escape.html
来自「java类库详细讲解」· HTML 代码 · 共 167 行
HTML
167 行
<HTML>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<TITLE>Escaping Special Characters in a Pattern
(Java Developers Almanac Example)
</TITLE>
<META CONTENT="Patrick Chan" NAME="AUTHOR">
<META CONTENT="Code Examples from The Java Developers Almanac 1.4" NAME="DESCRIPTION">
<META CONTENT="Addison-Wesley/Patrick Chan" NAME="OWNER">
<META CONTENT="3/20/02" NAME="revision">
<STYLE TYPE="text/css">
<!-- BODY CODE {font-family: Courier, Monospace; font-size: 11pt} TABLE, BODY {font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 10pt} PRE {font-family: Courier, Monospace; font-size: 10pt} H3 {font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 11pt} A.eglink {text-decoration: none} A:hover.eglink {text-decoration: underline} -->
</STYLE>
</HEAD>
<BODY>
<TABLE CELLSPACING="0" CELLPADDING="0" BORDER="0">
<TR>
<TD rowspan="3"><A HREF="/?l=ex"><IMG BORDER="0" ALIGN="BOTTOM" HSPACE="10" SRC="/egs/almanac14a.jpg"></A></TD><TD VALIGN="top"><font face="Times" size="6"><b>The Java Developers Almanac 1.4</b></font>
<br>
Order this book from <a href="/cgi-bin/scripts/redirect.pl?l=ex&url=http://www.amazon.com/exec/obidos/ASIN/0201752808/xeo">Amazon</a>.
</TD>
</TR>
<TR>
<TD align="right" valign="bottom">
<FORM method="get" action="/cgi-bin/search/find.pl">
<INPUT size="25" name="words" type="text"><INPUT value="Search" type="submit">
</FORM>
</TD>
</TR>
</TABLE>
<HR color="#6666cc">
<DIV ALIGN="LEFT">
<A HREF="/">Home</A>
>
<A HREF="../index.html">List of Packages</A>
>
<B><A HREF="../java.util.regex/pkg.html">java.util.regex</A></B><font color="#666666" SIZE="-2">
[26 examples]
</font>
</DIV><P>
<h3>
e428.
Escaping Special Characters in a Pattern</h3>
Any nonalphanumeric character can be escaped with a backslash to
remove it's special meaning (if any). This example implements a
method that escapes all nonalphanumeric characters. This method is
useful when the pattern is retrieved programmatically and
it is necessary to search for the pattern literally.
<P> Another method of escaping the characters in a pattern is to
surround the pattern with <code>\Q</code> and <code>\E</code>. The only thing to watch out for
is the presence of <code>\E</code> in the pattern, which would end the escaping of
the pattern.
<pre>
String patternStr = <font color="#0066ff"><i>"i.e."</i></font>;
boolean matchFound = Pattern.matches(patternStr, <font color="#0066ff"><i>"i.e."</i></font>);// true
matchFound = Pattern.matches(patternStr, <font color="#0066ff"><i>"ibex"</i></font>); // true
// Quote the pattern; i.e. surround with \Q and \E
matchFound = Pattern.matches("\\Q"+patternStr+"\\E", <font color="#0066ff"><i>"i.e."</i></font>); // true
matchFound = Pattern.matches("\\Q"+patternStr+"\\E", <font color="#0066ff"><i>"ibex"</i></font>); // false
// Escape the pattern
patternStr = escapeRE(patternStr); // i\.e\.
matchFound = Pattern.matches(patternStr, <font color="#0066ff"><i>"i.e."</i></font>); // true
matchFound = Pattern.matches(patternStr, <font color="#0066ff"><i>"ibex"</i></font>); // false
// Returns a pattern where all punctuation characters are escaped.
static Pattern escaper = Pattern.compile("([^a-zA-z0-9])");
public static String escapeRE(String str) {
return escaper.matcher(str).replaceAll("\\\\$1");
}
</pre>
<P><table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
<tr>
<td bgcolor="#6666cc" align="center"><font color="#ffffff">
Related Examples
</font></td>
</tr>
</table>
e423. <a class="eglink" href="BasicMatch.html?l=rel">
Quintessential Regular Expression Search Program
</a>
<br>
e424. <a class="eglink" href="MatchExactly.html?l=rel">
Determining If a String Matches a Pattern Exactly
</a>
<br>
e425. <a class="eglink" href="FromFile.html?l=rel">
Applying Regular Expressions on the Contents of a File
</a>
<br>
e426. <a class="eglink" href="RemDupSpace.html?l=rel">
Removing Duplicate Whitespace in a String
</a>
<br>
e427. <a class="eglink" href="Greedy.html?l=rel">
Greedy and Nongreedy Matching in a Regular Expression
</a>
<br>
<table width="600" CELLSPACING="0" CELLPADDING="2" BORDER="0">
<tr>
<td align="left">
<br>
See also:
<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Flags">
Flags
</a>
<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Groups">
Groups
</a>
<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Lines">
Lines
</a>
<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Paragraphs">
Paragraphs
</a>
<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Searching%20and%20Replacing">
Searching and Replacing
</a>
<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Tokenizing">
Tokenizing
</a>
</td>
</tr>
</table>
<br>
<br>
<FONT FACE="Verdana, Arial, Helvetica, sans-serif" SIZE="0">
© 2002 Addison-Wesley.
</FONT>
</BODY>
</HTML>
⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?