Spring expression language (SpEL) allow developer uses expression to execute method and inject the method returned value into property, or so called “SpEL method invocation“.

Spring EL in Annotation

See how to do Spring EL method invocation with @Value annotation.

package com.mkyong.core;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("customerBean")
public class Customer { 
    @Value("#{'mkyong'.toUpperCase()}") 
    private String name; 
    @Value("#{priceBean.getSpecialPrice()}") 
    private double amount; 
    public String getName() { 
        return name; 
    } 
    public void setName(String name) { 
        this.name = name; 
    } 
    public double getAmount() { 
        return amount; 
    } 
    public void setAmount(double amount) { 
        this.amount = amount;  
    } 
    @Override 
    public String toString() { 
        return "Customer [name=" + name + ", amount=" + amount + "]"; 
    }
}

package com.mkyong.core;
import org.springframework.stereotype.Component;

@Component("priceBean")
public class Price { 
    public double getSpecialPrice() { 
        return new Double(99.99); 
    }
}

Output

Customer [name=MKYONG, amount=99.99]

Explanation

Call the ‘toUpperCase()‘ method on the string literal.

@Value("#{'mkyong'.toUpperCase()}") 
private String name;

Call the ‘getSpecialPrice()‘ method on bean ‘priceBean‘.

@Value("#{priceBean.getSpecialPrice()}") 
private double amount;

Spring EL in XML

This is the equivalent version in bean definition XML file.

<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-3.0.xsd"> 
    <bean id="customerBean" class="com.mkyong.core.Customer"> 
        <property name="name" value="#{'mkyong'.toUpperCase()}" /> 
        <property name="amount" value="#{priceBean.getSpecialPrice()}" /> 
    </bean> 
    <bean id="priceBean" class="com.mkyong.core.Price" /> 
</beans>

Output

Customer [name=MKYONG, amount=99.99]