@Autowired 注解是通过 java config 进行 bean 的自动装配
    在使用 @Autowired 的时候，需要在xml配置文件中添加这段代码

    1. <!-- 该 BeanPostProcessor 将自动对标注@Autowired 的 Bean 进行注入 -->
    2. <bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />

    案例代码：
    Person.java

    1. package com.baklib.custom;
    3. public class Person {
    5.     private String name;
    6.     private int age;
    8.     public Person() {
    9.     }
    11.     public Person(String name, int age) {
    12.         this.name = name;
    13.         this.age = age;
    14.     }
    16.     public String getName() {
    17.         return name;
    18.     }
    20.     public void setName(String name) {
    21.         this.name = name;
    22.     }
    24.     public int getAge() {
    25.         return age;
    26.     }
    28.     public void setAge(int age) {
    29.         this.age = age;
    30.     }
    31. }

    Car.java

    1. package com.baklib.custom;
    4. public class Car {
    6.     private float price;
    7.     private String name;
    9.     public Car() {
    10.     }
    12.     public Car(float price, String name) {
    13.         this.price = price;
    14.         this.name = name;
    15.     }
    17.     public float getPrice() {
    18.         return price;
    19.     }
    21.     public void setPrice(float price) {
    22.         this.price = price;
    23.     }
    25.     public String getName() {
    26.         return name;
    27.     }
    29.     public void setName(String name) {
    30.         this.name = name;
    31.     }
    32. }

    Action.java

    1. package com.baklib.custom;
    3. import org.springframework.beans.factory.annotation.Autowired;
    5. public class Action {
    7.     // 成员变量的自动装配
    8.     @Autowired
    9.     private Person person;
    10.     @Autowired
    11.     private Car car;
    13.     public Action() {
    14.     }
    16.     // 构造方法的自动装配
    17.     @Autowired
    18.     public Action(Person person, Car car) {
    19.         this.person = person;
    20.         this.car = car;
    21.     }
    23.     public void buyCar() {
    24.         System.out.println(person.getName() + "今年" + person.getAge() + "岁，花了"
    25.                 + car.getPrice() + "元买了" + car.getName());
    26.     }
    28. }

    MainApp.java

    1. package com.baklib.custom;
    3. import org.springframework.context.ApplicationContext;
    4. import org.springframework.context.support.ClassPathXmlApplicationContext;
    6. public class MainApp {
    9.     public static void main(String[] args) {
    11.         ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
    12.         Action action = (Action) context.getBean("action");
    13.         action.buyCar();
    15.     }
    17. }

    配置文件 Beans.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.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    6.     <bean id="person" class="com.baklib.custom.Person" >
    7.         <property name="name" value="张三" />
    8.         <property name="age" value="24" />
    9.     </bean>
    11.     <bean id="car" class="com.baklib.custom.Car">
    12.         <property name="name" value="小轿车" />
    13.         <property name="price" value="100000.0" />
    14.     </bean>
    16.     <bean id="action" class="com.baklib.custom.Action" />
    18.     <!-- 该 BeanPostProcessor 将自动对标注@Autowired 的 Bean 进行注入 -->
    19.     <bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />
    21. </beans>

    编写完以上代码，就可以运行这个程序，运行结束后，可以在控制台看到下面的信息

    1. 张三今年24岁，花了100000.0元买了小轿车