java之spring注解开发

• Z时代
• 2024-01-10
• 分类：综合

1、xml形式

Person.java

package com.jackhu.bean;
public class Person {
    private String name;
    private int 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 "com.jackhu.bean.Person{" +
                "name="" + name + """ +
                ", age=" + age +
                "}";
    }
    public Person(String name, int age) {
        super();
        this.name = name;
        this.age = age;
    }
    public Person() {
    }
}

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 http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="person" class="com.jackhu.bean.Person">
        <property name="name" value="zh"/>
        <property name="age" value="18"/>
    </bean>
</beans>

MainTest.java

public class MainTest {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
        Person person = (Person) applicationContext.getBean("person");
        System.out.println(person);
    }
}

运行结果如下：

2、注解形式

/**
 * 配置类==配置文件
 *
 * @Configuration 告诉Spring这是一个配置类
 * @Bean 给容器中注册一个Bean，类型为返回值类型，id默认是方法名作为id
 */
@Configuration
public class MainConfig {
    @Bean("person")
    public Person person2() {
        return new Person("JACK", 18);
    }
}

public class MainTest {
    public static void main(String[] args) {
        // 1、xml形式
//        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
//        Person person = (Person) applicationContext.getBean("person");
//        System.out.println(person);
        // 2、注解形式
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
        Person person = applicationContext.getBean(Person.class);
        System.out.println(person);
        String[] namesForType = applicationContext.getBeanNamesForType(Person.class);
        for (String name : namesForType) {
            System.out.println(name);
        }
    }
}

3、包扫描@ComponentScan

@Configuration
@ComponentScan(value = "com.jackhu")
public class MainConfig {
    @Bean("person")
    public Person person2() {
        return new Person("JACK", 18);
    }
}

测试类

public class IOCTest {
    @Test
    public void main() {
        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfig.class);
        // 容器中所有bean名称
        String[] names = applicationContext.getBeanDefinitionNames();
        for (String name : names) {
            System.out.println(name);
        }
    }
}

增加组件标记

输出结果：

源码解析：

@Configuration
@ComponentScan(value = "com.jackhu", excludeFilters = {
        @ComponentScan.Filter(type = FilterType.ANNOTATION, classes = {Controller.class, Service.class}) // excludeFilters排除 Controller和Service注解不加进来
})
public class MainConfig {
    @Bean("person")
    public Person person2() {
        return new Person("JACK", 18);
    }
}

includeFilters同理

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