导读

用拦截器实现一个登录验证功能

step1：自定义拦截器

import com.kimmel.course13.annotation.UnInterception;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;

/**
 * 自定义拦截器
 */
public class MyInterceptor implements HandlerInterceptor {

    private static final Logger logger = LoggerFactory.getLogger(MyInterceptor.class);

    /**
     * 在请求匹配controller之前执行
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        HandlerMethod handlerMethod = (HandlerMethod) handler;
        Method method = handlerMethod.getMethod();
        String methodName = method.getName();

        // 判断用户有没有登录，一般登录之后的用户都有一个对应的token
        UnInterception unInterception = method.getAnnotation(UnInterception.class);
        String token = request.getParameter("token");
        if (null == token || "".equals(token)) {
            logger.info("用户未登录，没有权限执行{}请登录", methodName);
            return false;
        }

        // 返回true才会执行方法，返回false不会执行
        return true;
    }

    /**
     * 已经执行完controller了，但是还没有进入视图渲染
     * @param request
     * @param response
     * @param handler
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerMethod handlerMethod = (HandlerMethod) handler;
        Method method = handlerMethod.getMethod();
        String methodName = method.getName();
        logger.info("已经执行完{}了，但是还没有进入视图渲染", methodName);
    }

    /**
     * 视图也渲染完了，此时我可以做一些清理工作了
     * @param request
     * @param response
     * @param handler
     * @param ex
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        logger.info("视图也渲染完了，此时我可以做一些清理工作了");
    }
}

step2：配置拦截器

import com.kimmel.course13.Interceptor.MyInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

@Configuration
public class MyInterceptorConfig extends WebMvcConfigurationSupport {

    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**"); // 拦截所有内容:/** 拦截部分内容:/admin/**
        super.addInterceptors(registry);
    }

    /**
     * 发现如果继承了WebMvcConfigurationSupport，则在yml中配置的相关内容会失效。 需要重新指定静态资源
     *
     * @param registry
     */
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/**").addResourceLocations(
                "classpath:/static/");
        registry.addResourceHandler("swagger-ui.html").addResourceLocations(
                "classpath:/META-INF/resources/");
        registry.addResourceHandler("/webjars/**").addResourceLocations(
                "classpath:/META-INF/resources/webjars/");
        super.addResourceHandlers(registry);
    }
}

step3：自定义测试controller

@Controller
@RequestMapping("/interceptor")
public class InterceptorController {

    @RequestMapping("/test")
    public String test() {
        return "hello";
    }
}

step4：测试

进入浏览器，输入http://localhost:8080/interceptor/test
结果：无法进入，日志：用户未登录，没有权限执行 test 请登录
进入浏览器，输入http://localhost:8080/interceptor/test?token=1
结果：成功进入hello.html