IDEA下——Spring入门程序

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1. 创建一个Maven的项目，我的项目结构如下：
   
2. 在pom文件里写下需要导入的依赖：

	<?xml version="1.0" encoding="UTF-8"?>
	<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>com.abc</groupId>
       <artifactId>01-first(Spring)</artifactId>
       <version>1.0-SNAPSHOT</version>
       <build>
           <plugins>
               <plugin>
                   <groupId>org.apache.maven.plugins</groupId>
                   <artifactId>maven-compiler-plugin</artifactId>
                   <configuration>
                       <source>6</source>
                      <target>6</target>
                   </configuration>
               </plugin>
           </plugins>
       </build>
       <properties>
           <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
           <maven.compiler.source>10</maven.compiler.source>
           <maven.compiler.target>10</maven.compiler.target>
           <spring.version>5.1.0.RELEASE</spring.version>
       </properties>
       <dependencies>
           <dependency>
               <groupId>org.springframework</groupId>
               <artifactId>spring-beans</artifactId>
               <version>${spring.version}</version>
           </dependency>
           <dependency>
               <groupId>org.springframework</groupId>
               <artifactId>spring-core</artifactId>
               <version>${spring.version}</version>
           </dependency>
           <dependency>
               <groupId>org.springframework</groupId>
               <artifactId>spring-context</artifactId>
               <version>${spring.version}</version>
           </dependency>
           <dependency>
               <groupId>org.springframework</groupId>
               <artifactId>spring-expression</artifactId>
               <version>${spring.version}</version>
           </dependency>
           <dependency>
               <groupId>org.springframework</groupId>
               <artifactId>spring-jcl</artifactId>
               <version>${spring.version}</version>
           </dependency>
           <dependency>
               <groupId>junit</groupId>
               <artifactId>junit</artifactId>
               <version>4.12</version>
               <scope>test</scope>
           </dependency>
       </dependencies>
       <build>
           <plugins>
               <plugin>
                   <artifactId>maven-compiler-plugin</artifactId>
                   <configuration>
                       <source>1.10</source>
                       <target>1.10</target>
                   </configuration>
               </plugin>
           </plugins>
       </build>
     </project>

3. 在Java文件夹下新建package，在package包下新建接口及其实现类
   接口：

       public interface SomeService {
   	          void doSome();
        }
   

   实现类：

       public class SomeServiceImpl implements SomeService {
   	public SomeServiceImpl() {
       	System.out.println("创建SomeServiceImpl对象");
   	}
   	
   	@Override
   	public void doSome() {
       	System.out.println("执行SomeServiceImpl里的doSome()方法");
   	}
       }
   

4. 在resources目录下新建applicationContext.xml文件

• 我们需要在spring容器的配置文件中进行注册该Bean
• spring使用的配置文件为xml文件，当然需要引入约束文件，一般将spring的配置文件命名为applicationContext.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
             http://www.springframework.org/schema/beans/spring-beans.xsd">	
   	<!--注册Servcie其造价于如下代码：   SomeServiceImpl someService = new SomeServiceImpl();
                  其底层是通过反射机制创建的someService对象
          Object someService = Class.forName("com.abc.service.SomeServiceImpl").newInstance();-->
   	           <bean id="someService" class="com.abc.service.SomeServiceImpl"/>
   </beans>
  

* spring的根元素是benas显然是注册Bean，子标签是Bean
* 注册:`<bean id="someService" class="com.abc.service.SomeServiceImpl"/>`
* id属性为了唯一确定一个对象，class属性里边应写类全名
5. 注册完毕后我们要在测试类中获取spring容器,而获取Spring容器有两种方式。

package com.abc.service;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

public class SomeServiceImplTTest {
	 // spring容器获取的两种方式
	 @Test
	 public void test01(){
	     //在类路径下加载Spring配置文件
	     ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
	     //在当前目录的根下加载该配置文件,路径应为文件实际存放的目录
	        ApplicationContext ac2 = new FileSystemXmlApplicationContext
                   ("D:\\IDEA-workspace\\01-first(Spring)\\src\\main\\resources\\applicationContext.xml");
	        System.out.println(ac2);
	  }    
	@Test
	public void test02() {
	     // 加载Spring配置文件，创建Spring容器对象
	     ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
		 //调用spring容器的getBean方法获取carImpl，方法参数为bean的id
	     SomeService service = (SomeService) ac.getBean("SomeService");
	     service.doSome();
	    }
	}

Spring入门程序到此就结束了