我們知道如果我們要在一個(gè)類使用spring提供的bean對(duì)象，我們需要把這個(gè)類注入到spring容器中，交給spring容器進(jìn)行管理，但是在實(shí)際當(dāng)中，我們往往會(huì)碰到在一個(gè)普通的Java類中，想直接使用spring提供的其他對(duì)象或者說(shuō)有一些不需要交給spring管理，但是需要用到spring里的一些對(duì)象。如果這是spring框架的獨(dú)立應(yīng)用程序，我們通過(guò)

ApplicationContextac=newFileSystemXmlApplicationContext('applicationContext.xml');ac.getBean('beanId');

這樣的方式就可以很輕易的獲取我們所需要的對(duì)象。

但是往往我們所做的都是WebApplication，這時(shí)我們啟動(dòng)spring容器是通過(guò)在web.xml文件中配置，這樣就不適合使用上面的方式在普通類去獲取對(duì)象了，因?yàn)檫@樣做就相當(dāng)于加載了兩次spring容器，而我們想是否可以通過(guò)在啟動(dòng)web服務(wù)器的時(shí)候，就把Application放在某一個(gè)類中，我們通過(guò)這個(gè)類在獲取，這樣就可以在普通類獲取springbean對(duì)象了，讓我們接著往下看

下面介紹在SpringBoot中是如何使用的

1.在Spring Boot可以掃描的包下

寫的工具類為SpringUtil，實(shí)現(xiàn)ApplicationContextAware接口，并加入Component注解，讓spring掃描到該bean

springutil:

package me.shijunjie.util;import org.springframework.beans.BeansException;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;import org.springframework.stereotype.Component;@Componentpublic class SpringUtil implements ApplicationContextAware { private static ApplicationContext applicationContext; @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { if(SpringUtil.applicationContext == null) { SpringUtil.applicationContext = applicationContext; } System.out.println('---------------------------------------------------------------------'); System.out.println('---------------------------------------------------------------------'); System.out.println('---------------me.shijunjie.util.SpringUtil------------------------------------------------------'); System.out.println('========ApplicationContext配置成功,在普通類可以通過(guò)調(diào)用SpringUtils.getAppContext()獲取applicationContext對(duì)象,applicationContext='+SpringUtil.applicationContext+'========'); System.out.println('---------------------------------------------------------------------'); } //獲取applicationContext public static ApplicationContext getApplicationContext() { return applicationContext; } //通過(guò)name獲取 Bean. public static Object getBean(String name){ return getApplicationContext().getBean(name); } //通過(guò)class獲取Bean. public static <T> T getBean(Class<T> clazz){ return getApplicationContext().getBean(clazz); } //通過(guò)name,以及Clazz返回指定的Bean public static <T> T getBean(String name,Class<T> clazz){ return getApplicationContext().getBean(name, clazz); }}

為了測(cè)試，我們?cè)賳?dòng)的時(shí)候先通過(guò)代碼方式給spring容器中注入一個(gè)bean，入下所示

package me.shijunjie.config;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import me.shijunjie.entity.Demo2;@Configurationpublic class BeanConfig { @Bean(name='testDemo') public Demo2 generateDemo() { Demo2 demo = new Demo2(); demo.setId(12345); demo.setName('test'); return demo; }}

然后我們編寫測(cè)試controller，并從剛才寫的springutil中獲取這個(gè)bean

package me.shijunjie.controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import me.shijunjie.util.SpringUtil;@RestController@RequestMapping('/application')public class TestApplicationController { @RequestMapping('/test1') public Object testSpringUtil1() { return SpringUtil.getBean('testDemo'); } }

測(cè)試

啟動(dòng)web應(yīng)用，打開瀏覽器輸入http://localhost:8080/application/test1，測(cè)試成功

2不在Spring Boot的掃描包下

這種情況處理起來(lái)也很簡(jiǎn)單，先編寫SpringUtil類，同樣需要實(shí)現(xiàn)接口：ApplicationContextAware，具體編碼如下：

package me.shijunjie.util;import org.springframework.beans.BeansException;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;public class SpringUtil2 implements ApplicationContextAware { private static ApplicationContext applicationContext; @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { if(SpringUtil2.applicationContext == null) { SpringUtil2.applicationContext = applicationContext; } System.out.println('---------------------------------------------------------------------'); System.out.println('---------------------------------------------------------------------'); System.out.println('---------------me.shijunjie.util.SpringUtil------------------------------------------------------'); System.out.println('========ApplicationContext配置成功,在普通類可以通過(guò)調(diào)用SpringUtils.getAppContext()獲取applicationContext對(duì)象,applicationContext='+SpringUtil2.applicationContext+'========'); System.out.println('---------------------------------------------------------------------'); } //獲取applicationContext public static ApplicationContext getApplicationContext() { return applicationContext; } //通過(guò)name獲取 Bean. public static Object getBean(String name){ return getApplicationContext().getBean(name); } //通過(guò)class獲取Bean. public static <T> T getBean(Class<T> clazz){ return getApplicationContext().getBean(clazz); } //通過(guò)name,以及Clazz返回指定的Bean public static <T> T getBean(String name,Class<T> clazz){ return getApplicationContext().getBean(name, clazz); }}

使用@Bean注解，在App.java類中將SpringUtil注解進(jìn)

package me.shijunjie.controller;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.context.web.SpringBootServletInitializer;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.scheduling.annotation.EnableScheduling;import me.shijunjie.util.SpringUtil2;@ComponentScan(basePackages={'me.shijunjie'}) // 掃描該包路徑下的所有spring組件/*@EnableJpaRepositories('me.shijunjie.dao') // JPA掃描該包路徑下的Repositorie*//*@EntityScan('me.shijunjie.entity') // 掃描實(shí)體類*/@SpringBootApplication@EnableSchedulingpublic class App extends SpringBootServletInitializer{ @Bean public SpringUtil2 getSpringUtil2() { return new SpringUtil2(); } public static void main(String[] args) { SpringApplication.run(App.class, args); }}

測(cè)試（使用熱部署的需要重啟服務(wù)器）

啟動(dòng)web應(yīng)用，打開瀏覽器輸入http://localhost:8080/application/test2，測(cè)試成功

除此以外，也可以在App.java中使用@Import進(jìn)行導(dǎo)入。

package me.shijunjie.controller;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.context.web.SpringBootServletInitializer;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Import;import org.springframework.scheduling.annotation.EnableScheduling;import me.shijunjie.util.SpringUtil2;@ComponentScan(basePackages={'me.shijunjie'}) // 掃描該包路徑下的所有spring組件/*@EnableJpaRepositories('me.shijunjie.dao') // JPA掃描該包路徑下的Repositorie*//*@EntityScan('me.shijunjie.entity') // 掃描實(shí)體類*/@SpringBootApplication@EnableScheduling@Import(SpringUtil2.class)public class App extends SpringBootServletInitializer{ /*@Bean public SpringUtil2 getSpringUtil2() { return new SpringUtil2(); }*/ public static void main(String[] args) { SpringApplication.run(App.class, args); }}

跑出結(jié)果和上面相同

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