In this Spring Expression Language example we are going to learn how to use regular expression or regex to check if a text matches a certain pattern. Spring EL support regular expression using the matches operator.

The matches operator will check if the value has a pattern defined by the regex string, and it returns the evaluation result as a boolean value true if the text matches the regex or false if otherwise.

For example, we can use the matches operator to check if the given email address is a valid email address. As can be seen in the following example:

<property name="emailValid" 
          value="#{user.email matches '^[_A-Za-z0-9-]+(.[_A-Za-z0-9-]+)*@[A-Za-z0-9]+(.[A-Za-z0-9]+)*(.[A-Za-z]{2,})$'}"/>

This configuration will evaluate the user.email property to check if the email pattern matches with the given regular expression. If matches then the emailValid property will be set to true otherwise it will be false.

Let’s see the complete example. Here are the spring configuration file, the User bean and a simple class for running the configuration file.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="user" class="org.kodejava.spring.core.el.User">
        <constructor-arg name="email" value="kodejava@gmail.com" />
        <property name="emailValid"
                  value="#{user.email matches '^[_A-Za-z0-9-]+(.[_A-Za-z0-9-]+)*@[A-Za-z0-9]+(.[A-Za-z0-9]+)*(.[A-Za-z]{2,})$'}" />
    </bean>

    <bean id="user2" class="org.kodejava.spring.core.el.User">
        <constructor-arg name="email" value="kodejava.at.gmail.dot.com" />
        <property name="emailValid"
                  value="#{user2.email matches '^[_A-Za-z0-9-]+(.[_A-Za-z0-9-]+)*@[A-Za-z0-9]+(.[A-Za-z0-9]+)*(.[A-Za-z]{2,})$'}" />
    </bean>

</beans>

The User bean is a simple pojo with two properties, a string email property and a boolean validEmail property.

package org.kodejava.spring.core.el;

public class User {
    private String email;
    private boolean emailValid;

    public User() {
    }

    public User(String email) {
        this.email = email;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public boolean isEmailValid() {
        return emailValid;
    }

    public void setEmailValid(boolean emailValid) {
        this.emailValid = emailValid;
    }
}

And finally the application class.

package org.kodejava.spring.core.el;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpELRegexExample {
    public static void main(String[] args) {
        try (ClassPathXmlApplicationContext context =
                     new ClassPathXmlApplicationContext("spel-regex.xml")) {

            User user = (User) context.getBean("user");
            System.out.println("user.getEmail()     = " + user.getEmail());
            System.out.println("user.isEmailValid() = " + user.isEmailValid());

            User user2 = (User) context.getBean("user2");
            System.out.println("user.getEmail()     = " + user2.getEmail());
            System.out.println("user.isEmailValid() = " + user2.isEmailValid());
        }
    }
}

When we run the code we will obtain the following result:

user.getEmail()     = kodejava@gmail.com
user.isEmailValid() = true
user.getEmail()     = kodejava.at.gmail.dot.com
user.isEmailValid() = false

Maven Dependencies

<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>5.3.23</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>5.3.23</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
        <version>5.3.23</version>
    </dependency>
</dependencies>