基于Spring depends-on的使用详解

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。

<?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 depends-on='mother'></bean> <bean class='com.tyyd.lifecallbacks.domain.Mother'></bean></beans>

son这个Bean的产生依赖于mother这个Bean。

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.xsdhttp://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 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 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 depends-on='car' p:name='Tom' p:address-ref='address2' > </bean> <bean 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好吧啦网。