Spring手動獲取bean的四種方式

更新時間：2024年01月07日 08:51:09 作者：hvige

本文主要介紹了Spring手動獲取bean的四種方式，包括BeanFactoryPostProcessor接口，ApplicationContextAware接口，注解 @PostConstruct 初始化時獲取，啟動類ApplicationContext獲取這四種方法，感興趣的可以了解一下

一、實現(xiàn)BeanFactoryPostProcessor接口

@Component
public class SpringUtil implements BeanFactoryPostProcessor {

    private static ConfigurableListableBeanFactory beanFactory;

    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
    }

    /**
     * 通過name獲取 Bean對象
     * @param name
     * @return Object 一個以所給名字注冊的bean實例
     */
    public static  <T> T getBean(String name) {
        return (T) beanFactory.getBean(name);
    }

    /**
     * 通過class獲取Bean對象
     * @param clazz
     * @param <T>
     * @return
     */
    public static <T> T getBean(Class<T> clazz){
        return beanFactory.getBean(clazz);
    }

    /**
     * 如果BeanFactory包含一個與所給名稱匹配的bean對象，則返回true
     * @param name
     * @return
     */
    public static boolean containsBean(String name){
        return beanFactory.containsBean(name);
    }

    /**
     * 判斷bean對象是一個singleton還是一個prototype
     * @param name
     * @return
     * @throws NoSuchBeanDefinitionException
     */
    public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException{
        return beanFactory.isSingleton(name);
    }

    /**
     * 通過 name獲取 bean 的類型
     * @param name
     * @return
     * @throws NoSuchBeanDefinitionException
     */
    public static Class<?> getType(String name) throws NoSuchBeanDefinitionException{
        return beanFactory.getType(name);
    }

    /**
     * 通過 name 獲取 bean定義的別名
     * @param name
     * @return
     */
    public static String[] getAliases(String name){
        return beanFactory.getAliases(name);
    }
}

二、實現(xiàn)ApplicationContextAware接口

@Component
public class BeanUtil implements ApplicationContextAware {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        BeanUtil.applicationContext = applicationContext;
    }
    /**
     * 獲取applicationContext
     *
     * @return
     */
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }
    /**
     * 通過name獲取 Bean對象
     *
     * @param name
     * @return
     */
    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    /**
     * 通過class獲取Bean對象
     * @param clazz
     * @param <T>
     * @return
     */
    public static <T> T getBean(Class<T> clazz) {
        return getApplicationContext().getBean(clazz);
    }

    /**
     * 通過name和Class返回指定的Bean對象
     *
     * @param name
     * @param clazz
     * @param <T>
     * @return
     */
    public static <T> T getBean(String name, Class<T> clazz) {
        return getApplicationContext().getBean(name, clazz);
    }

    /**
     * 獲取當前的環(huán)境配置
     * @return
     */
    public static String[] getActiveProfiles(){
        return getApplicationContext().getEnvironment().getActiveProfiles();
    }
}

三、注解 @PostConstruct 初始化時獲取

@Component
public class BeanStatic {

    @Autowired
    private TestService testService;

    @Autowired
    private static TestService staticTestService;

    /**
     * 用于在依賴關系注入完成之后需要執(zhí)行的方法上
     * 執(zhí)行任何初始化操作
     */
    @PostConstruct
    public void init() {
        // 初始化時把testService對象賦值給當前類定義的靜態(tài)變量
        staticTestService = testService;
    }

    // 在當前類調(diào)用業(yè)務接口
    public static String getTest() {
        return staticTestService.test();
    }
}

四、通過啟動類ApplicationContext獲取

@SpringBootApplication
public class WebApplication {

    public static ConfigurableApplicationContext applicationContext;

    public static void main(String[] args) {
        System.out.println("正在啟動。。。");
        applicationContext = SpringApplication.run(WebApplication.class, args);
        System.out.println("啟動成功");
    }
}
調(diào)用方式
@RestController
@RequestMapping("/bean")
@Api(tags = "手動獲取Bean對象測試")
public class BeanController {

    @GetMapping("test1")
    @ApiOperation("方式一")
    @ApiOperationSupport(order = 1)
    public IResult test1()
    {
        TestService testService = SpringUtil.getBean(TestService.class);
        String result = testService.test();
        return IResult.success(result);
    }

    @GetMapping("test2")
    @ApiOperation("方式二")
    @ApiOperationSupport(order = 2)
    public IResult test2()
    {
        TestService testService = BeanUtil.getBean(TestService.class);
        String result = testService.test();
        return IResult.success(result);
    }

    @GetMapping("test3")
    @ApiOperation("方式三")
    @ApiOperationSupport(order = 3)
    public IResult test3()
    {
        String result = BeanStatic.getTest();
        return IResult.success(result);
    }

    @GetMapping("test4")
    @ApiOperation("方式四")
    @ApiOperationSupport(order = 4)
    public IResult test4()
    {
        TestService testService = WebApplication.applicationContext.getBean(TestService.class);
        String result = testService.test();
        return IResult.success(result);
    }
}

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