引言：
在Spring IOC容器中配置Bean，然后使用该Bean
Car.java
package com.yczlab.spring.beans;
public class Car {
private String brand;
private String corp;
private double price;
private int maxSpeed;
public Car(String brand, String corp, double price) {
super();
this.brand = brand;
this.corp = corp;
this.price = price;
}
public Car(String brand, String corp, int maxSpeed) {
this.brand = brand;
this.corp = corp;
this.maxSpeed = maxSpeed;
}
public String getBrand() {
return brand;
}
public void setBrand(String brand) {
this.brand = brand;
}
public String getCorp() {
return corp;
}
public void setCorp(String corp) {
this.corp = corp;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public int getMaxSpeed() {
return maxSpeed;
}
public void setMaxSpeed(int maxSpeed) {
this.maxSpeed = maxSpeed;
}
@Override
public String toString() {
return "Car{" +
"brand='" + brand + '\'' +
", corp='" + corp + '\'' +
", price=" + price +
", maxSpeed=" + maxSpeed +
'}';
}
}Person.java
package com.yczlab.spring.beans;
public class Person {
private String name;
private int age;
private Car car;
public Person() {
}
public Person(String name, int age, Car car) {
this.name = name;
this.age = age;
this.car = car;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Car getCar() {
return car;
}
public void setCar(Car car) {
this.car = car;
}
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", age=" + age +
", car=" + car +
'}';
}
}HelloWorld.java
package com.yczlab.spring.beans;
public class HelloWorld {
private String name;
public HelloWorld() {
System.out.println("HelloWorld's Constructor...");
}
public HelloWorld(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
System.out.println("setName: " + name);
this.name = name;
}
public void hello() {
System.out.println("hello: " + name);
}
}Main.java
package com.yczlab.spring.beans;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
/*
HelloWorld helloWorld = new HelloWorld();
helloWorld.setName("yczlab");
helloWorld.hello();
*/
//1、创建Spring的IOC容器对象
//ApplicationContext(接口) 代表IOC
//ClassPathXmlApplicationContext 是ApplicationContext接口的实现类，从类路径下加载配置文件夹
ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
//2、从IOC容器中获取Bean实例
//利用id定位到IOC容器中的bean
HelloWorld helloWorld = (HelloWorld)ctx.getBean("helloWorld");
//利用类型放回IOC容器中的Bean，但要求IOC容器中必须只能有一个该类型的Bean
//HelloWorld helloWorld = (HelloWorld) ctx.getBean(HelloWorld.class);
//3、调用hello方法
helloWorld.hello();
System.out.println("************************");
Car car = (Car) ctx.getBean("car");
System.out.println(car);
car = (Car) ctx.getBean("car2");
System.out.println(car);
System.out.println("************************");
Person person = (Person) ctx.getBean("person");
System.out.println(person);
person = (Person) ctx.getBean("person2");
System.out.println(person);
}
}applicationContext.xml配置文件（src/路径下）
<?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">
<!--
配置bean：
class：bean的全类名，通过反射的方式在IOC容器中创建Bean，所以要求Bean中必须有无参的构造器
id：标识容器中的bean，di是唯一的。
-->
<bean id="helloWorld2" class="com.yczlab.spring.beans.HelloWorld">
<property name="name" value="yczlab"></property>
</bean>
<bean id="helloWorld" class="com.yczlab.spring.beans.HelloWorld">
<property name="name" value="yczlab"></property>
</bean>
<!--通过构造方法来配置bean的属性-->
<bean id="car" class="com.yczlab.spring.beans.Car">
<constructor-arg value="Audi" index="0"></constructor-arg>
<constructor-arg value="ShangHai" index="1"></constructor-arg>
<constructor-arg value="300000" index="2" type="double"></constructor-arg>
</bean>
<!--使用构造器注入属性值可以指定参数的位置和参数的类型！以区分重载的构造器-->
<bean id="car2" class="com.yczlab.spring.beans.Car">
<constructor-arg value="Baoma" type="java.lang.String"></constructor-arg>
<!--属性值也可以使用value子节点进行配置-->
<constructor-arg type="java.lang.String">
<value>ShanHai^</value>
</constructor-arg>
<constructor-arg type="int">
<value>250</value>
</constructor-arg>
</bean>
<bean id="person" class="com.yczlab.spring.beans.Person">
<property name="name" value="Tom"></property>
<property name="age" value="24"></property>
<!--可以使用property的ref属性或ref建立bean之间的引用关系-->
<!-- <property name="car" ref="car2"></property> -->
<!--
<property name="car">
<ref bean="car2"></ref>
</property>
-->
<!--也可以使用内部bean，内部bean不能被外部使用，只能在内部使用，所以id属性没必要-->
<property name="car">
<bean class="com.yczlab.spring.beans.Car">
<constructor-arg value="Ford"></constructor-arg>
<constructor-arg value="ChangAn"></constructor-arg>
<constructor-arg value="200000" type="double"></constructor-arg>
</bean>
</property>
</bean>
<bean id="person2" class="com.yczlab.spring.beans.Person">
<constructor-arg value="Jerry"></constructor-arg>
<constructor-arg value="25"></constructor-arg>
<!-- <constructor-arg ref="car"></constructor-arg> -->
<!--测试null值，属性为引用数据类型时，可以为其赋值为null，意义不大，因为这类数据默认初始化值就是null-->
<!-- <constructor-arg><null/></constructor-arg> -->
<constructor-arg ref="car"></constructor-arg>
<!-- 为级联属性赋值。注意：属性（car）需要先初始化后才能为级联属性赋值，否则会有异常 -->
<property name="car.maxSpeed" value="250"></property>
</bean>
</beans>
