Web组件

拦截器

拦截器是SpringMVC中一种对象，能拦截器对Controller的请求。

拦截器框架中有系统的拦截器， 还可以自定义拦截器。 实现对请求预先处理。

实现自定义拦截器：

创建类实现SpringMVC框架的HandlerInterceptor

常用第一种：
public interface HandlerInterceptor {
 default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
     return true;
 }

 default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
 }

 default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
}
}

2.需在SpringMVC的配置文件中，声明拦截器

<mvc:interceptors>
	<mvc:interceptor>
    	<mvc:path="url" />
        <bean class="拦截器类全限定名称"/>
    </mvc:interceptor>
</mvc:interceptors>

SpringBoot中注册拦截器：

@Configuration
public class MyAppConfig implements WebMvcConfigurer {

    //添加拦截器对象， 注入到容器中
    @Override
    public void addInterceptors(InterceptorRegistry registry) {

        //创建拦截器对象
        HandlerInterceptor interceptor = new LoginInterceptor();

        //指定拦截的请求uri地址
        String path []= {"/user/**"};
        //指定不拦截的地址
        String excludePath  [] = {"/user/login"};
        registry.addInterceptor(interceptor)
                .addPathPatterns(path)
                .excludePathPatterns(excludePath);
    }
}

例子：

config包下的Myconfig类

package com.kuangziyao.config;

import com.kuangziyao.web.LoginInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;


@Configuration
public class MyAppConfig implements WebMvcConfigurer {

    /**
     * 添加拦截器对象，注入到容器中
     *
     * @param registry
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // 创建拦截器请求对象
        HandlerInterceptor interceptor = new LoginInterceptor();

        // 指定拦截的请求uri地址
        String[] path = {"/user/**"};

        // 指定不拦截的请求uri地址
        String[] excludePath = {"/user/login"};

        // 添加拦截器请求对象、                   添加拦截地址、           添加不拦截地址
        registry.addInterceptor(interceptor).addPathPatterns(path).excludePathPatterns(excludePath);

    }
}

Controller层

package com.kuangziyao.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class BootController {

    @RequestMapping("/user/account")
    @ResponseBody
    public String userAccount() {
        return "访问user/account地址";
    }

    @RequestMapping("/user/login")
    @ResponseBody
    public String userLogin() {
        return "访问user/login地址";
    }

}

Web层

package com.kuangziyao.web;

import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 自定义拦截器
 * @author Answers.Bard
 */
public class LoginInterceptor implements HandlerInterceptor {

    /**
     *
     * @param request
     * @param response
     * @param handler  被拦截器的控制器对象
     * @return boolean
     *   true: 请求能被Controller处理
     *   false: 请求被截断
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("执行了LoginInterceptor的preHandle");
        return true;
    }
}

坂井泉水普通

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