springBoot 配置拦截器

springBoot 配置拦截器

如何配置拦截器
拦截器设置容易出现的问题
如何取消拦截操作
实例：登录验证

如何配置拦截器

step1: 自定义拦截器

/**
 * 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，返回true才行进行下一步
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return false;
    }

    /**
     * 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 {
    }

    /**
     * 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 {
    }
}

step2：配置拦截器

@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);
    }
}

拦截器设置容易出现的问题

静态资源被拦截

MyInterceptorConfig 继承 WebMvcConfigurationSupport类时，会导致resources/static下的静态资源也被拦截，如果我们不想静态资源被拦截，可以尝试以下两种方法。

/**
* 在MyInterceptorConfig中重写addResourceHandlers方法，重新指定静态资源
* 推荐在前后端分离时使用，后台不需要访问静态资源
*
* @param registry
*/
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
   registry.addResourceHandler("/**").addResourceLocations(
           "classpath:/static/");
   super.addResourceHandlers(registry);
}

/**
 * 将MyInterceptorConfig类由继承WebMvcConfigurationSupport改为实现WebMvcConfigurer
 * 推荐在非前后端分离时使用，后台需要访问静态资源
 *
 */
@Configuration
public class MyInterceptorConfig implements WebMvcConfigurer {

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

如何取消拦截操作

step1：自定义注解

/**
 * 自定义注解用来指定某个方法不用拦截
 */
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface UnInterception {
}

step2：修改拦截器MyInterceptor中的preHandle方法

/**
 * 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 {
    
    UnInterception unInterception = method.getAnnotation(UnInterception.class);
    if(null != unInterception) {
        logger.info("不需要拦截，可以执行");
        return true;
    }

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

step3：在不需要拦截的controller上加上UnInterception注解

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

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

实例：登录验证

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