public class WebInitializer implements WebApplicationInitializer {

    @Override
    public void onStartup(ServletContext arg0) throws ServletException {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(MyMvcConfig.class);
        ctx.setServletContext(arg0);
        Dynamic servlet = arg0.addServlet("dispatcher", new DispatcherServlet(ctx));
        servlet.addMapping("/");
        servlet.setLoadOnStartup(1);
    }

}

@Configuration
@EnableWebMvc
@ComponentScan
public class MyMvcConfig extends WebMvcConfigurerAdapter {
    @Bean
    public InternalResourceViewResolver viewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setPrefix("/WEB-INF/classes/views/");
        viewResolver.setSuffix(".jsp");
        viewResolver.setViewClass(JstlView.class);
        return viewResolver;
    }
    
    @Bean
    public DemoInterceptor demoInterceptor() {
        return new DemoInterceptor();
    }
    
    @Bean
    public MultipartResolver multipartResolver() {
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
        multipartResolver.setMaxUploadSize(1000000);
        return multipartResolver;
    }
    
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/assets/**").addResourceLocations("classpath:/assets/");
    }
    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(demoInterceptor());
    }
    
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/index").setViewName("/index");
        registry.addViewController("/toUpload").setViewName("/upload");
    }
}

@ConfigurationProperties(prefix = "druid")
public class DruidProperties {

    private String url;

        ...  
}

@Configuration
@EnableConfigurationProperties(DruidProperties.class)
@ConditionalOnClass(DruidDataSource.class)
@ConditionalOnProperty(prefix = "druid", name = "url")
@AutoConfigureBefore(DataSourceAutoConfiguration.class)
public class JpaConfig {
    @Autowired
    private DruidProperties properties;

    @Bean
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setUrl(properties.getUrl());
        dataSource.setUsername(properties.getUsername());
        dataSource.setPassword(properties.getPassword());
        if (properties.getInitialSize() > 0) {
            dataSource.setInitialSize(properties.getInitialSize());
        }
        if (properties.getMinIdle() > 0) {
            dataSource.setMinIdle(properties.getMinIdle());
        }
        if (properties.getMaxActive() > 0) {
            dataSource.setMaxActive(properties.getMaxActive());
        }
        dataSource.setTestOnBorrow(properties.isTestOnBorrow());
        try {
            dataSource.init();
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return dataSource;
    }
    
    @Bean 
    PlatformTransactionManager transactionManager() {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setDataSource(dataSource());
        return transactionManager;
    }
}