Spring框架获取ApplicationContext的方式

一、获取ApplicationContext的方法

1.通过ClassPathXmlApplicationContext获取;

2.通过FileSystemXmlApplicationContext获取;

3.通过AnnotationConfigApplicationContext获取;

4.通过继承ApplicationContextAware获取;

二、代码示例

如下示例提供4种方式获取ApplicationContext,然后再通过上下文获取Bean对象。

App.java文件:

public class App {
    public static void main( String[] args )
    {
        //方式1:spring-config.xml文件必须在jar包resource目录下
        ApplicationContext context1 = new ClassPathXmlApplicationContext("spring-config.xml");
        Bean1 b1 = context1.getBean(Bean1.class);
        System.out.println(b1.hello("b1"));

        //方式2:spring-config.xml文件必须在程序运行当前目录下
        ApplicationContext context2 = new FileSystemXmlApplicationContext("spring-config.xml");
        Bean1 b2 = context2.getBean(Bean1.class);
        System.out.println(b2.hello("b2"));

        //方式3:MyConfig设置ComponentScan的路径,并且Bean1使用@Component注解
        ApplicationContext context3 = new AnnotationConfigApplicationContext(MyConfig.class);
        Bean1 b3 = context3.getBean(Bean1.class);
        System.out.println(b3.hello("b3"));

        //方式4:MyContext实现ApplicationContextAware接口
        ApplicationContext context4 = MyContext.getApplicationContext();
        Bean1 b4 = context4.getBean(Bean1.class);
        System.out.println(b4.hello("b4"));
    }
}

 Bean1.java文件:

@Component
public class Bean1 {
    Bean1(){
        System.out.println("=================Bean1构造");
    }

    public String hello(String name){
        return  "=================hello " + name;
    }
}

spring-config.xml配置文件:(方式1和方式2使用) 




    

MyConfig.java文件:(方式3使用)

@Configuration
@ComponentScan({"com.gk"})
public class MyConfig {
    MyConfig(){
        System.out.println("=================MyConfig构造");
    }
}

MyContext.java文件:(方式4使用)

@Component
public class MyContext implements ApplicationContextAware {
    private static ApplicationContext myApplicationContext;
    MyContext(){
        System.out.println("=================MyContext构造");
    }
    @Override
    public void setApplicationContext(ApplicationContext context){
        myApplicationContext = context;
    }
    public static ApplicationContext getApplicationContext(){
        return myApplicationContext;
    }
}

pom文件中增加如下依赖:


        
            org.springframework
            spring-context
            4.2.6.RELEASE
        
        
            org.springframework
            spring-beans
            4.2.6.RELEASE
        
    

执行结果:

Spring框架获取ApplicationContext的方式_第1张图片

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