新建了一个Spring工程，有2个类：HelloWorld、Car。在Main.java文件里获取类时，发现只能获取到HelloWorld类，不能获取到Car类。
HelloWorld.java:
1 package com.tt.spring.beans;
2
3 public class HelloWorld {
4
5 private String name;
6
7 public void setName(String name) {
8 System.out.println("hello: "+ name);
9 this.name = name;
10 }
11
12 public void hello(){
13 System.out.println("hello: " + name);
14 }
15
16 public HelloWorld() {
17 System.out.println("HelloWorld‘s Constructor");
18 }
19
20
21 }
Car.java:
1 package com.tt.spring.beans;
2
3 public class Car {
4
5 private String brand;
6 private String corp;
7 private int price;
8 private int maxSpeed;
9
10
11 public Car() {
12 System.out.println("Car‘s Constructor");
13 }
14
15 public Car(String brand, String corp, int price) {
16 super();
17 this.brand = brand;
18 this.corp = corp;
19 this.price = price;
20 }
21
22 @Override
23 public String toString() {
24 return "Car [brand=" + brand + ", corp=" + corp + ", price=" + price + ", maxSpeed=" + maxSpeed + "]";
25 }
26
27 }
ApplicationContext.xml
1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans xmlns="http://www.springframework.org/schema/beans" 3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 4 xmlns:context="http://www.springframework.org/schema/context" 5 xsi:schemaLocation="http://www.springframework.org/schema/beans 6 http://www.springframework.org/schema/beans/spring-beans.xsd 7 http://www.springframework.org/schema/context/spring-context.xsd 8 http://www.springframework.org/schema/context/spring-context-3.0.xsd"> 9 10 <context:component-scan base-package="com.tt.spring.beans"></context:component-scan> 11 <!-- 12 配置bean 13 class:bean的全类名，通过反射的方式在IOC容器中创建Bean实例，所以要求Bean中必须有无参的构造器 14 id:标识容器中的bean，id唯一 15 --> 16 <bean id="helloWorld" class="com.tt.spring.beans.HelloWorld"> 17 <property name="name" value="Spring"></property> 18 </bean> 19 20 <!-- 通过构造方法来配置bean的属性 --> 21 <bean id="car" class="com.tt.spring.beans.Car"> 22 <constructor-arg value="Audi"></constructor-arg> 23 <constructor-arg value="chengdu"></constructor-arg> 24 <constructor-arg value="30000"></constructor-arg> 25 </bean> 26 27 </beans>
Main.java:
1 package com.tt.spring.beans;
2
3 import org.springframework.context.ApplicationContext;
4 import org.springframework.context.support.ClassPathXmlApplicationContext;
5
6 public class Main {
7
8 public static void main(String[] args){
9 /*
10 //创建HelloWorld的一个对象
11 HelloWorld helloWorld = new HelloWorld();
12 //为name属性赋值
13 helloWorld.setName("tt");
14 */
15 //调用hello方法
16
17 //1.创建Spring 的 IOC 容器对象
18 //ApplicationContext代表 IOC 容器
19 //ClassPathXmlApplicationContext:是ApplicationContext 接口的实现类，该实现类从类路径下来加载配置文件。
20 ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
21
22 //2.从IOC容器中获取Bean实例
23 //利用id定位到IOC容器中的bean
24 HelloWorld helloWorld = (HelloWorld) ctx.getBean("helloWorld");
25
26 //利用类型返回 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
27 //HelloWorld helloWorld = ctx.getBean(HelloWorld.class);
28
29 System.out.println(helloWorld);
30
31 //3.调用Hello方法
32 //helloWorld.hello();
33
34 Car car = (Car) ctx.getBean("car");
35 //Car car = ctx.getBean(Car.class);
36 System.out.println(car);
37
38 }
39 }
运行Main.java代码，打印信息如下：
HelloWorld‘s Constructor
hello: Spring
Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named ‘car‘ is defined
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:638)
at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1159)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:282)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:973)
at com.tt.spring.beans.Main.main(Main.java:34)
（待解答）Spring报错：Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'car' is defined