java 正则表达式_a-z_0-9 validation_Java Regex Password Validation Example
当今几乎所有应用程序都需要Password validation 。 通过手动编写所有内容以使用第三方可用的API，可以通过多种方法来验证密码。 在此Java regex密码验证教程中 ，我们正在使用regular expressions构建password validator 。
1. Regex for password validation((?=.*[a-z])(?=.*d)(?=.*[@#$%])(?=.*[A-Z]).{6,16})
上面的正则表达式有以下几节：(?=.*[a-z]) : This matches the presence of at least one lowercase letter.
(?=.*d) : This matches the presence of at least one digit i.e. 0-9.
(?=.*[@#$%]) : This matches the presence of at least one special character.
((?=.*[A-Z]) : This matches the presence of at least one capital letter.
{6,16} : This limits the length of password from minimum 6 letters to maximum 16 letters.
前4个部分的顺序可以更改，甚至可以从最终正则表达式中删除。 这个事实可以用来以编程方式构建我们的密码验证器。
2. Java program to validate password using regex
我们正在使验证器可配置，以便可以根据需要设置限制。 就像我们要强制使用至少一个特殊字符而不是任何大写字母一样，我们可以相应地传递所需的参数。package com.howtodoinjava.regex;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class PasswordValidator
{
private static PasswordValidator INSTANCE = new PasswordValidator();
private static String pattern = null;
/**
* No one can make a direct instance
* */
private PasswordValidator()
{
//do nothing
}
/**
* Force the user to build a validator using this way only
* */
public static PasswordValidator buildValidator( boolean forceSpecialChar,
boolean forceCapitalLetter,
boolean forceNumber,
int minLength,
int maxLength)
{
StringBuilder patternBuilder = new StringBuilder("((?=.*[a-z])");
if (forceSpecialChar)
{
patternBuilder.append("(?=.*[@#$%])");
}
if (forceCapitalLetter)
{
patternBuilder.append("(?=.*[A-Z])");
}
if (forceNumber)
{
patternBuilder.append("(?=.*d)");
}
patternBuilder.append(".{" + minLength + "," + maxLength + "})");
pattern = patternBuilder.toString();
return INSTANCE;
}
/**
* Here we will validate the password
* */
public static boolean validatePassword(final String password)
{
Pattern p = Pattern.compile(pattern);
Matcher m = p.matcher(password);
return m.matches();
}
}
3. Unit test password validation
因此，我们的密码验证程序已准备就绪。 让我们用一些JUnit测试用例进行测试。package com.howtodoinjava.regex;
import junit.framework.Assert;
import org.junit.Test;
@SuppressWarnings("static-access")
public class TestPasswordValidator
{
@Test
public void testNormalPassword()
{
PasswordValidator validator = PasswordValidator.buildValidator(false, false, false, 6, 14);
Assert.assertTrue(validator.validatePassword("howtodoinjava"));
Assert.assertTrue(validator.validatePassword("howtodoin"));
//Sort on length
Assert.assertFalse(validator.validatePassword("howto"));
}
@Test
public void testForceNumeric()
{
PasswordValidator validator = PasswordValidator.buildValidator(false,false, true, 6, 16);
//Contains numeric
Assert.assertTrue(validator.validatePassword("howtodoinjava12"));
Assert.assertTrue(validator.validatePassword("34howtodoinjava"));
Assert.assertTrue(validator.validatePassword("howtodo56injava"));
//No numeric
Assert.assertFalse(validator.validatePassword("howtodoinjava"));
}
@Test
public void testForceCapitalLetter()
{
PasswordValidator validator = PasswordValidator.buildValidator(false,true, false, 6, 16);
//Contains capitals
Assert.assertTrue(validator.validatePassword("howtodoinjavA"));
Assert.assertTrue(validator.validatePassword("Howtodoinjava"));
Assert.assertTrue(validator.validatePassword("howtodOInjava"));
//No capital letter
Assert.assertFalse(validator.validatePassword("howtodoinjava"));
}
@Test
public void testForceSpecialCharacter()
{
PasswordValidator validator = PasswordValidator.buildValidator(true,false, false, 6, 16);
//Contains special char
Assert.assertTrue(validator.validatePassword("howtod@injava"));
Assert.assertTrue(validator.validatePassword("@Howtodoinjava"));
Assert.assertTrue(validator.validatePassword("howtodOInjava@"));
//No special char
Assert.assertFalse(validator.validatePassword("howtodoinjava"));
}
}
在这篇文章中，我们学习了使用Java正则表达式进行密码验证的方法，该规则能够验证字母数字和特殊字符，包括最大和最小密码长度。