前后端分离,后台java配置前端域名处理跨域问题

前后端分离的话，经常是前端代码部署的服务器和后台部署的服务器不一样，域名也不一样。这个时候就会有跨域问题。我们可以通过前端的处理方式jsonp（基于js的无视域名调用和callback回调封装），但是这里只说后台java 的处理方式

代码：

跨域问题是浏览器控制台虽然会抛异常，但是仍然会发起这个请求。

后台设置响应头Access-Control-Allow-Origin表示了指定允许其他域名访问 ，也就是告诉浏览器，这个域名来的请求是可以接受的

所以我们配置一个过滤器;

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;

/**
 * 解决跨域请求
 *
 * @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<>();
    //这里配置上前端的域名
    allowedOrigins.add("https://www.baidu.com");
    allowedOrigins.add("http://www.baidu.com");
  

    String originHeader = request.getHeader("Origin");
    //这里判断请求的来源是不是我们的前端域名
    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() {}
}

这样就可以了