崛起于Springboot2.X之开发拦截器(21)

序言：几乎所有项目都需要拦截器，所以小伙伴们必须要掌握这门技术哦，不然只会mybaits增删改查那是实习生干的活呀。

1、创建拦截器类，implements HandlerInterceptor

public class MyIncerteptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("进入拦截器");

        HttpSession session = request.getSession();
        Admin user = (Admin) request.getSession().getAttribute("ADMIN_ACCOUNT");
        if (user == null) {
            //用户为空，重新登录
            response.sendRedirect(request.getContextPath() + "/login.html");
            return false;
        }
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}

2、配置文件，注册拦截器 implements

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {

        String[] addPathPatterns ={
                "/dtb/**"
        };
        String[] excludePathPatterns ={
                "/test/**"
        };
        InterceptorRegistration interceptorRegistration = registry.addInterceptor(new MyIncerteptor());
        interceptorRegistration.addPathPatterns(addPathPatterns);
        interceptorRegistration.excludePathPatterns(excludePathPatterns);
    }
}

addPathPatterns是拦截的那些目录，excludePathPatterns不拦截的路径，上面我们可以换一种常用的写法，只不过上面看上去更明白，interceptorRegistration获取的注册对象添加拦截器，并设置拦截路径

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {

        String[] addPathPatterns ={
                "/dtb/**"
        };
        String[] excludePathPatterns ={
                "/test/**"
        };
       registry.addInterceptor(new MyIncerteptor()).addPathPatterns(addPathPatterns).excludePathPatterns(excludePathPatterns);
    }
}

在优化一下，可以写成：

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        
       registry.addInterceptor(new MyIncerteptor()).addPathPatterns("/dtb/**").excludePathPatterns("/test/**");
    }
}

成功！其实就两个类就可以了。

3、注意点：

springboot2.0以后：使用spring5，废弃了WebMvcConfigurerAdapter,解决方案 implements WebMvcConfigurer

springboot2.0之前，1.X版本，使用spring4，使用拦截器需要 extends WebMvcConfigurerAdapter