通过FactoryMethod创建对象示例

合集 - Spring5 源码(13)

1.1 FactoryBean接口的使用2024-03-052.4 Spring5 自定义标签案例2024-02-213.7 spring 识别自定义实现BeanFactoryPostProcessor 的接口2024-02-214.8 springboot源码解析(四)：监听器2024-03-055.11 replace-method标签使用2024-03-136.10 lookup-method标签使用2024-03-13

7.通过FactoryMethod创建对象示例2024-03-18

8.通过Supplier创建对象示例2024-04-149.InstantiationAwareBeanPostProcessor 接口实现2024-03-1810.对象Constructor构造函数和@PostConstruct&@PreDestroy解析详解2024-03-2211.自定义转换器Converter实现案例2024-03-2212.三级缓存解析过程2024-03-2513.JDK proxy 和cglib 源码解读2024-04-08

收起

factory-bean： 指定使用哪个工程实例，实例工厂，非静态方法创建bean
factory-method：指定使用哪个工厂实例的方法。静态工厂，静态方法创建bean
判断的依据是 创建bean的方法是否存在 static 修饰符。
具体code 如下：

package com.gientech.factoryMethod;

public class Person {

    private int id;
    private String name;
    private int age;
    private String gender;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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;
    }

    public String getGender() {
        return gender;
    }

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

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

创建静态方法

package com.gientech.factoryMethod;

public class PersonStaticFactory {

    public static Person getPerson(String name){
        Person person = new Person();
        person.setId(1);
        person.setName(name);
        return person;
    }
}

package com.gientech.factoryMethod;

public class PersonInstanceFactory {

    public Person getPerson(String name){
        Person person = new Person();
        person.setId(2);
        person.setName(name);
        return person;

    }
}

创建配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- factory-method : 静态工厂， 指定使用哪个工厂实例的方法 -->
    <bean id="person" class="com.gientech.factoryMethod.PersonStaticFactory" factory-method="getPerson">
        <constructor-arg value="zhangsan"></constructor-arg>
    </bean>

    <!-- factory-bean : 实例工厂，指定使用哪个工程实例， -->
    <bean id="personInstanceFactory" class="com.gientech.factoryMethod.PersonInstanceFactory"></bean>
    <bean id="person2" class="com.gientech.factoryMethod.Person" factory-bean="personInstanceFactory" factory-method="getPerson">
        <constructor-arg value="lisi"></constructor-arg>
    </bean>
</beans>

创建测试类

package com.gientech.factoryMethod;

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

public class FactoryMethodTest {
    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("factoryMethod.xml");
        Person person = ac.getBean("person", Person.class);
        System.out.println(person);
        Person person2 = ac.getBean("person2", Person.class);
        System.out.println(person2);
    }
}

运行结果如下：

factoryMethod 执行流程

nstantiateUsingFactoryMethod方法执行流程图如下：