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SpEL expression can be used in Annotation based beans configuration
Syntax
Following is an example of using an expression in annotation based configuration.
@Value("#{ T(java.lang.Math).random() * 100.0 }") private int id;
Here we are using @Value annotation and we”ve specified a SpEL expression on a property. Similarly we can specify SpEL expression on setter methods, on constructors and during autowiring as well.
@Value("#{ systemProperties[''user.country''] }") public void setCountry(String country) { this.country = country; }
Following example shows the various use cases.
Example
Let”s update the project created in Spring SpEL – Create Project chapter. We”re adding/updating following files −
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Employee.java − An employee class.
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AppConfig.java − A configuration class.
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MainApp.java − Main application to run and test.
Here is the content of Employee.java file −
package com.tutorialspoint; import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Component; @Component public class Employee { @Value("#{ T(java.lang.Math).random() * 100.0 }") private int id; private String name; private String country; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } @Value("Mahesh") public void setName(String name) { this.name = name; } public String getCountry() { return country; } @Value("#{ systemProperties[''user.country''] }") public void setCountry(String country) { this.country = country; } @Override public String toString() { return "[" + id + ", " + name + ", " + country + "]"; } }
Here is the content of AppConfig.java file −
package com.tutorialspoint; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; @Configuration @ComponentScan(basePackages = "com.tutorialspoint") public class AppConfig { }
Here is the content of MainApp.java file −
package com.tutorialspoint; import org.springframework.context.annotation.AnnotationConfigApplicationContext; public class MainApp { public static void main(String[] args) { AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(); context.register(AppConfig.class); context.refresh(); Employee emp = context.getBean(Employee.class); System.out.println(emp); } }
Output
[84, Mahesh, IN]
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