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在一个项目中,我们有这样的文本文件:
mv A, R3
mv R2, B
mv R1, R3
mv B, R4
add A, R1
add B, R1
add R1, R2
add R3, R3
add R21, X
add R12, Y
mv X, R2
我需要根据以下内容替换字符串,但我正在寻找以获得更通用的解决方案。
R1 => R2
R2 => R3
R3 => R1
R12 => R21
R21 => R12
我知道我可以在 Perl 中完成,以下代码中的 replace() 函数,但真正的应用程序是用 Java 编写的,所以解决方案需要在Java中也是如此。
#!/usr/bin/perl
use strict;
use warnings;
use File::Slurp qw(read_file write_file);
my %map = (
R1 => 'R2',
R2 => 'R3',
R3 => 'R1',
R12 => 'R21',
R21 => 'R12',
);
replace(\%map, \@ARGV);
sub replace {
my ($map, $files) = @_;
# Create R12|R21|R1|R2|R3
# making sure R12 is before R1
my $regex = join "|",
sort { length($b) <=> length($a) }
keys %$map;
my $ts = time;
foreach my $file (@$files) {
my $data = read_file($file);
$data =~ s/\b($regex)\b/$map{$1}/g;
rename $file, "$file.$ts"; # backup with current timestamp
write_file( $file, $data);
}
}
非常感谢您对 Java 实现的帮助。
最佳答案
在过去的两周里,我不得不多次使用这种算法。所以这是世界上第二冗长的语言......
import java.util.HashMap;
import java.util.regex.Pattern;
import java.util.regex.Matcher;
/*
R1 => R2
R2 => R3
R3 => R1
R12 => R21
R21 => R12
*/
String inputString
= "mv A, R3\n"
+ "mv R2, B\n"
+ "mv R1, R3\n"
+ "mv B, R4\n"
+ "add A, R1\n"
+ "add B, R1\n"
+ "add R1, R2\n"
+ "add R3, R3\n"
+ "add R21, X\n"
+ "add R12, Y\n"
+ "mv X, R2"
;
System.out.println( "inputString = \"" + inputString + "\"" );
HashMap h = new HashMap();
h.put( "R1", "R2" );
h.put( "R2", "R3" );
h.put( "R3", "R1" );
h.put( "R12", "R21" );
h.put( "R21", "R12" );
Pattern p = Pattern.compile( "\\b(R(?:12?|21?|3))\\b");
Matcher m = p.matcher( inputString );
StringBuffer sbuff = new StringBuffer();
int lastEnd = 0;
while ( m.find()) {
int mstart = m.start();
if ( lastEnd < mstart ) {
sbuff.append( inputString.substring( lastEnd, mstart ));
}
String key = m.group( 1 );
String value = (String)h.get( key );
sbuff.append( value );
lastEnd = m.end();
}
if ( lastEnd < inputString.length() ) {
sbuff.append( inputString.substring( lastEnd ));
}
System.out.println( "sbuff = \"" + sbuff + "\"" );
这可以通过这些类进行 Java 化:
import java.util.Comparator;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeSet;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
interface StringReplacer {
public CharSequence getReplacement( Matcher matcher );
}
class Replacementifier {
static Comparator keyComparator = new Comparator() {
public int compare( Object o1, Object o2 ) {
String s1 = (String)o1;
String s2 = (String)o2;
int diff = s1.length() - s2.length();
return diff != 0 ? diff : s1.compareTo( s2 );
}
};
Map replaceMap = null;
public Replacementifier( Map aMap ) {
if ( aMap != null ) {
setReplacements( aMap );
}
}
public setReplacements( Map aMap ) {
replaceMap = aMap;
}
private static String createKeyExpression( Map m ) {
Set set = new TreeSet( keyComparator );
set.addAll( m.keySet());
Iterator sit = set.iterator();
StringBuffer sb = new StringBuffer( "(" + sit.next());
while ( sit.hasNext()) {
sb.append( "|" ).append( sit.next());
}
sb.append( ")" );
return sb.toString();
}
public String replace( Pattern pattern, CharSequence input, StringReplacer replaceFilter ) {
StringBuffer output = new StringBuffer();
Matcher matcher = pattern.matcher( inputString );
int lastEnd = 0;
while ( matcher.find()) {
int mstart = matcher.start();
if ( lastEnd < mstart ) {
output.append( inputString.substring( lastEnd, mstart ));
}
CharSequence cs = replaceFilter.getReplacement( matcher );
if ( cs != null ) {
output.append( cs );
}
lastEnd = matcher.end();
}
if ( lastEnd < inputString.length() ) {
sbuff.append( inputString.substring( lastEnd ));
}
}
public String replace( Map rMap, CharSequence input ) {
// pre-condition
if ( rMap == null && replaceMap == null ) return input;
Map repMap = rMap != null ? rMap : replaceMap;
Pattern pattern
= Pattern.compile( createKeyExpression( repMap ))
;
StringReplacer replacer = new StringReplacer() {
public CharSequence getReplacement( Matcher matcher ) {
String key = matcher.group( 1 );
return (String)repMap.get( key );
}
};
return replace( pattern, input, replacer );
}
}
关于java - 如何用 Java 替换文本中的字符串?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/381066/
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