前後端分離,後臺java配置前端域名處理跨域問題

前後端分離的話，經常是前端代碼部署的服務器和後臺部署的服務器不一樣，域名也不一樣。這個時候就會有跨域問題。我們可以通過前端的處理方式jsonp（基於js的無視域名調用和callback回調封裝），但是這裏只說後臺java 的處理方式

代碼：

跨域問題是瀏覽器控制檯雖然會拋異常，但是仍然會發起這個請求。

後臺設置響應頭Access-Control-Allow-Origin表示了指定允許其他域名訪問 ，也就是告訴瀏覽器，這個域名來的請求是可以接受的

所以我們配置一個過濾器;

package com.yeahka.online.shop.filter;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

/**
 * 解決跨域請求
 *
 * @author victor
 */
@Component
@Order(Integer.MIN_VALUE)
@WebFilter(urlPatterns = {"/*"})
public class SessionFilter implements Filter {


  private static Logger log = LoggerFactory.getLogger(SessionFilter.class);

  @Override
  public void init(FilterConfig filterConfig) {}

  @Override
  public void doFilter(
      ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
      throws IOException, ServletException {
   

    HttpServletRequest request = (HttpServletRequest) servletRequest;
    HttpServletResponse response = (HttpServletResponse) servletResponse;

   
    Set<String> allowedOrigins = new HashSet<>();
    //這裏配置上前端的域名
    allowedOrigins.add("https://www.baidu.com");
    allowedOrigins.add("http://www.baidu.com");
  

    String originHeader = request.getHeader("Origin");
    //這裏判斷請求的來源是不是我們的前端域名
    if (allowedOrigins.contains(originHeader)) {
      
      response.setHeader("Access-Control-Allow-Origin", "*");
      response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS");
      response.setHeader("Access-Control-Max-Age", "3600");
      response.setHeader("Access-Control-Allow-Headers", "content-type, x-requested-with,agentId");
      response.setHeader("Access-Control-Allow-Credentials", "true");
    }

    String uri = request.getRequestURI();
    log.info("filter_url:{}", uri);
    filterChain.doFilter(request, response);
  }

  @Override
  public void destroy() {}
}

這樣就可以了