在@EnableWebMvc注解并且继承WebMvcConfigurerAdapter类的配置中重写addViewControllers方法：

@EnableWebMvc
@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {

@Override
public void addViewControllers(ViewControllerRegistry registry) {
    //设置默认首页
    registry.addViewController("/").setViewName("index");
    registry.setOrder( Ordered.HIGHEST_PRECEDENCE );
    super.addViewControllers(registry);
}
}