我可以在 java MessageFormat 中转义大括号吗？
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Can I escape braces in a java MessageFormat?
提问by Steve Bosman
I want to output some braces in a java MessageFormat. For example I know the following does not work:
我想在 java MessageFormat 中输出一些大括号。例如，我知道以下不起作用：
MessageFormat.format(" public {0} get{1}() {return {2};}\n\n", type, upperCamel, lowerCamel);
Is there a way of escaping the braces surrounding "return {2}"?
有没有办法转义围绕“return {2}”的大括号？
采纳答案by Brian Agnew
回答by Jon Skeet
Use single quotes:
使用单引号：
MessageFormat.format(" public {0} get{1}() '{'return {2};'}'\n\n",
type, upperCamel, lowerCamel);
If you want to actually usea single quote, just double it. The JavaDoc for MessageFormatgives this somewhat complicated example:
如果您想实际使用单引号，只需将其加倍即可。在对JavaDoc中MessageFormat给出了这样的有些复杂例子：
Thus, a string that should result in the formatted message
"'{0}'"can be written as"'''{'0}''" or "'''{0}'''".
因此，应该导致格式化消息的字符串
"'{0}'"可以写为"'''{'0}''" or "'''{0}'''".
This is ''for a single quote, then '{'for an escaped brace, then 0, '}'for the closing brace and ''for the closing quote.
这是''一个单引号，然后'{'进行转义括号，然后0，'}'在右括号，并''在右引号。
回答by Bombe
Wow. Surprise! The documentation for MessageFormatknows the answer:
哇。惊喜！MessageFormat的文档知道答案：
Within a String,
"''"represents a single quote. A QuotedStringcan contain arbitrary characters except single quotes; the surrounding single quotes are removed. An UnquotedStringcan contain arbitrary characters except single quotes and left curly brackets. Thus, a string that should result in the formatted message"'{0}'"can be written as"'''{'0}''"or"'''{0}'''".
在String 中，
"''"代表单引号。甲QuotedString可以包含除单引号的任意字符; 周围的单引号被删除。一个UnquotedString可以包含除单引号和左大括号的任意字符。因此，应该导致格式化消息的字符串"'{0}'"可以写为"'''{'0}''"或"'''{0}'''"。
回答by Victor Rodriguez
System.out.println(MessageFormat.format("I want to see ticks and curly braces around '''{'{0}'}'''", "this"));
回答by Andreas Heissenberger
you can use this regex with perl or any other language to escape curly brackets and single quotes (x27). It does not touch any placeholder e.g. {0}:
您可以将此正则表达式与 perl 或任何其他语言一起使用来转义大括号和单引号 (x27)。它不会触及任何占位符，例如{0}：
echo "# 'single' quote test \n\n public {0} get{1}() {return {2};}\n\n" | perl -pe 's/\x27/\x27\x27/g; s/\{([^0-9])/\x27\{\x27/g; s/([^0-9])\}/\x27\}\x27/g'
