[Java知识库]springboot使用上下文ApplicationContext

一、spring上下文

1.1 什么是spring上下文

1.2 spring上下文的作用

二、如何使用spring上下文

有四种方式获得spring上下文

• 方式一：实现ApplicationContextAware接口
• 方式二：非static方法版
• 方式三：在springboot引导类中设置
• 方式四；直接注入ApplicationContext

2.1 实现ApplicationContextAware接口

提供static方法供调用者使用，不要求使用者受spring容器管理

package net.facelib.eam.plancenter.webController.service.impl;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

/**
 * @author lc
 * @version 1.0
 * @date 2022/7/26 9:28
 */
@Component
public class MyTestService implements ApplicationContextAware {

    public static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        MyTestService.applicationContext = applicationContext;
    }

    public static ApplicationContext getApplicationContext() {
        return MyTestService.applicationContext;
    }

    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    public static <T>T getBean(Class clazz) {
        return (T)getApplicationContext().getBean(clazz);
    }

    public static <T>T getBean(String name, Class clazz) {
        return (T)getApplicationContext().getBean(name,clazz);
    }
}

2.2 同方法一，但是是非static方法版

使用者也得是被spring管理的bean，注入使用

2.3 在springboot引导类（启动类）里设置,此时就不需要实现ApplicationContextAware接口

@SpringBootApplication
public class MainApplication{

	public static void main(String[] args) {
		ConfigutableApplicationContext context = SpringApplication.run(MainApplication.clss,args)
		MyTestService.setApplicationContext(context);
	}

}

package net.facelib.eam.plancenter.webController.service.impl;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

/**
 * @author lc
 * @version 1.0
 * @date 2022/7/26 9:28
 */
@Component
public class MyTestService{

    public static ApplicationContext applicationContext;

   public static void setApplicationContext(ApplicationContext applicationContext) {
       MyTestService.applicationContext = applicationContext;
   }

    public static ApplicationContext getApplicationContext() {
        return MyTestService.applicationContext;
    }

    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    public static <T>T getBean(Class clazz) {
        return (T)getApplicationContext().getBean(clazz);
    }

    public static <T>T getBean(String name, Class clazz) {
        return (T)getApplicationContext().getBean(name,clazz);
    }
}

2.4 直接注入ApplicationContext

@Component
public class ContextUser{

	// 在需要使用上下文的地方直接注入，前提，被spring管理
	@Autowired
	public ApplicationContext applicationContext;
}