畢設20200529 Spring Boot 1 Spring Boot 2設置默認首頁的正確姿勢（三種方法） - 如何訪問localhost:8080直接打開swagger-ui界面

※需要配置Swagger-ui，並使用Spring Boot 2的看官直接看方法2.2即可。

方法一：DefaultController實現

首先申明：這個方法適合自己項目裏面帶的index頁面使用，不適合swagger-ui.html使用（跳轉不過去，也顯示不了內容，親測）

@Controller
@RequestMapping("/")
public class DefaultController {
    @RequestMapping("/")
    public String index()  {
        return "forward:index.html";
    }
}

方法二：使用SpringDefaultView實現

2.1 Spring老版本中的寫法

代碼如下：

@Configuration
public class DefaultView extends WebMvcConfigurerAdapter {

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("forward:swagger-ui.html");
        registry.setOrder(Ordered.HIGHEST_PRECEDENCE);
        super.addViewControllers(registry);
    }
}

2.2 Spring5中的正確姿勢

我們可以看到繼承的WebMvcConfigurerAdapter已經過時(或不推薦使用)，用@Deprecated標註了

查看它的源碼發現：

/**
 * An implementation of {@link WebMvcConfigurer} with empty methods allowing
 * subclasses to override only the methods they're interested in.
 *
 * @author Rossen Stoyanchev
 * @since 3.1
 * @deprecated as of 5.0 {@link WebMvcConfigurer} has default methods (made
 * possible by a Java 8 baseline) and can be implemented directly without the
 * need for this adapter
 */
@Deprecated
public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {

翻譯：在Spring5.0 中WebMvcConfigurer有默認的方法（Java8使之成爲可能），可以直接被implements而不需要用這個類了。

代碼如下：

@Configuration
public class DefaultView implements WebMvcConfigurer {

    /**
     * Configure simple automated controllers pre-configured with the response
     * status code and/or a view to render the response body. This is useful in
     * cases where there is no need for custom controller logic -- e.g. render a
     * home page, perform simple site URL redirects, return a 404 status with
     * HTML content, a 204 with no content, and more.
     */
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addRedirectViewController("/","swagger-ui.html");
        registry.setOrder(Ordered.HIGHEST_PRECEDENCE);
    }
}

方法三：Windows中配置監聽事件直接打開Swagger界面（親測僅適用於Windows）

代碼如下：

@Configuration
public class XxxApplication {

    @EventListener({ApplicationReadyEvent.class})
    public void ready() {
        System.out.println("Application is almost started ... opening the browser");
        //Homepage URL link here
        String url = "http://localhost:"+ port + File.separator +"swagger-ui.html";
        Runtime runtime = Runtime.getRuntime();
        try {
            runtime.exec("rundll32 url.dll,FileProtocolHandler " + url);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

其中port最好在application.properties裏面配置。