spring 中各个配置文件的说明

（1）pom.xml

　　pom.xml文件是在整个项目下面，该xml的主要作用是：导入框架的jar包及其所依赖的jar包，导入的jar包是写在<dependencies></dependencies>中

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

  <modelVersion>4.0.0</modelVersion>

  <groupId>oracle.MavenPro</groupId>

  <artifactId>MyFirstPro</artifactId>

  <version>0.0.1-SNAPSHOT</version>

  <dependencies>

  <!-- https://mvnrepository.com/artifact/org.springframework/spring-core -->

    <dependency>

        <groupId>org.springframework</groupId>

        <artifactId>spring-core</artifactId>

        <version>5.1.1.RELEASE</version>

    </dependency>

  <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->

    <dependency>

        <groupId>org.springframework</groupId>

        <artifactId>spring-context</artifactId>

        <version>5.1.1.RELEASE</version>

    </dependency>

  </dependencies>

</project>

（2）spring.xml

　　spring.xml是通过spring框架来创建对象，而不需要在类中创建对象。

下面通过一个简单的sayhello例子来说明：

定义一个接口   ISayHello

package com.service;

public interface ISayHello {

    public void sayHello();

}

定义    接口ISayHello 的实现类　　SayHelloImple

package com.service.imple;

import com.service.ISayHello;

public class SayHelloImple implements ISayHello{

    @Override

    public void sayHello() {

        System.out.println("hello!!!");

    }

}

通过spring.xml来实例化对象，其中class属性是实现类的全路径，id是实例化对象的别名（hello）。

<?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-3.0.xsd">

     <bean id="hello" class="com.service.imple.SayHelloImple"></bean>

</beans>

其中下面这段代码是告诉spring，通过什么编码来解析<bean>

新建一个test类

package com.service;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.service.imple.SayHelloImple;

public class Test {

    public static void main(String[] args) {

        ApplicationContext context =

                new ClassPathXmlApplicationContext("spring.xml");

        SayHelloImple sayhello =

             (SayHelloImple) context.getBean("hello");

        sayhello.sayHello();

    }

}

下面这段代码是加载　　spring.xml　　文件

ApplicationContext context =

                new ClassPathXmlApplicationContext("spring.xml");

下面代码是获取实例化的对象hello

SayHelloImple sayhello =

             (SayHelloImple) context.getBean("hello");

运行结果为：