Ali: Young man, can you give me some general ways to initialize Spring beans

preface

Instantiated by constructors instantiated by static factories instantiated by instance factories instantiated by FactoryBeans

RumenzA entity class

package com.rumenz;
public class RumenzA {

    private String id;
    private String name;
    
    public static RumenzA createRumenzA(){
        RumenzA rumenzA=new RumenzA();
        rumenzA.setId("123");
        rumenzA.setName(The Gateway Station);
        return rumenzA;
    }
    
    public  RumenzA() {
        System.out.println("RumenzA parametric construction method");
    }
    public RumenzA(String id) {
        this.id = id;
        System.out.println("ID constructor"); } / /setGet to omit}Copy the code

A constructor

beans.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 https://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="rumenz" class="com.rumenz.RumenzA" />
<bean id="rumenz1" class="com.rumenz.RumenzA">
     <constructor-arg name="id" value="1"/>
</bean>
</beans>
Copy the code

DemoApplication.java

package com.rumenz;

import org.springframework.context.support.ClassPathXmlApplicationContext;
public class DemoApplication {
    public static  void main(String[] args) {
        ClassPathXmlApplicationContext  ca=new ClassPathXmlApplicationContext("beans.xml");
        RumenzA rumenzA=(RumenzA)ca.getBean("rumenz"); }}Copy the code

The output

xxx.DefaultListableBeanFactory - Creating shared instance of singleton bean 'rumenz'RumenzA a no-parameter constructor XXX. DefaultListableBeanFactory - Creating Shared instance of singleton beans'rumenz1'ID constructorCopy the code

Static factory

beans.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 https://www.springframework.org/schema/beans/spring-beans.xsd">

<bean id="rFactory" class="com.rumenz.RumenzFactory" factory-method="rumenzFactory"/>
<bean id="rFactory1" class="com.rumenz.RumenzFactory" factory-method="rumenzFactory">
    <constructor-arg name="id" value="111"/>
</bean>
</beans>
Copy the code

RumenzFactory factory class

package com.rumenz; Public class RumenzFactory {// static method public static RumenzArumenzFactory() {return new RumenzA();
    }
    public static RumenzA rumenzFactory(String id){
        returnnew RumenzA(id); }}Copy the code

DemoApplication.java

package com.rumenz;

import org.springframework.context.support.ClassPathXmlApplicationContext;
public class DemoApplication {
    public static  void main(String[] args) {
        ClassPathXmlApplicationContext  ca=new ClassPathXmlApplicationContext("beans.xml"); }}Copy the code

The output

xxx.DefaultListableBeanFactory - Creating shared instance of singleton bean 'rFactory'RumenzA a no-parameter constructor XXX. DefaultListableBeanFactory - Creating Shared instance of singleton beans'rFactory1'ID constructorCopy the code

Instance factory instantiation

<? 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">
    <bean  id="rFactory" class="com.rumenz.RumenzFactory" />
    <bean id="rumenz" factory-bean="rFactory" factory-method="rumenzFactory"></bean>
    <bean id="rumenz1" factory-bean="rFactory" factory-method="rumenzFactory">
        <constructor-arg name="id" value="666"></constructor-arg>
    </bean>
</beans>
Copy the code

RumenzFactory.java

package com.rumenz; Public class RumenzFactory {// Static method public RumenzA cannot be usedrumenzFactory() {return new RumenzA();
    }
    public  RumenzA rumenzFactory(String id){
        returnnew RumenzA(id); }}Copy the code

DemoApplication.java

package com.rumenz;

import org.springframework.context.support.ClassPathXmlApplicationContext;
public class DemoApplication {
    public static  void main(String[] args) {
        ClassPathXmlApplicationContext  ca=new ClassPathXmlApplicationContext("beans.xml");
        //RumenzA rumenzA=(RumenzA)ca.getBean("rFactory1"); }}Copy the code

The output

xxx.DefaultListableBeanFactory - Creating shared instance of singleton bean 'rumenz'RumenzA a no-parameter constructor XXX. DefaultListableBeanFactory - Creating Shared instance of singleton beans'rumenz1'ID constructorCopy the code

Instantiation via FactoryBean

beans.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 https://www.springframework.org/schema/beans/spring-beans.xsd">
    
    <bean id="rumenz-by-factoryBean"  class="com.rumenz.RumenzAFactoryBean"/>
</beans>
Copy the code

RumenzAFactoryBean.java

package com.rumenz;

import org.springframework.beans.factory.FactoryBean;

public class RumenzAFactoryBean implements FactoryBean {
    @Override
    public Object getObject() throws Exception {
        returnRumenzA.createRumenzA(); } @Override public Class<? >getObjectType() {
        returnRumenzA.class; }}Copy the code

DemoApplication.java

package com.rumenz;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class DemoApplication {
    public static  void main(String[] args) {
        ClassPathXmlApplicationContext  ca=new ClassPathXmlApplicationContext("beans.xml");
        RumenzA rumenzA=(RumenzA)ca.getBean("rumenz-by-factoryBean"); }}Copy the code

Output/asynchronously load beans

xxx.DefaultListableBeanFactory - Creating shared instance of singleton bean 'rumenz-by-factoryBean'RumenzA parametric construction methodCopy the code

The last

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