the documentation that specifies how a Scanner treats newline patterns by default. I want to read a file line by line and have the scanner be able to handle \r, \n or \r\n line endings regardless of the system the program is actually running on.
我找不到指定扫描仪默认如何处理换行符模式的文档。我想逐行读取文件，并使扫描仪能够处理 \r、\n 或 \r\n 行结尾，而不管程序实际运行在哪个系统上。
If I declare a scanner like so:
如果我像这样声明扫描仪：
Scanner scanner = new Scanner(reader);
what is the default behaviour? Will it handle all three kinds as described above or do I have to tell it explicitly to do it?
默认行为是什么？它会处理上述所有三种类型，还是我必须明确告诉它这样做？
回答by David
Looking at the source code for Sun JDK 1.6, the pattern used is "\r\n|[\n\r\u2028\u2029\u0085]"
查看Sun JDK 1.6的源代码，使用的模式是“\r\n|[\n\r\u2028\u2029\u0085]”
which says "\r\n" or any one of \r, \n or the unicode characters for "line separator", "paragraph separator", and "next line" respectively.
它分别表示“\r\n”或“行分隔符”、“段落分隔符”和“下一行”的任何一个\r、\n或unicode字符。
回答by Stephen C
It is not documented (in Java 1.6) but the JDK code uses this regex to match a line break:
它没有记录（在 Java 1.6 中），但 JDK 代码使用此正则表达式来匹配换行符：
"\r\n|[\n\r\u2028\u2029\u0085]"
Here's a link to the source code: http://cr.openjdk.java.net/~briangoetz/7012540/webrev/src/share/classes/java/util/Scanner.java.html
这是源代码的链接：http: //cr.openjdk.java.net/~briangoetz/7012540/webrev/src/share/classes/java/util/Scanner.java.html
IMO, this ought to be specified, since Scanner's behavior wrt to line separators is different to (for example) BufferedReader's. (I've lodged a bug report ...)
海事组织，这应该被指定，因为Scanner' ' 的行分隔符的行为与（例如）BufferedReader的不同。（我已经提交了错误报告...）
