三种定义bean的方式

  

• 方法一：基于XML的bean定义（需要提供setter方法）

1.首先编写student.java和teacher.java两个类

    Student.java:

public class Student {

private String name;

private Teacher teacher;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public Teacher getTeacher() {
return teacher;
}

public void setTeacher(Teacher teacher) {
this.teacher = teacher;
}
}

  Teacher.java

                       public class Teacher {

private String name;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

}

2.配置spring.xml基于XML的bean定义（需要提供setter方法）

<?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 />          //设置属性值
</bean>
</beans>

 

• 方法二：基于注解的bean定义（不需要提供setter方法）

   

  @Component("teacher")
  public class Teacher {
  
  @Value("李四")
  private String name;
  
  public String getName() {
  return name;
  }
  
  }
  @Component("student")
  public class Student {
  
  @Value("张三")
  private String name;
  
  @Resource
  private Teacher teacher;
  
  public String getName() {
  return name;
  }
  
  public Teacher getTeacher() {
  return teacher;
  }
  

  <?xml version="1.0" encoding="UTF-8"?>
  <beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:context="http://www.springframework.org/schema/context"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
  http://www.springframework.org/schema/beans/spring-beans.xsd
  http://www.springframework.org/schema/context
  http://www.springframework.org/schema/context/spring-context.xsd">
  
  <!--扫描组件的包目录-->
  <context:component-scan base-package="test"/>
  
  </beans>

• 方法三：基于Java类的bean定义（需要提供setter方法）

  @Configuration
  public class BeansConfiguration {
  
  @Bean
  public Student student(){
  Student student=new Student();
  student.setName("张三");
  student.setTeacher(teacher());
  return student;
  }
  
  @Bean
  public Teacher teacher(){
  Teacher teacher=new Teacher();
  teacher.setName("李四");
  return teacher;
  }
  
  }

   

 

入口函数为：

public class Main {

public static void main(String args[]){
AnnotationConfigApplicationContext context=new AnnotationConfigApplicationContext(BeansConfiguration.class);
Student student= (Student) context.getBean("student");
Teacher teacher= (Teacher) context.getBean("teacher");
System.out.println("学生的姓名："+student.getName()+"。老师是"+student.getTeacher().getName());
System.out.println("老师的姓名："+teacher.getName());
}

}