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：
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<?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
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<?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> |
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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); }} |
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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; }} |
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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 + "]"; }} |
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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服务器之家。
原文链接：https://blog.csdn.net/qushaming/article/details/102605829
