基于Spring depends-on的使用详解
作者：王哲晓
这篇文章主要介绍了Spring depends-on的使用，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教
Spring depends-on的使用
通过在XML中的<bean>里配置depends-on属性或者在一个类上使用注解@DependsOn，可以使一个Bean的产生依赖于其他几个Bean。
请看如下代码：
<?xml version="1.0" encoding="UTF-8"?>
<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.xsd">
<bean id="son" class="com.tyyd.lifecallbacks.domain.Son" depends-on="mother"></bean>
<bean id="mother" class="com.tyyd.lifecallbacks.domain.Mother"></bean>
</beans>
son这个Bean的产生依赖于mother这个Bean。
Spring Depends-On 不起作用
beans-realation.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd">
<!-- abstract="true" 则不能获得这个bean 说明它只是一个模板，只能被继承 -->
<bean id = "address" class="com.yuxishua.autowire.Address" p:city="Beijing" p:street="ChangAnLu" abstract="true">
</bean>
<!-- 继承bean的配置使用parent 属性，但是没有java 继承的意思 -->
<bean id = "address2" parent="address" p:street="HanSenLU">
</bean>
<!-- 要求person bean 必须有一个关联的car ,意思就是说这个bean依赖car这个bean -->
<bean id = "person" depends-on="car" class="com.yuxishua.autowire.Person" p:name="Tom" p:address-ref="address2" >
</bean>
<bean id = "car" class="com.yuxishua.autowire.Car" p:brand="AuDi" p:price="30000">
</bean>
</beans>
package com.yuxishua.beansrelation;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.yuxishua.autowire.Address;
import com.yuxishua.autowire.Car;
import com.yuxishua.autowire.Person;
public class Main
{
public static void main(String[] args)
{
ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-realation.xml");
Person person = (Person) ctx.getBean("person");
Address address2 = (Address) ctx.getBean("address2");
Car car = (Car) ctx.getBean("car");
System.out.println(address2 );
System.out.println(person);
System.out.println(car);
}
}
package com.yuxishua.autowire;
public class Person
{
private String name;
private Address address;
private Car car;
@Override
public String toString()
{
return "Person [name=" + name + ", address=" + address + ", car=" + car
+ "]";
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public Address getAddress()
{
return address;
}
public void setAddress(Address address)
{
this.address = address;
}
public Car getCar()
{
return car;
}
public void setCar(Car car)
{
this.car = car;
}
}
package com.yuxishua.autowire;
public class Car
{
private String brand;
private double price;
public String getBrand()
{
return brand;
}
public void setBrand(String brand)
{
this.brand = brand;
}
public double getPrice()
{
return price;
}
public void setPrice(double price)
{
this.price = price;
}
@Override
public String toString()
{
return "Car [brand=" + brand + ", price=" + price + "]";
}
}
package com.yuxishua.autowire;
public class Address
{
private String city;
private String street;
@Override
public String toString()
{
return "Address [city=" + city + ", street=" + street + "]";
}
public String getCity()
{
return city;
}
public void setCity(String city)
{
this.city = city;
}
public String getStreet()
{
return street;
}
public void setStreet(String street)
{
this.street = street;
}
}
就上面的代码，结果输出
Person [name=Tom, address=Address [city=Beijing, street=HanSenLU], car=null]
car 为什么没有注入呢，是spring版本的问题吗？还是什么原因？
spring为4.0.8
以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。