springboot 請求攔截器---含后端解決前端跨域問題

攔截器參考: https://www.jianshu.com/p/e52444f0a121

跨域參考: https://www.cnblogs.com/yuansc/p/9076604.html

 

 

 

創建一個Config來注冊攔截器，代碼如下：

MyMvcConfig    -----這個意義是 讓配置的一些接口，不需要走攔截器的邏輯

package com.config;

import com.controle.lanjie.LoginHandlerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {

    //所有的WebMvcConfigurerAdapter組件都會一起起作用
    @Bean //將組件注冊在容器中
    public WebMvcConfigurer webMvcConfigurerAdapter(){
        return new WebMvcConfigurer(){

            //注冊攔截器
            @Override
            public void addInterceptors(InterceptorRegistry registry) {
                //靜態資源； *.css,*.js
                //SpringBoot已經做好了靜態資源映射
                registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**");
//                .excludePathPatterns("/index.html","/","/user/login","/static/**","/webjars/**");
                // /**  表示攔截所有路徑下的所有請求
//                registry.addInterceptor(new LoginHandlerInterceptor())
//                        .addPathPatterns("/person.html","/Person.html",
//                                "/questionnaire.html","/Questionnaire.html",
//                                "/result.html","/Result.html");
            }
        };
    }

}

 

 

創建一個攔截器

LoginHandlerInterceptor

package com.controle.lanjie;

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

@Component
public class LoginHandlerInterceptor implements HandlerInterceptor {

    //目標方法執行之前
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        //--------------------------------------------------------添加請求頭，允許跨域----方法一
        setHeader(name, value)：如果Header中沒有定義則添加，如果已定義則用新的value覆蓋原用value值。
        addHeader(name, value)：如果Header中沒有定義則添加，如果已定義則保持原有value不改變。
        response.setHeader("Access-Control-Allow-Origin","*");
        response.setHeader("Access-Control-Allow-Headers", "*");
        //Access-Control-Allow-Methods: 真實請求允許的方法
        //Access-Control-Allow-Headers: 服務器允許使用的字段
        //Access-Control-Allow-Credentials: 是否允許用戶發送、處理 cookie
        //Access-Control-Max-Age: 預檢請求的有效期，單位為秒。有效期內，不會重復發送預檢請求
        
        
        //獲取請求參數
        Object user5 = request.getQueryString();
        System.out.println(user5);
        //獲取請求頭參數
        Object user6 = request.getHeader("currentUser");
        System.out.println(user6);
        //獲取請求方式
        Object user7 = request.getMethod();
        System.out.println(user7);
        //獲取請求路徑
        Object user8 = request.getRequestURI();
        System.out.println(user8);
        //重定向訪問路徑
        response.sendRedirect("/bbb2");
//        添加請求頭
        response.addHeader("location","http://baidu.com");
//        if (user == null) {
//            //未登錄,返回登錄頁面
//            System.out.println("第一攔截了，請求前");
////            response.sendRedirect("/LoginError.html");
//            return false;
//        }else {
//            //放行
            return true;
//        }
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
        System.out.println("第二攔截了，請求中");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {
        System.out.println("第三攔截了，請求后");
    }
}

 

 

允許前端跨域方法二 ----添加全局配置類

package com.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebConfig implements WebMvcConfigurer {

    /**
     * 跨域支持
     * @param registry
     */
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOrigins("*")
                .allowCredentials(true)
                .allowedMethods("GET", "POST", "DELETE", "PUT")
                .allowedHeaders("*")
				.maxAge(3600 * 24);
    }
}

 

還可以通過添加 Filter 的方式，配置 CORS 規則，並手動指定對哪些接口有效。---這個我沒試過，上面2種親測ok

@Bean
public FilterRegistrationBean corsFilter() {
    UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
    CorsConfiguration config = new CorsConfiguration();
    config.setAllowCredentials(true);    config.addAllowedOrigin("http://localhost:9000");
    config.addAllowedOrigin("null");
    config.addAllowedHeader("*");
    config.addAllowedMethod("*");
    source.registerCorsConfiguration("/**", config); // CORS 配置對所有接口都有效
    FilterRegistrationBean bean = newFilterRegistrationBean(new CorsFilter(source));
    bean.setOrder(0);
    return bean;
}

 

 

三更草堂是向下面那樣寫的 親測成功

bilibili.com/video/BV1U44y1W77D

package com.qingge.springboot.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import org.springframework.web.filter.CorsFilter;

@Configuration
public class CorsConfig {

    // 當前跨域請求最大有效時長。這里默認1天
    private static final long MAX_AGE = 24 * 60 * 60;

    @Bean
    public CorsFilter corsFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        CorsConfiguration corsConfiguration = new CorsConfiguration();
        corsConfiguration.addAllowedOrigin("*"); // 1 設置訪問源地址
        corsConfiguration.addAllowedHeader("*"); // 2 設置訪問源請求頭
        corsConfiguration.addAllowedMethod("*"); // 3 設置訪問源請求方法
        corsConfiguration.setMaxAge(MAX_AGE);
        source.registerCorsConfiguration("/**", corsConfiguration); // 4 對接口配置跨域設置
        return new CorsFilter(source);
    }
}

增加跨域配置解決的方法見 https://www.cnblogs.com/kaibindirver/p/16189077.html