第一个spring项目

1、maven依赖导入

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.3.22</version>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.11</version>
    <scope>test</scope>
</dependency>

2、编写代码

2.1、不使用IOC容器

2.1.1、创建Hello实体类

public class Hello {
    private String name;

    public String getName() {
        return name;
    }

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

    public void show() {
        System.out.println("name= " + name);
    }
}

2.2、创建beans.xml

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- 配置Hello实体类 -->
    <bean id="hello" class="Hello">
        <!-- collaborators and configuration for this bean go here -->
    </bean>

    <!-- more bean definitions go here -->

</beans>

2.3、测试

public class MyTest {
    @Test
    public void helloSpring() {
        //1. 解析beans.xml文件，生成对应的bean管理context
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        //2. 得到根据bean id对应的bean
        Hello hello = context.getBean("hello", Hello.class);
        hello.setName("tom");
        hello.show();

    }
}

注意：这里未使用IOC容器

2.2、使用IOC容器

2.2.1、创建PetDao

public interface PetDao {
    void say();
}

2.2.2、创建Cat实现类

public class Cat implements PetDao {
    @Override
    public void say() {
        System.out.println("小猫喵喵叫");
    }
}

2.2.3、创建CatService

public class PetService {
    private PetDao petDao;

    //IOC使用set方法依赖注入
    public void setPetDao(PetDao petDao) {
        this.petDao = petDao;
    }

    public void say() {
        petDao.say();
    }

}

2.2.4、创建xml文件

• 创建services.xml

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- services -->

    <bean id="petService" class="com.example.service.PetService">
        <property name="petDao" ref="petDao"/>
        <!-- additional collaborators and configuration for this bean go here -->
    </bean>

    <!-- more bean definitions for services go here -->

</beans>

• 创建daos.xml

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="petDao"
          class="com.example.dao.impl.Cat">
        <!-- additional collaborators and configuration for this bean go here -->
    </bean>

    <!-- more bean definitions for data access objects go here -->

</beans>

2.2.5、测试

public class MyTest {
    @Test
    public void helloSpring() {
        //1. 解析beans.xml文件，生成对应的bean管理context
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        //2. 得到根据bean id对应的bean
        Hello hello = context.getBean("hello", Hello.class);
        hello.setName("tom");
        hello.show();
    }

    @Test
    public void test() {
        //1. 解析xml文件，生成对应的context
        ApplicationContext context = new ClassPathXmlApplicationContext("services.xml", "daos.xml");
        //2. 得到对应的bean
        PetService petService = context.getBean("petService", PetService.class);
        petService.say();
    }
}

3、结尾

创建类图：

Spring官方文档：https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#beans-basics