spring+maven---use beans instead of traditional methods

Compare with the previous one: https://blog.csdn.net/weixin_42556863/article/details/108952582 .

---

Preface

Used xml to build the project

---

Tip: The following is the content of this article, the following cases are for reference

1. What is xml? (All code writers don’t like to read the text description)

XML is a markup language used to mark electronic files to make them structured.

Second, use steps

Precondition

Need to create a class and an interface respectively:

//SomeService.java
public interface SomeService {
    
    
    void doSome();
}

//SomeServiceImpl.java
public class SomeServiceImpl implements SomeService {
    
    
    @Override
    public void doSome() {
    
    
        System.out.println("执行了SomeServiceImpl中的doSome方法");
    }
}

1. Create the beans.xml file in the resource (right-click resource–>New–>XML Configuration File -->Spring Config)

2. Write beans.xml

The role of beans.xml:
tell spring to create an object.
Declaring a bean is to tell spring the object
id of a certain class to be created : the custom name and unique value of the object. Spring finds the object
class by name : the fully qualified name of the class (it cannot be an interface, because spring is a reflection mechanism to create objects, you must use the class) spring is done SomeService service1=new SomeServiceImpl();
spring is to place the created object in the map , There is a map to store objects in spring.
springMap.put (value of id, object);
For example: springMap.put("someService",new SomeServiceImpl());
A bean declares an object.

  <bean id="someService" class="com.kekek.service.impl.SomeServiceImpl" />

3. Write test cases

String name: names is an enumeration of foreach,
in fact

    for (String name:names) {
    
    
            System.out.println("容器中定义的对象名称："+name);
        }

Equivalent to

 for (int i = 0; i < names.length ; i++) {
    
    
            System.out.println("容器中定义的对象名称："+names[i]);
        }

Complete code

    @Test
    public void test03(){
    
    
    	//编写xml的名称
        String config="beans.xml";
        ApplicationContext ac=new ClassPathXmlApplicationContext(config);
        //使用spring提供的方法，获取容器中定义的对象的数量
        int nums=ac.getBeanDefinitionCount();
        System.out.println("容器中定义的对象数量："+nums);
        //容器中每个定义的对象的名称
        String names [] = ac.getBeanDefinitionNames();
        for (String name:names) {
    
    
            System.out.println("容器中定义的对象名称："+name);
        }
    }

operation result

There is only one bean in beans.xml, and the name is someService

---

Summary (the picture is relatively simple and easy to understand)