ClassPathXmlApplicationContext

基于classpath下xml格式的配置文件来创建

<?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">

    <bean class="com.xkj.org.ApplicationContextA.Bean1" id="bean1"></bean>

    <bean class="com.xkj.org.ApplicationContextA.Bean2" id="bean2">
        <property name="bean1" ref="bean1"></property>
    </bean>
</beans>

package com.xkj.org;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class ApplicationContextA {

    public static void main(String[] args) {
        testClassPathXmlApplicationContext();
    }

    private static void testClassPathXmlApplicationContext() {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("bean1.xml");
        String[] beanDefinitionNames = context.getBeanDefinitionNames();
        for (String beanDefinitionName : beanDefinitionNames) {
            System.out.println(beanDefinitionName);
        }
        Bean2 bean2 = context.getBean(Bean2.class);
        System.out.println(bean2.getBean1());

    }


    static class Bean1 {

    }

    static class Bean2 {

        private Bean1 bean1;

        public Bean1 getBean1() {
            return bean1;
        }

        public void setBean1(Bean1 bean1) {
            this.bean1 = bean1;
        }
    }
}

FileSystemXmlApplicationContext

基于磁盘路径下xml格式的配置文件夹创建

private static void testFileSystemXmlApplicationContext() {
        FileSystemXmlApplicationContext context =
                new FileSystemXmlApplicationContext("D:\\projects\\reggie_take_out\\src\\main\\resources\\bean1.xml");
        String[] beanDefinitionNames = context.getBeanDefinitionNames();
        for (String beanDefinitionName: beanDefinitionNames) {
            System.out.println(beanDefinitionName);
        }
        Bean2 bean2 = context.getBean(Bean2.class);
        System.out.println(bean2.getBean1());


    }

基于相对路径也可以：

 FileSystemXmlApplicationContext context =
                new FileSystemXmlApplicationContext("src\\main\\resources\\bean1.xml");

 内部原理：

 DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
        System.out.println("读取之前...");
        String[] beanDefinitionNames = beanFactory.getBeanDefinitionNames();
        for (String beanDefinitionName : beanDefinitionNames) {
            System.out.println(beanDefinitionName);
        }
        System.out.println("读取之后...");
        XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(beanFactory);
        reader.loadBeanDefinitions(new ClassPathResource("bean1.xml"));
        for(String name: beanFactory.getBeanDefinitionNames()) {
            System.out.println(name);
        }

AnnotationConfigApplicationContext

基于java配置类来创建

private static void testAnnotationConfigApplicationContext() {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
        for (String s : context.getBeanDefinitionNames()) {
            System.out.println(s);
        }
        Bean2 bean2 = context.getBean(Bean2.class);
        System.out.println(bean2.getBean1());
    }

private static void testAnnotationConfigApplicationContext() {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
        for (String s : context.getBeanDefinitionNames()) {
            System.out.println(s);
        }
        Bean2 bean2 = context.getBean(Bean2.class);
        System.out.println(bean2.getBean1());
    }


    @Configuration
    static class Config {
        @Bean
        public Bean1 bean1() {
            return new Bean1();
        }
        @Bean
        public Bean2 bean2(Bean1 bean1) {
            Bean2 bean2 = new Bean2();
            bean2.setBean1(bean1);
            return bean2;
        }
    }



    static class Bean1 {

    }

    static class Bean2 {

        private Bean1 bean1;

        public Bean1 getBean1() {
            return bean1;
        }

        public void setBean1(Bean1 bean1) {
            this.bean1 = bean1;
        }
    }

AnnotationConfigServletWebServerApplicationContext

基于java配置类来创建，用于web环境。

 private static void testAnnotationConfigServletWebServerApplicationContext() {
        AnnotationConfigServletWebServerApplicationContext context =
                new AnnotationConfigServletWebServerApplicationContext(WebConfig.class);
        for (String s : context.getBeanDefinitionNames()) {
            System.out.println(s);
        }

    }

@Configuration
    static class WebConfig{
        //servlet服务器
        @Bean
        public ServletWebServerFactory servletWebServerFactory() {
            return new TomcatServletWebServerFactory();
        }

        @Bean
        public DispatcherServlet dispatcherServlet() {
            return new DispatcherServlet();
        }

        //将dispatcherServlet给一个路径注册到servlet服务器
        @Bean
        public DispatcherServletRegistrationBean registrationBean(DispatcherServlet dispatcherServlet) {
            return new DispatcherServletRegistrationBean(dispatcherServlet, "/");
        }

        //控制器
        @Bean("/hello")
        public Controller controller1() {
            return (request ,response) -> {
              response.getWriter().print("hello");
              return null;
            };
        }

    }