IDEA下——Spring入門程式

1. 創建一個Maven的項目，我的項目結構如下：
   
2. 在pom文件里寫下需要導入的依賴：

    <?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>

1. 在Java文件夾下新建package，在package包下新建介面及其實現類
   介面：
   public interface SomeService { void doSome(); }
   實現類：

       public class SomeServiceImpl implements SomeService {
       public SomeServiceImpl() {
           System.out.println("創建SomeServiceImpl對象");
       }
   
       @Override
       public void doSome() {
           System.out.println("執行SomeServiceImpl里的doSome()方法");
       }
       }

2. 在resources目錄下新建applicationContext.xml文件

• 我們需要在spring容器的配置文件中進行註冊該Bean

• spring使用的配置文件為xml文件，當然需要引入約束文件，一般將spring的配置文件命名為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">    
       <!--註冊Servcie其造價於如下代碼：   SomeServiceImpl someService = new SomeServiceImpl();
                  其底層是通過反射機制創建的someService對象
          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顯然是註冊Bean，子標簽是Bean
• 註冊:<bean id="someService" class="com.abc.service.SomeServiceImpl"/>
• id屬性為了唯一確定一個對象，class屬性裡邊應寫類全名

1. 註冊完畢後我們要在測試類中獲取spring容器,而獲取Spring容器有兩種方式。

    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容器獲取的兩種方式
         @Test
         public void test01(){
             //在類路徑下載入Spring配置文件
             ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
             //在當前目錄的根下載入該配置文件,路徑應為文件實際存放的目錄
                ApplicationContext ac2 = new FileSystemXmlApplicationContext
                       ("D:\\IDEA-workspace\\01-first(Spring)\\src\\main\\resources\\applicationContext.xml");
                System.out.println(ac2);
          }    
        @Test
        public void test02() {
             // 載入Spring配置文件，創建Spring容器對象
             ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
             //調用spring容器的getBean方法獲取carImpl，方法參數為bean的id
             SomeService service = (SomeService) ac.getBean("SomeService");
             service.doSome();
            }
        }

Spring入門程式到此就結束了