Spring boot 配置自己的拦截器

框架使用的是spring boot 2.0

首先，自定义拦截器实现HandlerInterceptor接口，preHandler是在执行controller方法前执行的  此外还有两个方法，具体作用最后才说，先熟悉以下拦截器的使用流程。

@Component
public class PassportInterceptor implements HandlerInterceptor{
    
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        HttpSession session = request.getSession();
        User user  = (User)session.getAttribute("user");
        if(user == null) {
            response.sendRedirect("/login");
            return false;
        }
        return true;
    }
    
}

上面拦截器只是简单的通过session验证是否登录

定义了自己的拦截器后就要实现 WebMvcConfigurer接口 注：该接口好像是spring boot 2.0以后有的  之前不是这个接口 该接口提供了方法添加拦截器，加上@Component注解  让其能被ioc容器管理

@Component
public class LabWebConfiguration implements WebMvcConfigurer{
    
    @Autowired
    PassportInterceptor passportInterceptor;
    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        
        registry.addInterceptor(passportInterceptor)
            .addPathPatterns("/**")
            .excludePathPatterns("/stylesheets/**", "/javascripts/**","/fonts/**",
                    "/images/**", "/login/**", "/regist/**");
    }
    

}

registry有三个重要的方法，addInterceptors()方法将自定义的拦截器添加进去 addPathPatterns 方法的主要作用是添加拦截器要拦截的路径，excludePathPatterns的功能则是配置对某些路径放行。上面我针对自己的静态资源、还有登录注册页面放行

接下来做一个小小的测试  测试以下拦截器各个方法的执行顺序

@Controller
public class TestController {

    @RequestMapping("/test")
    @ResponseBody
    public String testInterceptor() {
        
        System.out.println("Controller方法执行");
        
        return "test";
    }
    
}

@Component
public class TestInterceptor implements HandlerInterceptor{
    
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {    
        System.out.println("preHandler执行了");    
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        System.out.println("postHandler执行了");    
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        // TODO Auto-generated method stub
        System.out.println("afterCompletion执行了");    
    }
    
}

@Component
public class LabWebConfiguration implements WebMvcConfigurer{
    @Autowired
    TestInterceptor testInterceptor;
    
    @Override
        public void addInterceptors(InterceptorRegistry registry) {
            registry.addInterceptor(testInterceptor)
                .addPathPatterns("/test");
        }
    

}

结果如下

可见preHander方法只在Controller执行前   return true则放行 

postHandler则是在 具体的Controller方法执行后执行

afterCompletion  看资料说是在页面渲染完成后执行   因此可以用来作为资源的清理工作