案例要求：创建一个 Studentservice 类，其中需要使用 studentDao 接口的保存方法，来存储一个Student 类的对象，StudentDao 接口有两个不同的实现类，通过 Spring 的方式，为 Student类创建对象并为属性赋值，并通过 Spring 的方式，创建 Studentservice 类的对象以及StudentDao 接口的一个实现类对象，通过依赖注入的方式模拟完成保存的操作。

1、配置依赖

在pom.xml中配置依赖

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>5.2.0.RELEASE</version>
</dependency>

2、创建applicationContext.xml文件，并且点击File->Project...->找到Spring,点击+，选中文件导入

<?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="student" class="cn.clz.pojo.Student">
        <property name="name" value="海绵宝宝"></property>
        <property name="age" value="18"></property>
    </bean>
    <bean id="studentDao1" class="cn.clz.dao.impl.StudentDaoImpl1"></bean>
    <bean id="studentDao2" class="cn.clz.dao.impl.StudentDaoImpl2"></bean>
    <bean id="studentService" class="cn.clz.service.StudentService">
        <property name="studentDao" ref="studentDao1"></property>
    </bean>
</beans>

3、创建实体类Student、接口StudentDao、接口实现类StudentDaoImpl1和实现类StudentDaoImpl2、类StudentService

Student.java

public class Student {
    private  String name;
    private  int age;

    public Student() {
    }

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    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;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

StudentDao.java

public interface StudentDao {
    void save();
}

StudentDaoImpl1.java

public class StudentDaoImpl1 implements StudentDao {
    public void save() {
        System.out.println("实现类1实现StudentDao的save方法...");
    }
}

StudentDaoImpl1.java

public class StudentDaoImpl2 implements StudentDao {
    public void save() {
        System.out.println("实现类2实现StudentDao的save方法...");
    }
}

StudentService.java

public class StudentService {
    private  StudentDao studentDao;

    public void save(){
        studentDao.save();
    }

    public StudentDao getStudentDao() {
        return studentDao;
    }

    public void setStudentDao(StudentDao studentDao) {
        this.studentDao = studentDao;
    }
    
}

4、编写测试TestStudent.java

public class TestStudent {
    public static void main(String[] args) {
        //加载spring容器
        ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");
        Student student = (Student) ctx.getBean("student");
        StudentService studentService = (StudentService) ctx.getBean("studentService");
        System.out.println(student);
        studentService.save();
    }
}

5、运行结果