<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.websystique.spring</groupId><artifactId>Spring4HelloWorldExample</artifactId><version>1.0.0</version><packaging>jar</packaging><name>Spring4HelloWorldExample</name><properties><springframework.version>4.0.6.RELEASE</springframework.version></properties><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-core</artifactId><version>${springframework.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>${springframework.version}</version></dependency></dependencies><build><pluginManagement><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.2</version><configuration><source>1.6</source><target>1.6</target></configuration></plugin></plugins></pluginManagement></build></project>

第2步:创建一个POJO类

Spring提倡弱耦合以及面向接口编程。创建一个 POJO接口以及实现。此POJO将作为spring的bean.

package com.websystique.spring.domain;public interface HelloWorld {void sayHello(String name);
}

package com.websystique.spring.domain;public class HelloWorldImpl implements HelloWorld{public void sayHello(String name) {System.out.println("Hello "+name);}}

第3步: 创建Spring配置类

Spring配置类包含你应用中需要的bean的定义。@Configuration注解在类上，将其作为spring配置类。

@Bean注解的方法，定义了被spring容器管理的bean.

<pre class="java" name="code">package com.websystique.spring.configuration;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Description;@Configuration
public class HelloWorldConfig {@Bean(name="helloWorldBean")@Description("This is a sample HelloWorld Bean")public HelloWorld helloWorld() {return new HelloWorldImpl();}}

@Description 是 Spring4中提供的新的注解，目的是为追踪而为bean提供的一个文本解释。

上面对应的xml配置方式helloworld-config.xml

<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-4.0.xsd"><bean id="helloWorldBean" class="com.websystique.spring.domain.HelloWorldImpl"></beans>

第4步: 创建带Main方法的Java应用

<pre class="java" name="code">package com.websystique.spring;import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.AbstractApplicationContext;import com.websystique.spring.configuration.HelloWorldConfig;
import com.websystique.spring.domain.HelloWorld;public class AppMain {public static void main(String args[]) {AbstractApplicationContext context = new AnnotationConfigApplicationContext(HelloWorldConfig.class);HelloWorld bean = (HelloWorld) context.getBean("helloWorldBean");bean.sayHello("Spring 4");context.close();}}

AnnotationConfigApplicationContext 根据带有@Configuration 注解的类类创建Spring Application Context （Spring应用上下文）。

通过getBean 方法来获取Spring应用上下文中的特定bean .然后执行其中的方法：

HelloWorld bean = (HelloWorld) context.getBean("helloWorldBean");
bean.sayHello("Spring 4");

运行之后将产生如下输出：

Hello Spring 4

上面的例子如果基于XML方式如下：

package com.websystique.spring;import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;import com.websystique.spring.domain.HelloWorld;public class AppMain {public static void main(String args[]) {AbstractApplicationContext context = new ClassPathXmlApplicationContext("helloworld-config.xml");HelloWorld bean = (HelloWorld) context.getBean("helloWorldBean");bean.sayHello("Spring 4");context.close();}}

helloworld-config.xml在上面第3步中提到过。应该放在/src/main/resources这个类路径下。

项目代码下载:http://websystique.com/?smd_process_download=1&download_id=778