@Configuration：表示當前類充當Spring容器，即所有的Bean將由這個類來創建

註意：

　　在舉例之前聲明幾個問題：

　　1、註解需要依賴spring-aop-4.3.9.RELEASE.jar包，所以需要導入依賴包。

　　2、使用註解方式註入，配置文件需要添加約束頭文件：

<?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"
 
>

　　也可以自己從Spring的說明文檔中找到此頭文件：

　　3、如果使用到了SpringJUnit4測試，則還需要導入spring-test-4.3.9.RELEASE.jar包

二、舉例

1、首先創建一個School類：

package com.ietree.spring.basic.annotation.demo1;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("mySchool")
public class School {

    @Value(value = "清華大學")
    private String name;

    public School() {
        super();
    }

    public School(String name) {
        super();
        this.name = name;
    }

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

    @Override
    public String toString() {
        return "School [name=" + name + "]";
    }

}

創建Student類：

package com.ietree.spring.basic.annotation.demo1;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

/**
 * 說明：
 * [email protected]，但意義不同的註解還有三個：
 * 1）@Repository:註解在Dao實現類上
 * 2）@Service:註解在Service實現類上
 * 3）@Controller:註解在SpringMVC的處理器上
 * 
 * Bean作用域：
 * @Scope("prototype"):用於指定對象創建模式，可以是單例模式或者原型模式，默認是singleton
 * 
 * 基本類型屬性註入：
 * @Value
 * 
 * @Autowired:byType方式的註解式註入，即根據類型註解
 * @Qualifier("mySchool"):byName方式的註解式註入，[email protected]@Autowired聯合使用
 * 
 * 域屬性註解：
 * @Resource:不加name屬性則為byType方式的註解式註入，但前提是註入的對象只能有一個
 * @Resource(name="mySchool"):byName方式的註解式註入
 * 
 * Bean的生命始末：
 * @PostConstruct：當前Bean初始化剛完畢
 * @PreDestroy：當前Bean即將被銷毀
 */
//@Scope("prototype")
@Component("myStudent")
public class Student {

    @Value(value = "小明")
    private String name;
    
    @Value(value = "25")
    private int age;
    
    //    @Autowired
    //    @Qualifier("mySchool")
    //    @Resource(name="mySchool")
    @Resource
    private School school;// 對象屬性，也叫做域屬性

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

    public void setName(String name) {
        System.out.println("執行setName()");
        this.name = name;
    }

    public void setAge(int age) {
        System.out.println("執行setAge()");
        this.age = age;
    }

    public void setSchool(School school) {
        this.school = school;
    }

    @Override
    public String toString() {
        return "Student [name=" + name + ", age=" + age + ", school=" + school + "]";
    }
    
    @PostConstruct
    public void initAfter(){
        System.out.println("當前Bean初始化剛完畢");
    }
    
    @PreDestroy
    public void preDestroy(){
        System.out.println("當前Bean即將被銷毀");
    }
}

創建MyJavaConfig類：

package com.ietree.spring.basic.annotation.demo1;

import org.springframework.beans.factory.annotation.Autowire;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @Configuration：表示當前類充當Spring容器，即所有的Bean將由這個類來創建
 */
@Configuration
public class MyJavaConfig {
    
    @Bean(name="mySchool")
    public School mySchoolCreator(){
        return new School("清華大學");
    }
    
    // autowire=Autowire.BY_TYPE：指從當前類這個容器中查找與域屬性的類型具有is-a關系的Bean
    // autowire=Autowire.BY_NAME：指從當前類這個容器中查找與域屬性同名的Bean
    @Bean(name="myStudent", autowire=Autowire.BY_TYPE)
    public Student myStudentCreator(){
        return new Student("小明", 25);
    }
}

創建配置文件：

<?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">
    
    <!-- 掃描 com.ietree.spring.basic.annotation.demo1這個包及其子包 -->
    <context:component-scan base-package="com.ietree.spring.basic.annotation.demo1"/>
    
    <!-- 掃描 com.ietree.spring.basic這個包的子包 -->
    <context:component-scan base-package="com.ietree.spring.basic.*"/>
    
</beans>

創建測試類：

package com.ietree.spring.basic.annotation.demo1;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations="classpath:com/ietree/spring/basic/annotation/demo1/applicationContext.xml")
public class MyTest {
    
    @Autowired
    private Student student;
    
    @Test
    public void test01() {

        String resource = "com/ietree/spring/basic/annotation/demo1/applicationContext.xml";
        ApplicationContext ctx = new ClassPathXmlApplicationContext(resource);

        School school = (School) ctx.getBean("mySchool");
        System.out.println(school);

        Student student = (Student) ctx.getBean("myStudent");
        System.out.println(student);
        
        ((ClassPathXmlApplicationContext)ctx).close();
    }
    
    public void test02(){
        System.out.println(student);
    }
    
}

Spring框架第四篇之基於註解的DI註入