spring框架学习记录 3

最新推荐文章于 2025-04-17 11:52:29 发布

原创最新推荐文章于 2025-04-17 11:52:29 发布 · 108 阅读

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本文深入探讨了Spring框架中的组件扫描机制，通过示例解析了如何使用@Component注解进行类注册，并介绍了BeanFactory与FactoryBean的作用及其实现方式。

context的component-scan

component.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"
       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">
    <context:component-scan base-package="com.component.*"></context:component-scan>

</beans>

package com.component.entity;

import org.springframework.stereotype.Component;

@Component("entity")// 如果注解中没有值，getbean中name为类名首字母小写，有值name则为参数值
public class Login {
    String account;
    String password;
    public Login(){
        System.out.println("@Component...");
    }
    public Login(String account, String password){
        this.account=account;
        this.password=password;
        System.out.println("@Component param...");
    }


}

Test.java

package com.component;

import com.component.controller.LoginController;
import com.component.dao.LoginDAO;
import com.component.dao.LoginDAOImpl;
import com.component.entity.Login;
import com.component.service.LoginService;
import com.component.service.LoginServiceImpl;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("component.xml");
        Login login = applicationContext.getBean("entity", Login.class);
        LoginController loginController = applicationContext.getBean("controllerId", LoginController.class);
        LoginDAO loginDAO = applicationContext.getBean("repositoryId", LoginDAOImpl.class);
        LoginService loginService = applicationContext.getBean("serviceId", LoginServiceImpl.class);
        System.out.println(login);
        System.out.println(loginController);
        System.out.println(loginDAO);
        System.out.println(loginService);
    }
}

Q:spring中，factorybean与beanFactory的区别

BeanFactory文件

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package org.springframework.beans.factory;

import org.springframework.beans.BeansException;
import org.springframework.core.ResolvableType;

public interface BeanFactory {
    String FACTORY_BEAN_PREFIX = "&";

    Object getBean(String var1) throws BeansException;

    <T> T getBean(String var1, Class<T> var2) throws BeansException;

    <T> T getBean(Class<T> var1) throws BeansException;

    Object getBean(String var1, Object... var2) throws BeansException;

    <T> T getBean(Class<T> var1, Object... var2) throws BeansException;

    boolean containsBean(String var1);

    boolean isSingleton(String var1) throws NoSuchBeanDefinitionException;

    boolean isPrototype(String var1) throws NoSuchBeanDefinitionException;

    boolean isTypeMatch(String var1, ResolvableType var2) throws NoSuchBeanDefinitionException;

    boolean isTypeMatch(String var1, Class<?> var2) throws NoSuchBeanDefinitionException;

    Class<?> getType(String var1) throws NoSuchBeanDefinitionException;

    String[] getAliases(String var1);
}

是ApplicationContext和ClassPathXmlApplicationContext的父接口，有常用的getBean方法，

BeanFactory文件

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package org.springframework.beans.factory;

public interface FactoryBean<T> {
    T getObject() throws Exception;

    Class<?> getObjectType();

    boolean isSingleton();
}

通过自定义类实现BeanFactory接口，实现