Spring EL hello world example
The Spring EL is similar with OGNL and JSF EL, and evaluated or executed during the bean creation time. In addition, all Spring expressions are available via XML or annotation.
In this tutorial, we show you how to use Spring Expression Language(SpEL), to inject String, integer and bean into property, both in XML and annotation.
1. Spring EL Dependency
Declares the core Spring jars in Maven pom.xml
file, it will download the Spring EL dependencies automatically.
File : pom.xml
<properties>
<spring.version>3.0.5.RELEASE</spring.version>
</properties>
<dependencies>
<!-- Spring 3 dependencies -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependencies>
2. Spring Beans
Two simple beans, later use SpEL to inject values into property, in XML and annotation.
package com.mkyong.core;
public class Customer {
private Item item;
private String itemName;
}
package com.mkyong.core;
public class Item {
private String name;
private int qty;
}
3. Spring EL in XML
The SpEL are enclosed with #{ SpEL expression }
, see following example in XML bean definition 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="itemBean" class="com.mkyong.core.Item">
<property name="name" value="itemA" />
<property name="qty" value="10" />
</bean>
<bean id="customerBean" class="com.mkyong.core.Customer">
<property name="item" value="#{itemBean}" />
<property name="itemName" value="#{itemBean.name}" />
</bean>
</beans>
- #{itemBean} – inject “itemBean” into “customerBean” bean’s “item” property.
- #{itemBean.name} – inject “itemBean”‘s “name” property into “customerBean” bean’s “itemName” property.
4. Spring EL in Annotation
See equivalent version in annotation mode.
To use SpEL in annotation, you must register your component via annotation. If you register your bean in XML and define
@Value
in Java class, the @Value
will failed to execute.
package com.mkyong.core;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component("customerBean")
public class Customer {
@Value("#{itemBean}")
private Item item;
@Value("#{itemBean.name}")
private String itemName;
//...
}
package com.mkyong.core;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component("itemBean")
public class Item {
@Value("itemA") //inject String directly
private String name;
@Value("10") //inject interger directly
private int qty;
public String getName() {
return name;
}
//...
}
Enable auto component scanning.
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<context:component-scan base-package="com.mkyong.core" />
</beans>
In annotation mode, you use @Value
to define Spring EL. In this case, you inject a String and Integer value directly into the “itemBean“, and later inject the “itemBean” into “customerBean” property.
5. Output
Run it, both SpEL in XML and annotation are display the same result :
package com.mkyong.core;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class App {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("SpringBeans.xml");
Customer obj = (Customer) context.getBean("customerBean");
System.out.println(obj);
}
}
Output
Customer [item=Item [name=itemA, qty=10], itemName=itemA]
Can some one please let me know how to access ArrayList of Arraylist using spring Expression Language?
I have Pojo that has a Arraylist of Customer POJO which in turn has a ArrayList of Address POJO.
I tried using the ‘Projection’ operator and tried something like Customers.![Addresses.![addressFirstLine]]
but getting error. Help appreciated
hi i am getting this error can pls help me any one
Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 5): Field or property ‘name’ cannot be found on object of type ‘beans.Item’
I can’t seem to get this to work. Question: Does spel not require the spring-expression maven dependency? I havent tried that yet, but wondering if that’s why it’s not working for me.
Concise and simple 🙂
Thanks
Setters and getter methods for Item and customer are required to make it work.
Also the toString method for Customer is also needed for getting desired result.
How do i implement this in a spring batch… i tried this but since its standalone its not working.. please help
Extremely helpful, Me and my collegues are regular users of your site. Keep up the good work.
Custom .toString methods are required to produce the output listed in the example. Perhaps that is implied or I missed something.
for Customer.java:
@Override
public String toString() {
return String.format(“Customer [item=%s, itemName=%s]”,item.toString(), getItemName());
}
for Item.java:
@Override
public String toString() {
return String.format(“Item [name=%s, qty=%d]”, getName(), getQty());
}
I meant to ask
is the same as
Right?
is the same result as
right?
can we use spring expression language in jsp like #{object.property}
remember object already present in context factory
Could you please let me know how to set values in collections like List,Set,Map using this @Value annotation?
why did you use in the annotation equivalent example @component rather than @bean ? and what’s the difference between the two annotaions ?
This link answer your question;
http://stackoverflow.com/questions/10604298/spring-component-versus-bean