java每日一记 —— 常见的Bean后置处理器

1.上代码

public class Dome04Application {
    public static void main(String[] args) {
        // 这是一个干净的容器
        GenericApplicationContext context = new GenericApplicationContext();
        // 添加3哥Bean
        context.registerBean("andyBean01", Bean1.class);
        context.registerBean("andyBean02", Bean2.class);
        context.registerBean("andyBean03", Bean3.class);

        context.getDefaultListableBeanFactory().setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());

        // 注入解析Autowired注解的Bean
        // 执行时机：依赖注入
        context.registerBean(AutowiredAnnotationBeanPostProcessor.class);

        // 解析@Resource @PostConstruct @PreDestroy注解的Bean
        // 执行时机：依赖注入解析@Resource,初始化前执行@PostConstruct,销毁时执行@PreDestroy
        context.registerBean(CommonAnnotationBeanPostProcessor.class);

        // 注册@ConfigurationProperties注解的Bean
        ConfigurationPropertiesBindingPostProcessor.register(context.getDefaultListableBeanFactory());

        // 初始化
        context.refresh();
        // 销毁
        context.close();

    }
}

2.创建Bean1


public class Bean1 {
    private static final Logger log = LoggerFactory.getLogger(Bean1.class);

    private Bean2 bean2;

    @Autowired
    public void setBean2(Bean2 bean2) {
        log.debug("@Autowired 生效: {}", bean2);
        this.bean2 = bean2;
    }

    @Autowired
    private Bean3 bean3;

    @Resource
    public void setBean3(Bean3 bean3) {
        log.debug("@Resource 生效: {}", bean3);
        this.bean3 = bean3;
    }

    private String home;

    @Autowired
    public void setHome(@Value("${JAVA_HOME}") String home) {
        log.debug("@Value 生效: {}", home);
        this.home = home;
    }

    @PostConstruct
    public void init() {
        log.debug("@PostConstruct 生效");
    }

    @PreDestroy
    public void destroy() {
        log.debug("@PreDestroy 生效");
    }

    @Override
    public String toString() {
        return "Bean1{" +
               "bean2=" + bean2 +
               ", bean3=" + bean3 +
               ", home='" + home + ''' +
               '}';
    }
}

3.创建Bean2

public class Bean2 {
}

4.创建Bean3

public class Bean3 {
}

5.创建Bean4

@ConfigurationProperties(prefix = "java")
public class Bean4 {

    private String home;

    private String version;

    public String getHome() {
        return home;
    }

    public void setHome(String home) {
        this.home = home;
    }

    public String getVersion() {
        return version;
    }

    public void setVersion(String version) {
        this.version = version;
    }

    @Override
    public String toString() {
        return "Bean4{" +
               "home='" + home + ''' +
               ", version='" + version + ''' +
               '}';
    }
}