16 Spring EL bean引用实例

在Spring EL，可以使用点(.)符号嵌套属性参考一个bean。例如，“bean.property_name”。

public class Customer {
    
    @Value("#{addressBean.country}")
    private String country;

在上面的代码片段，它从“addressBean” bean注入了“country”属性到现在的“customer”类的“country”属性的值。

Spring EL以注解的形式

请参阅下面的例子，演示如何使用使用 SpEL 引用一个bean，bean属性也它的方法。

package com.gp6.el.bean;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("addressBean")
public class Address {
    @Value("哈哈,呵呵")
    private String street;

    @Value("666666")
    private int postcode;

    @Value("CN")
    private String country;

    public String getFullAddress(String prefix) {

        return prefix + " : " + street + " " + postcode + " " + country;
    }

    @Override
    public String toString() {
        return "Address [street=" + street + ", postcode=" + postcode
                + ", country=" + country + "]";
    }

    public String getStreet() {
        return street;
    }


    public void setStreet(String street) {
        this.street = street;
    }


    public int getPostcode() {
        return postcode;
    }


    public void setPostcode(int postcode) {
        this.postcode = postcode;
    }


    public String getCountry() {
        return country;
    }
    
    public void setCountry(String country) {
        this.country = country;
    }

}

package com.gp6.el.bean;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("customerBean")
public class Customer {

    @Value("#{addressBean}")
    private Address address;

    @Value("#{addressBean.country}")
    private String country;
    
    @Value("#{addressBean.getFullAddress('小伙')}")
    private String fullAddress;

    @Override
    public String toString() {
        return "Customer [address=" + address + "\n, country=" + country
                + "\n, fullAddress=" + fullAddress + "]";
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    public String getFullAddress() {
        return fullAddress;
    }

    public void setFullAddress(String fullAddress) {
        this.fullAddress = fullAddress;
    }
}

配置文件

<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.gp6.el.bean" />

</beans>

测试文件

package com.gp6.el.bean;

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

public class Test {

     public static void main( String[] args ) {
            
         ApplicationContext context = new ClassPathXmlApplicationContext(
                    "com/gp6/el/bean/el_bean.xml");

         Customer customer = (Customer) context.getBean("customerBean");
         System.out.println(customer);
    }
    
}

输出结果

Customer [address=Address [street=哈哈,呵呵, postcode=666666, country=CN]
, country=CN
, fullAddress=小伙 : 哈哈,呵呵 666666 CN]

- 用xml文件配置可达到相同效果,具体配置参考上一篇文章