spring 引用Bean的属性值

Posted 2021-02-03 Prince_Chang

引用Bean的属性值

从Spring3.0开始，可以通过#{beanName.beanProp}的方式方便地引用另一个bean的属性值
1、不需要使用PropertyPlaceholderConfigurer。
2、这里是井号

demo

1、xml配置实现

package test;

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

public class User {
    private String name;
    @Value("#{initUser.age}")
    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;
    }
}

User.java

package test;

class InitUser {
    private int age;
    private String name;
    public void initAgeName() throws InterruptedException {
        Thread.sleep(9000);
        this.age = 47;
        this.name  = "zs";
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

InitUser.java

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:p="http://www.springframework.org/schema/p"
       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">
     <!--开启包扫描，因为User类使用到了@Value注解；包扫描不支持裸体类上的注解 -->
    <context:component-scan base-package="test"/>
    <!-- 使用外部属性文件值赋值 -->
    <bean id="user" class="test.User" p:name="#{initUser.name}"/>
    <!-- 实例化InitUser -->
    <bean id="initUser" class="test.InitUser" init-method="initAgeName"/>
</beans>

my.xml

package test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Driver {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("my.xml");
        User user = context.getBean("user", User.class);
        System.out.println(user.getName());
        System.out.println(user.getAge());
    }
}

Driver.java

 2、Java配置实现

package test;

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

public class User {
    @Value("#{initUser.name}")
    private String name;
    @Value("#{initUser.age}")
    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;
    }
}

User.java

package test;

class InitUser {
    private int age;
    private String name;
    public void initAgeName() throws InterruptedException {
        Thread.sleep(9000);
        this.age = 47;
        this.name  = "zs";
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

InitUser.java

package test;

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

@Configuration
@ComponentScan// 因为使用了@Value注解，所以要开启包扫描
public class MyConfig {
    @Bean
    public InitUser initUser() throws InterruptedException {
        InitUser initUser = new InitUser();
        initUser.initAgeName();
        return initUser;
    }
    @Bean
    public User user() {
        return new User();
    }
}

MyConfig

package test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Driver {
    public static void main(String[] args) {
        ApplicationContext context = new AnnotationConfigApplicationContext(MyConfig.class);
        User user = context.getBean("user", User.class);
        System.out.println(user.getName());
        System.out.println(user.getAge());
    }
}

Driver.java