SpringBoot之拦截器优雅注入请求根目录到request中

在上一章节中我们讲解了Spring Boot中拦截器的基本使用步骤

在编写网页时我们难免需要用到请求的项目跟目录如http://localhost:8080，如果你不想使用相对路径的情况下

本次我们就通过拦截器为所需要的请求默认带上该变量，

OK，直接上代码：

首先我们实现一个PathInterceptor 拦截器

  @Component
  public class PathInterceptor implements HandlerInterceptor {
     private void printMsg(String msg) {
        System.out.println("[PathInterceptor] " +msg);

     }
     @Override
     public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        printMsg("preHandle");
        request.setAttribute("host", Utils.getHostPath(request));
        return true;
     }
     @Override
     public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
        ModelAndView modelAndView) throws Exception {
        printMsg("postHandle");
     }

     @Override
     public void afterCompletion(HttpServletRequest request, HttpServletResponse response, 
        Object handler, Exception exception) throws Exception {
        printMsg("afterCompletion");

     }
  }

拦截器写好了，此时就是要将我们的拦截器与Spring关联上并告知 如何调用了

通过实现一个WebMvcConfigurer，然后通过addInterceptors方法参数中的注册器注册拦截器

     @Component
    public class ProductServiceInterceptorAppConfig implements WebMvcConfigurer {
       @Autowired
       PathInterceptor pathInterceptor;

       @Autowired
       AdminLoginInterceptor adminLoginInterceptor;

       @Override
       public void addInterceptors(InterceptorRegistry registry) {
          registry.addInterceptor(pathInterceptor).addPathPatterns("/**"); //拦截所有目录


       }
    }

工具类如下：

 public class Utils {

     public static String getHostPath(HttpServletRequest request) {
         String host = "";
         host = request.getScheme() +"://" + request.getServerName()
                 + ":" +request.getServerPort();
         System.out.println("Utils host:" +host);
         return host;
     }
 }

ok，就是这么简单