基于classpath下的xml格式的配置文件来创建bean对象

• java代码

  • package com.example;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    import org.springframework.context.support.FileSystemXmlApplicationContext;
    
    public class TestApplicationContext {
        private static final Logger log = LoggerFactory.getLogger(TestApplicationContext.class);
    
        public static void main(String[] args) {
            testClassPathXmlApplicationContext();
    
        }
    
        // todo 较为经典的容器、基于classpath下的xml格式的配置文件来创建
        private static void testClassPathXmlApplicationContext() {
            ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("b01.xml");
            for (String name : context.getBeanDefinitionNames()) {
                System.out.println(name);
            }
            System.out.println(context.getBean(Bean2.class).getBean1());
        }
    
    
    
        static class Bean1 {
        }
    
        static class Bean2 {
            private Bean1 bean1;
    
            public void setBean1(Bean1 bean1) {
                this.bean1 = bean1;
            }
    
            public Bean1 getBean1() {
                return bean1;
            }
        }
    }
    

•  xml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">
        <bean id="bean1" class="com.example.TestApplicationContext.Bean1"></bean>
        <bean id="bean2" class="com.example.TestApplicationContext.Bean2">
            <property name="bean1" ref="bean1"/>
        </bean>
    </beans>

• 在前面也讲过，ApplicationContext接口的实现需要BeanFactory接口的支持，具体见文章：BeanFactory与ApplicationContext_熵240的博客-CSDN博客
  ​​​​

  • 具体如下关键实现代码如下

    •         // todo 先创建一个beanFactory对象
              DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
              // todo 设置将读取目标存在哪一个beanFactory中
              XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(beanFactory);
              // todo 设置读取目标
              reader.loadBeanDefinitions(new ClassPathResource("b01.xml"));
              for (String name : beanFactory.getBeanDefinitionNames()) {
                  System.out.println(name);
              }

• 运行结果为
  •  

基于磁盘路径下的xml格式的配置文件来创建bean对象

• java代码

  • package com.example;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.beans.factory.support.DefaultListableBeanFactory;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    import org.springframework.context.support.FileSystemXmlApplicationContext;
    
    public class TestApplicationContext {
        private static final Logger log = LoggerFactory.getLogger(TestApplicationContext.class);
    
        public static void main(String[] args) {
    //        testClassPathXmlApplicationContext();
            testFileSystemXmlApplication();
        }
        
    
        // todo 基于磁盘路径下的xml格式的配置文件来创建bean对象
        private static void testFileSystemXmlApplication() {
            FileSystemXmlApplicationContext context =
                    new FileSystemXmlApplicationContext("D:\\JavaProject\\Spring\\Spring\\src\\main\\resources\\b01.xml");
            for (String name : context.getBeanDefinitionNames()) {
                System.out.println(name);
            }
    
        }
    
        static class Bean1 {
        }
    
        static class Bean2 {
            private Bean1 bean1;
    
            public void setBean1(Bean1 bean1) {
                this.bean1 = bean1;
            }
    
            public Bean1 getBean1() {
                return bean1;
            }
        }
    }
    

• xml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">
        <bean id="bean1" class="com.example.TestApplicationContext.Bean1"></bean>
        <bean id="bean2" class="com.example.TestApplicationContext.Bean2">
            <property name="bean1" ref="bean1"/>
        </bean>
    </beans>

• 同样的这种方法也是通过Beanfactory接口来具体实现的

  • 具体关键代码如下

    •         DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
              XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(beanFactory);
              reader.loadBeanDefinitions(new PathResource("D:\\JavaProject\\Spring\\Spring\\src\\main\\resources\\b01.xml"));
              for (String name : beanFactory.getBeanDefinitionNames()) {
                  System.out.println(name);
              }

• 运行结果如下

  • 

基于java配置类来创建bean对象

• java代码（配置类代码也写在一起了，一般讲是创建一个配置类）

  • package com.example;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    public class TestApplicationContext {
        private static final Logger log = LoggerFactory.getLogger(TestApplicationContext.class);
    
        public static void main(String[] args) {
    //        testClassPathXmlApplicationContext();
    //        testFileSystemXmlApplication();
            testAnnotationConfigApplicationText();
    
        }
    
        // todo 基于java配置类来创建bean对象
        private static void testAnnotationConfigApplicationText() {
            AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
            for (String name : context.getBeanDefinitionNames()) {
                System.out.println(name);
            }
        }
    
        // todo 创建一个配置类
        @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 void setBean1(Bean1 bean1) {
                this.bean1 = bean1;
            }
    
            public Bean1 getBean1() {
                return bean1;
            }
        }
    }