Spring学习——AutoWire自动注入

- 日理万妓 2022-05-13 01:10 229阅读 0赞

**在原先的配置文件中，A需要注入B  [GitHub上springAutoWire的demo][GitHub_springAutoWire_demo]**

private B b;

我们需要在每个<bean name="A">标签中手动添加注入对象B或属性或方法

<bean name="" class="" **autowire**="">  
**autowire**自动注入，无需我们手动添加配置

1>autowire="byName" 通过A中调用B的名字来查找xml中是否有<bean name="b" >并与之匹配连接注入

2>autowire="byType" 通过A中调用B的类型来查找xml中是否有<bean name="B" >并与之匹配连接注入

3>autowire="constructor" 通过A中构造函数的参数(B b,String str)来查找xml中是否有<bean name="B" >并与之匹配连接注入

A.java

package com.spring.autowire.demo;
    
    public class A {
    	private B b;
    	private String str;
    	
    	public A(){
    		
    	}
    	public A(B b,String str){
    		this.b=b;
    		this.str=str;
    	}
    	
    	public B getB() {
    		return b;
    	}
    	public void setB(B b) {
    		this.b = b;
    	}
    	public String getStr() {
    		return str;
    	}
    	public void setStr(String str) {
    		this.str = str;
    	}
    	
    	
    }

B.java

package com.spring.autowire.demo;
    
    public class B {
    	public B(){
    		System.out.println("B的构造函数被调用");
    	}
    	
    	public void bSpeack(){
    		System.out.println("B说话");
    	}
    }

SpringMain.java

package com.spring.autowire.demo;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    public class SpringMain {
    	public static void main(String[] args){
    		System.out.println("------自动注入byName----------");
    		ApplicationContext  context1 = new ClassPathXmlApplicationContext("Beans1.xml");
    		A a1 = (A) context1.getBean("A");
    		System.out.println(a1.getStr());
    		
    		System.out.println("------自动注入byType----------");
    		ApplicationContext  context2 = new ClassPathXmlApplicationContext("Beans2.xml");
    		A a2 = (A) context2.getBean("A");
    		System.out.println(a2.getStr());
    		
    		System.out.println("------自动注入构造函数----------");
    		ApplicationContext  context3 = new ClassPathXmlApplicationContext("Beans3.xml");
    		A a3 = (A) context3.getBean("A");
    		System.out.println(a3.getStr());
    		
    	}
    }

[GitHub_springAutoWire_demo]: https://github.com/2637977081/Spring/tree/master/workspace/SpringAutoWire