Spring 中的SpEL

最新推荐文章于 2025-03-05 22:09:14 发布

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本文通过具体示例展示了如何在Spring框架中使用SPEL表达式来设置Bean的属性值。示例包括Address、Car及Person类的定义，并通过Spring上下文加载这些Bean，展示如何动态地设置和获取Bean的属性。

1. 项目结构

Address.java

public class Address {
	
	private String city;
	private String street;
   下面省略了getter 和setter....
}

Car.java

public class Car {
	private String brand;
	private double price;

	private double tyrePerimeter;
	   下面省略了getter 和setter....
}

Person.java

public class Person {
	
	private String name;
	private int age;
	
	private Car car;
	//引用Address  bean 的 city属性
	private String city ;
	//根据car 的price 确定info ：car的price >=500000:豪车 ，否则为：普通车
	private String info ;
	
	   下面省略了getter 和setter....
}

3. 测试：

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestSpringSPEL {
	
	public static void main(String[] args) {
		
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans_spel.xml");
		
		Address address = (Address) applicationContext.getBean("address");
		System.out.println(address);
		
		Car car = (Car) applicationContext.getBean("car");
		System.out.println(car);

		Person person = (Person) applicationContext.getBean("person");
		System.out.println(person);
	}

4. 运行结果：

Address [city=ShangHai, street=NanJingRoad]
Car [brand=BMW, price=1500000.0, tyrePerimeter=251.32741228718345]
Person [name=Tom, age=25, car=Car [brand=BMW, price=1500000.0, tyrePerimeter=251.32741228718345], city=ShangHai, info=豪车]