Spring系列：IOC依赖查找（根据名称查找）实例

目录

​​code​​

​​pom.xml ​​

​​效果​​

---

code

package com.test.pojo;

import lombok.Data;

@Data
public class User {
    private long id ;
    private String name ;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

content.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">

    <!--实时查找-->
    <bean id="user" class="com.test.pojo.User">
        <property name="id" value="1"/>
        <property name="name" value="张明"/>
    </bean>
    <!--延迟查找-->
    <bean id="objectFactory" class="org.springframework.beans.factory.config.ObjectFactoryCreatingFactoryBean" >
        <property name="targetBeanName" value="user" />
    </bean>
 </beans>

package com.test;

import com.test.pojo.User;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Demo02101 {
    public static void main(String[] args) {

        /**
         * 实时查找
         */
        BeanFactory beanFactory = new ClassPathXmlApplicationContext("classpath:/META-INF/content.xml") ;
        User user = (User) beanFactory.getBean("user");
        System.out.println("实时查找："+user.toString());

        /**
         *  延迟查找
         */
        ObjectFactory<User> objectFactory = (ObjectFactory<User>) beanFactory.getBean("objectFactory");
        user = objectFactory.getObject() ;
        System.out.println("延迟查找："+ user.toString());
    }
}

ObjectFactory 对象并不是直接返回了实际的 Bean，而是一个 Bean 的查找代理。

当得到 ObjectFactory 对象时，相当于 Bean 没有被创建，只有当 getObject() 方法时，才会触发 Bean 实例化等生命周期。 

pom.xml 

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <packaging>pom</packaging>
  <modules>
    <module>demo021</module>
  </modules>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.4.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>
  <groupId>com.example</groupId>
  <artifactId>demo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>demo</name>
  <description>Demo project for Spring Boot</description>

  <properties>
    <java.version>1.8</java.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-api</artifactId>
      <version>5.5.0</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <optional>true</optional>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>

  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>

  <repositories>
    <repository>
      <id>spring-milestones</id>
      <name>Spring Milestones</name>
      <url>https://repo.spring.io/milestone</url>
    </repository>
    <repository>
      <id>spring-snapshots</id>
      <name>Spring Snapshots</name>
      <url>https://repo.spring.io/snapshot</url>
      <snapshots>
        <enabled>true</enabled>
      </snapshots>
    </repository>
  </repositories>
  <pluginRepositories>
    <pluginRepository>
      <id>spring-milestones</id>
      <name>Spring Milestones</name>
      <url>https://repo.spring.io/milestone</url>
    </pluginRepository>
    <pluginRepository>
      <id>spring-snapshots</id>
      <name>Spring Snapshots</name>
      <url>https://repo.spring.io/snapshot</url>
      <snapshots>
        <enabled>true</enabled>
      </snapshots>
    </pluginRepository>
  </pluginRepositories>

</project>

效果

取消注解

package com.test.pojo;

import com.test.anonation.VIP;
import lombok.Data;

@Data
//@VIP
public class VIPUser  extends User {
    private int age ;

    @Override
    public String toString() {
        return "VIPUser{" +
                "age=" + age +
                "} " + super.toString();
    }
}