PHP正则表达式 |
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| 来源：互联网 作者：未知 发布时间：2007-12-08 |
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Regex情景范例
以下代码范例演示了java.util.regex软件包在各种常见情形 下的用法：
简单的单词替换
/*
* This code writes "One dog, two dogs in the yard."
* to the standard-output stream:
*/
import java.util.regex.*;
public class Replacement {
public static void main(String[] args)
throws Exception {
// Create a pattern to match cat
Pattern p = Pattern.compile("cat");
// Create a matcher with an input string
Matcher m = p.matcher("one cat," +
" two cats in the yard");
StringBuffer sb = new StringBuffer();
boolean result = m.find();
// Loop through and create a new String
// with the replacements
while(result) {
m.appendReplacement(sb, "dog");
result = m.find();
}
// Add the last segment of input to
// the new String
m.appendTail(sb);
System.out.println(sb.toString()); php程序员站
}
}
电子邮件确认
以下代码是这样一个例子：你可以检查一些字符是不是一个电子邮件地址。 它并不是一个完整的、适用于所有可能情形的电子邮件确认程序，但是可以在 需要时加上它。
/*
* Checks for invalid characters
* in email addresses
*/
public class EmailValidation {
public static void main(String[] args)
throws Exception {
String input = "@sun.com";
//Checks for email addresses starting with
//inappropriate symbols like dots or @ signs.
Pattern p = Pattern.compile("^\\.|^\\@");
Matcher m = p.matcher(input);
if (m.find())
System.err.println("Email addresses don't start" +
" with dots or @ signs.");
//Checks for email addresses that start with
//www. and prints a message if it does.
p = Pattern.compile("^www\\."); php程序员站
m = p.matcher(input);
if (m.find()) {
System.out.println("Email addresses don't start" +
" with \"www.\", only web pages do.");
}
p = Pattern.compile("[^A-Za-z0-9\\.\\@_\\-~#]+");
m = p.matcher(input);
StringBuffer sb = new StringBuffer();
boolean result = m.find();
boolean deletedIllegalChars = false;
while(result) {
deletedIllegalChars = true;
m.appendReplacement(sb, "");
result = m.find();
}
// Add the last segment of input to the new String
m.appendTail(sb);
input = sb.toString();
if (deletedIllegalChars) {
System.out.println("It contained incorrect characters" +
" , such as spaces or commas.");
}
}
}
从文件中删除控制字符
/* This class removes control characters from a named
* file.
*/
import java.util.regex.*; www.phperz.com
import java.io.*;
public class Control {
public static void main(String[] args)
throws Exception {
//Create a file object with the file name
//in the argument:
File fin = new File("fileName1");
File fout = new File("fileName2");
//Open and input and output stream
FileInputStream fis =
new FileInputStream(fin);
FileOutputStream fos =
new FileOutputStream(fout);
BufferedReader in = new BufferedReader(
new InputStreamReader(fis));
BufferedWriter out = new BufferedWriter(
new OutputStreamWriter(fos));
// The pattern matches control characters
Pattern p = Pattern.compile("{cntrl}");
Matcher m = p.matcher("");
String aLine = null; phperz.com
while((aLine = in.readLine()) != null) {
m.reset(aLine);
//Replaces control characters with an empty
//string.
String result = m.replaceAll("");
out.write(result);
out.newLine();
}
in.close();
out.close();
}
}
文件查找
/*
* Prints out the comments found in a .java file.
*/
import java.util.regex.*;
import java.io.*;
import java.nio.*;
import java.nio.charset.*;
import java.nio.channels.*;
public class CharBufferExample {
public static void main(String[] args) throws Exception {
// Create a pattern to match comments
Pattern p =
Pattern.compile("//.*$", Pattern.MULTILINE);
// Get a Channel for the source file
File f = new File("Replacement.java");
FileInputStream fis = new FileInputStream(f);
FileChannel fc = fis.getChannel();
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