Admin: 1 версия

2010-06-01T06:00:52Z

1 версия

в 18:01, 31 мая 2010

2010-05-31T18:01:43Z

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== Apply Regular Expressions on the contents of a file ==



<source lang="java">

import java.io.FileInputStream;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
public static void main(String[] argv) throws Exception {
Pattern pattern = Pattern.rupile("pattern");
FileInputStream input = new FileInputStream("file.txt");
FileChannel channel = input.getChannel();
ByteBuffer bbuf = channel.map(FileChannel.MapMode.READ_ONLY, 0, (int) channel.size());
CharBuffer cbuf = Charset.forName("8859_1").newDecoder().decode(bbuf);
Matcher matcher = pattern.matcher(cbuf);
while (matcher.find()) {
String match = matcher.group();
System.out.println(match);
}
}
}
</source>



== Reading Lines from a String Using a Regular Expression ==



<source lang="java">

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
public static void main(String[] argv) throws Exception {
CharSequence inputStr = "a\rb";
inputStr = "a\r\nb";
inputStr = "a\nb";
String patternStr = "^(.*)$";
Pattern pattern = Pattern.rupile(patternStr, Pattern.MULTILINE);
Matcher matcher = pattern.matcher(inputStr);
while (matcher.find()) {
String lineWithTerminator = matcher.group(0);
String lineWithoutTerminator = matcher.group(1);
}
}
}
</source>



== Use FileChannels and ByteBuffers to Store Patterns ==



<source lang="java">
//Example File
/*
#Email validator that adheres directly to the specification
#for email address naming. It allows for everything from
#ipaddress and country-code domains to very rare characters
#in the username.
email=^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-
9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-
9]{1,3})(\]?)$
#Matches UK postcodes according to the following rules 1. LN NLL
#eg N1 1AA 2. LLN NLL eg SW4 0QL 3. LNN NLL eg M23 4PJ 4. LLNN NLL
#eg WS14 0JT 5. LLNL NLL eg SW1N 4TB 6. LNL NLL eg W1C 8LQ Thanks
#to Simon Bell for informin ...
zip=^[a-zA-Z]{1,2}[0-9][0-9A-Za-z]{0,1} {0,1}[0-9][A-Za-z]{2}$
#This regular expression matches dates of the form XX/XX/YYYY
#where XX can be 1 or 2 digits long and YYYY is always 4
#digits long.
dates=^\d{1,2}\/\d{1,2}\/\d{4}$
*/
import java.util.Properties;
import java.util.regex.*;
import java.util.*;
import java.io.*;
import java.nio.*;
import java.nio.channels.*;
import java.util.logging.Logger;
public class RegexProperties extends Properties {
private static Logger log = Logger.getAnonymousLogger();
public void load(String inStream) throws IOException,
PatternSyntaxException {
load(new FileInputStream(inStream));
}
public void load(FileInputStream inStream) throws IOException,
PatternSyntaxException {
FileChannel fc = inStream.getChannel();
ByteBuffer bb = ByteBuffer.allocate((int) fc.size());
fc.read(bb);
bb.flip();
String fileContent = new String(bb.array());
Pattern pattern = Pattern.rupile("^(.*)$", Pattern.MULTILINE);
Matcher matcher = pattern.matcher(fileContent);
while (matcher.find()) {
String line = matcher.group(1);
if (line != null && !"".equals(line.trim())
&& !line.startsWith("#") && !line.startsWith("!")) {
String keyValue[] = null;
if (line.indexOf("=") > 0)
keyValue = line.split("=", 2);
else
keyValue = line.split(":", 2);
if (keyValue != null) {
super.put(keyValue[0].trim(), keyValue[1]);
}
}
}
fc = null;
bb = null;
}
public void store(FileOutputStream out, String header)
throws UnsupportedOperationException {
throw new UnsupportedOperationException("unsupported for this class");
}
public void putAll(Map t) {
throw new UnsupportedOperationException("unsupported for this class");
}
}

</source>



== Using a Regular Expression to Filter Lines from a Reader ==



<source lang="java">

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
public static void main(String[] argv) throws Exception {
String filename = "infile.txt";
String patternStr = "pattern";
BufferedReader rd = new BufferedReader(new FileReader(filename));
Pattern pattern = Pattern.rupile(patternStr);
Matcher matcher = pattern.matcher("\\D");
String line = null;
while ((line = rd.readLine()) != null) {
matcher.reset(line);
if (matcher.find()) {
// line matches the pattern
}
}
}
}
</source>

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Admin: 1 версия

в 18:01, 31 мая 2010