Spring06_纯注解配置

Posted 2020-12-23 CodeAction的博客

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本教程源码请访问：tutorial_demo

之前我们学习了如何使用注解实现IOC和DI，接下来我们学习一下如何完全抛弃XML配置，完全使用注解配置。

在学习纯注解之前先看一个完全用XML配置的案例，就当一个回顾。

一、一个例子-使用XML配置bean

需求：设计一个Person对象，包含username、age、gender、birthday四个属性，并使用Spring创建Person对象，并注入属性。

1.1、创建项目

在Idea中新建Maven工程；
工程创建完成后添加相应的坐标。

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.codeaction</groupId>
    <artifactId>anno</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.6.RELEASE</version>
        </dependency>
</project>

1.2、创建Person类

package org.codeaction.bean;

import java.io.Serializable;
import java.time.LocalDateTime;

public class Person implements Serializable {
    private String username;
    private int age;
    private String gender;
    //注意birthday的类型，思考如何为其注入值
    private LocalDateTime birthday;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public LocalDateTime getBirthday() {
        return birthday;
    }

    public void setBirthday(LocalDateTime birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "Person{" +
                "username=‘" + username + ‘‘‘ +
                ", age=" + age +
                ", gender=‘" + gender + ‘‘‘ +
                ", birthday=" + birthday +
                ‘}‘;
    }
}

1.3、添加XML配置文件

XML文件在resource目录下。

<?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person -->
    <bean id="person" class="org.codeaction.bean.Person">
       <property name="username" value="Tom"></property>
       <property name="age" value="20"></property>
       <property name="gender" value="男"></property>
       <property name="birthday" ref="birthday"></property>
   </bean>
    <!-- 配置birthday -->
    <bean id="birthday" class="java.time.LocalDateTime" factory-method="of">
        <constructor-arg name="date" ref="date"/>
        <constructor-arg name="time"  ref="time"/>
    </bean>

    <bean id="date" class="java.time.LocalDate" factory-method="of">
        <constructor-arg name="year" value="2000"/>
        <constructor-arg name="month" value="OCTOBER"/>
        <constructor-arg name="dayOfMonth" value="15"/>
    </bean>

    <bean id="time" class="java.time.LocalTime" factory-method="of">
        <constructor-arg name="hour" value="10" />
        <constructor-arg name="minute" value="10" />
        <constructor-arg name="second" value="20" />
    </bean>
</beans>

这里配置birthday比肩复杂，需要引用其它配置。

1.4、添加测试类

package org.codeaction.test;

import org.codeaction.bean.Person;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

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

运行main方法，输出如下：

Person{username=‘Tom‘, age=20, gender=‘男‘, birthday=2000-10-15T10:10:20}

上面就是我们完全使用XML，配置了Person，并注入了属性。

二、又是这个例子-使用XML和注解配置

结合上一篇教程，我们可以对这给程序使用基于注解的配置改造。有些步骤和上面是完全一样的，下面只列出关键代码。

2.1、修改Person类

package org.codeaction.bean;

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

import java.io.Serializable;
import java.time.LocalDateTime;

@Component
public class Person implements Serializable {
    @Value("Bob")
    private String username;
    @Value("20")
    private int age;
    @Value("男")
    private String gender;
    @Autowired
    private LocalDateTime birthday;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public LocalDateTime getBirthday() {
        return birthday;
    }

    public void setBirthday(LocalDateTime birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "Person{" +
                "username=‘" + username + ‘‘‘ +
                ", age=" + age +
                ", gender=‘" + gender + ‘‘‘ +
                ", birthday=" + birthday +
                ‘}‘;
    }
}

2.2、修改XML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
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">
    <!-- 告知spring创建容器时要扫描的包 -->
    <context:component-scan base-package="org.codeaction"></context:component-scan>

    <!-- 配置birthday -->
    <bean id="birthday" class="java.time.LocalDateTime" factory-method="of">
        <constructor-arg name="date" ref="date"/>
        <constructor-arg name="time"  ref="time"/>
    </bean>

    <bean id="date" class="java.time.LocalDate" factory-method="of">
        <constructor-arg name="year" value="2000"/>
        <constructor-arg name="month" value="OCTOBER"/>
        <constructor-arg name="dayOfMonth" value="15"/>
    </bean>

    <bean id="time" class="java.time.LocalTime" factory-method="of">
        <constructor-arg name="hour" value="10" />
        <constructor-arg name="minute" value="10" />
        <constructor-arg name="second" value="20" />
    </bean>
</beans>

由于类似于LocalDateTime这种类在JDK自带的包中，我们无法使用@Component注解让Spring容器去管理它的对象，以我们目前学习的知识，这里我们只能用XML去配置。

运行测试类中的main方法，控制台输出如下：

Person{username=‘Bob‘, age=20, gender=‘男‘, birthday=2000-10-15T10:10:20}

以上就是使用XML和注解进行配置，我们既然学习了注解，有没有什么办法能完全使用注解进行配置，抛弃XML？我们来看接下来的内容。

三、还是这个例子-完全使用注解配置

有些步骤和上面是完全一样的，下面只列出关键代码。Person类和2.1中完全相同。由于我们完全使用注解进行配置，我们删除beans.xml。

删除了beans.xml，就要有内容替代它，这里我们使用Java类（配置类）代替XML文件。

3.1、添加配置类

package org.codeaction.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

import java.time.LocalDateTime;
import java.time.Month;

@Configuration
@ComponentScan(basePackages = "org.codeaction.bean")
public class MainConfig {
    @Bean("birthday")
    public LocalDateTime dateTime() {
        return LocalDateTime.of(1980, Month.OCTOBER, 11, 12, 20, 15);
    }
}

@Configuration

作用：指定当前类是一个配置类。

注意：当配置类作为AnnotationConfigApplicationContext对象（3.2中会用到）创建的参数时，该注解可以不写。

@ComponentScan

作用：用于通过注解指定spring在创建容器时要扫描的包。这个注解等同于XML中的context:component-scan。

属性：value和basePackages的作用是一样的，都是用于指定创建容器时要扫描的包，用哪个都可以。

@Bean

作用：用于把当前方法的返回值作为bean对象存入Spring的IOC容器中。

属性：name，用于指定bean的id，当不写时，默认值是当前方法的名称。

注意：使用注解此配置方法时，如果方法有参数，Spring会去容器中查找有没有可用的bean对象。查找的方式和@Autowired注解的作用相同。

接下来我们看一下@Bean修饰的方法传参的情况，代码如下：

package org.codeaction.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Month;

@Configuration
@ComponentScan(basePackages = "org.codeaction.bean")
public class MainConfig {
    //方法有参数传入
    @Bean("birthday")
    public LocalDateTime dateTime(LocalDate date, LocalTime time) {
        //return LocalDateTime.of(1980, Month.OCTOBER, 11, 12, 20, 15);
        return LocalDateTime.of(date, time);
    }

    @Bean("date")
    public LocalDate date() {
        return LocalDate.of(1980, Month.OCTOBER, 11);
    }

    @Bean("time")
    public LocalTime time() {
        return LocalTime.of(12, 20, 15);
    }
}

通过上面的例子，我们可以看出@Bean修饰带参数的方法，Spring会去容器中查找有没有可用的bean对象。查找的方式和@Autowired注解的作用相同。

3.2、修改测试类

package org.codeaction.test;

import org.codeaction.bean.Person;
import org.codeaction.config.MainConfig;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyTest {
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(MainConfig.class);
        Person person = (Person) context.getBean("person");
        System.out.println(person);
    }
}

运行main方法，控制台输出如下：

Person{username=‘Bob‘, age=20, gender=‘男‘, birthday=1980-10-11T12:20:15}

以上完全使用注解配置的大部分内容都学完了，接下来我们结合案例来看一些其他常用的内容。

3.3、导入其他配置类

在3.1中，我们将所有的配置都写在了一个配置类中，如果有很多不同种类的配置，都写在同一个配置类中，代码会很庞大，难以维护，我们可以对配置进行拆分，然后通过导入的方式将所有配置整合在一起。

3.3.1、用来配置birthday的配置类

package org.codeaction.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Month;

@Configuration
public class BirthdayConfig {
    //方法有参数传入
    @Bean("birthday")
    public LocalDateTime dateTime(LocalDate date, LocalTime time) {
        //return LocalDateTime.of(1980, Month.OCTOBER, 11, 12, 20, 15);
        return LocalDateTime.of(date, time);
    }

    @Bean("date")
    public LocalDate date() {
        return LocalDate.of(1980, Month.OCTOBER, 11);
    }

    @Bean("time")
    public LocalTime time() {
        return LocalTime.of(12, 20, 15);
    }
}

我们将配置birthday的内容提取了出来，新建了一个配置类。

3.3.2、主配置类

我自己起的名字，大家把它当成汇总所有配置类的配置类就可以了

package org.codeaction.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

@Configuration
@ComponentScan(basePackages = "org.codeaction.bean")
@Import(BirthdayConfig.class)
public class MainConfig {
    
}

@Import：

作用：用于导入其他的配置类。

属性：value，用于指定其他配置类的字节码。当我们使用Import的注解之后，有Import注解的类就父配置类，而导入的都是子配置类。

运行3.2中的main方法，控制台输出如下：

Person{username=‘Bob‘, age=20, gender=‘男‘, birthday=1980-10-11T12:20:15}

3.4、一个特别要注意的情况-@Qualifier的另一个用法

在之前的学习中，我们学习了@Qualifier注解，作用如下：

在自动按照类型注入（@Autowried）的基础之上，再按照bean的id注入；
给方法注入参数；
在给属性注入时，不能独立使用，必须和@Autowired一起使用（我们目前案例讲的就是这种情况），给方法注入参数时，可以独立使用。

在属性上的使用已经学过了，我们看一下@Qualifier在方法上的使用，在学习之前，我们修改一下3.3.1中的配置类，代码如下：

package org.codeaction.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Month;

@Configuration
public class BirthdayConfig {
    //方法有参数传入
    @Bean("birthday")
    public LocalDateTime dateTime(LocalDate date, LocalTime time) {
        //return LocalDateTime.of(1980, Month.OCTOBER, 11, 12, 20, 15);
        return LocalDateTime.of(date, time);
    }

    @Bean("date1")
    public LocalDate date1() {
        return LocalDate.of(1980, Month.OCTOBER, 11);
    }

    @Bean("date2")
    public LocalDate date2() {
        return LocalDate.of(1980, Month.OCTOBER, 11);
    }
    @Bean("time1")
    public LocalTime time1() {
        return LocalTime.of(12, 20, 15);
    }

    @Bean("time2")
    public LocalTime time2() {
        return LocalTime.of(12, 20, 15);
    }
}

我们配置了两个LocalDate和两个LocalTime，运行测试类的main方法，报错，原因是因为Spring容器中有多个相同类型的bean对象，@Bean修饰的方法，无法通过自动注入的方式注入。控制台信息如下：

警告: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘person‘: Unsatisfied dependency expressed through field ‘birthday‘; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘birthday‘ defined in org.codeaction.config.BirthdayConfig: Unsatisfied dependency expressed through method ‘dateTime‘ parameter 0; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type ‘java.time.LocalDate‘ available: expected single matching bean but found 2: date1,date2
Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘person‘: Unsatisfied dependency expressed through field ‘birthday‘; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘birthday‘ defined in org.codeaction.config.BirthdayConfig: Unsatisfied dependency expressed through method ‘dateTime‘ parameter 0; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type ‘java.time.LocalDate‘ available: expected single matching bean but found 2: date1,date2
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:643)
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:130)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1422)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:594)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:895)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550)
	at org.springframework.context.annotation.AnnotationConfigApplicationContext.<init>(AnnotationConfigApplicationContext.java:89)
	at org.codeaction.test.MyTest.main(MyTest.java:11)
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘birthday‘ defined in org.codeaction.config.BirthdayConfig: Unsatisfied dependency expressed through method ‘dateTime‘ parameter 0; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type ‘java.time.LocalDate‘ available: expected single matching bean but found 2: date1,date2
	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:798)
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:539)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
	at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1306)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1226)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640)
	... 14 more
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type ‘java.time.LocalDate‘ available: expected single matching bean but found 2: date1,date2
	at org.springframework.beans.factory.config.DependencyDescriptor.resolveNotUnique(DependencyDescriptor.java:220)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1284)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1226)
	at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:885)
	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:789)
	... 27 more

使用@Qualifier修改如下：

package org.codeaction.config;

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

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Month;

@Configuration
public class BirthdayConfig {
    //方法有参数传入
    @Bean("birthday")
    public LocalDateTime dateTime(@Qualifier("date1") LocalDate date, @Qualifier("time1") LocalTime time) {
        //return LocalDateTime.of(1980, Month.OCTOBER, 11, 12, 20, 15);
        return LocalDateTime.of(date, time);
    }

    @Bean("date1")
    public LocalDate date1() {
        return LocalDate.of(1980, Month.OCTOBER, 11);
    }

    @Bean("date2")
    public LocalDate date2() {
        return LocalDate.of(1980, Month.OCTOBER, 11);
    }
    @Bean("time1")
    public LocalTime time1() {
        return LocalTime.of(12, 20, 15);
    }

    @Bean("time2")
    public LocalTime time2() {
        return LocalTime.of(12, 20, 15);
    }
}

这里我们在方法上使用@Qualifier，告诉Spring应该注入哪个bean的对象。

3.5、加载Properties文件中的配置

3.5.1、添加Properties配置文件

文件名：person.properties

位置：resource目录下

person.username=Tom
person.age=20
person.gender=男
person.year=2000
person.month=10
person.dayOfMonth=15
person.hour=10
person.minute=10
person.second=20

3.5.2、修改主配置类

package org.codeaction.config;

import org.springframework.context.annotation.*;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Month;

@Configuration
@ComponentScan(basePackages = "org.codeaction.bean")
@Import(BirthdayConfig.class)
@PropertySource("classpath:person.properties")
public class MainConfig {
//    //方法有参数传入
//    @Bean("birthday")
//    public LocalDateTime dateTime(LocalDate date, LocalTime time) {
//        //return LocalDateTime.of(1980, Month.OCTOBER, 11, 12, 20, 15);
//        return LocalDateTime.of(date, time);
//    }
//
//    @Bean("date")
//    public LocalDate date() {
//        return LocalDate.of(1980, Month.OCTOBER, 11);
//    }
//
//    @Bean("time")
//    public LocalTime time() {
//        return LocalTime.of(12, 20, 15);
//    }
}

@PropertySource

作用：用于加载.properties文件中的配置。

属性：value，用于指定properties文件位置。如果在类路径下，需要写上classpath:。

3.5.3、修改用来配置birthday的配置类加载配置

package org.codeaction.config;

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

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;

@Configuration
public class BirthdayConfig {
    @Value("${person.year}")
    private int year;
    @Value("${person.month}")
    private int month;
    @Value("${person.dayOfMonth}")
    private int dayOfMonth;
    @Value("${person.hour}")
    private int hour;
    @Value("${person.minute}")
    private int minute;
    @Value("${person.second}")
    private int second;

    //方法有参数传入
    @Bean("birthday")
    public LocalDateTime dateTime(LocalDate date, LocalTime time) {
        //return LocalDateTime.of(1980, Month.OCTOBER, 11, 12, 20, 15);
        return LocalDateTime.of(date, time);
    }

    @Bean("date")
    public LocalDate date() {
        return LocalDate.of(year, month, dayOfMonth);
    }

    @Bean("time")
    public LocalTime time() {
        return LocalTime.of(hour, minute, second);
    }
}

3.5.4、修改Person类加载配置

package org.codeaction.bean;

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

import java.io.Serializable;
import java.time.LocalDateTime;

@Component
public class Person implements Serializable {
    @Value("${person.username}")
    private String username;
    @Value("${person.age}")
    private int age;
    @Value("${person.gender}")
    private String gender;
    @Autowired
    private LocalDateTime birthday;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public LocalDateTime getBirthday() {
        return birthday;
    }

    public void setBirthday(LocalDateTime birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "Person{" +
                "username=‘" + username + ‘‘‘ +
                ", age=" + age +
                ", gender=‘" + gender + ‘‘‘ +
                ", birthday=" + birthday +
                ‘}‘;
    }
}

运行3.2中的main方法，控制台输出如下：

Person{username=‘Tom‘, age=20, gender=‘男‘, birthday=2000-10-15T10:10:20}

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