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react 跨域访问后台，默认是有跨域问题，并且火弧和谷歌浏览器，对跨域问题展示还不一样.

谷歌浏览器如下图：

此处状态是200，然而在Response却没有任何信息，如下图

 

然而火弧浏览器，对该问题的描述，就清淅得多，

火弧浏览器告诉我们，跨域了，关于react跨域的帖子，网上也有相关帖子，搜索到的方法，大约都是如下解决方式：

如果你是通过creat-react-app构建的项目，请在package.json文件中的根目录下，添加"proxy": "http://api.xxxx.com"，如果你的项目，需要调用多个不同ip的接口，请使用如下配置：

"proxy": {
        "/api/RoomApi": {
          "target": "http://open.douyucdn.cn",
          "changeOrigin":true
        },
        "/api/v1":{
          "target":"http://capi.douyucdn.cn",
          "changeOrigin":true
        }
      }

对于antd-pro的项目，需要在package.json的同等目录下添加.roadhogrc文件，具体代码如下:

    {
      "entry": "src/index.js",
      "extraBabelPlugins": [
        "transform-runtime",
        "transform-decorators-legacy",
        "transform-class-properties",
        ["import", { "libraryName": "antd", "libraryDirectory": "es", "style": true }]
      ],
      "env": {
        "development": {
          "extraBabelPlugins": [
            "dva-hmr"
          ]
        }
      },
      "externals": {
        "g2": "G2",
        "g-cloud": "Cloud",
        "g2-plugin-slider": "G2.Plugin.slider"
      },
      "ignoreMomentLocale": true,
      "theme": "./src/theme.js",
      "proxy": {
        "/api": {
          "target": "http://api.xxxx.com/",
          "changeOrigin": true
        }
      }
    }

配置完成后，再次访问接口，还是出现一样的跨域问题，既然recat的配置，未解决跨域问题，我就把思路转到spring，在spring去处理跨域，在后端程序添加一个拦截器,

package com.gg.interceptor;

import java.util.ArrayList;
import java.util.List;
import java.util.Vector;

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

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

public class ProcessInterceptor implements HandlerInterceptor{

    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object handler)
            throws Exception {
        // TODO Auto-generated method stub 
        // 指定白名单域名   http://localhost:8000,http://localhost:8000
        List<String> whileList  = new Vector<String>(); 
        whileList.add("http://127.0.0.1:8000");
        whileList.add("http://localhost:8000");
        String clientIp = httpServletRequest.getHeader("origin");
        boolean status = false;
        for(String ip : whileList) {
            if(clientIp!=null&&clientIp.equals(ip)) {
                status = true;
                break;
            }
        }
        /**
         * 网上解决方案是httpServletResponse.setHeader("Access-Control-Allow-Origin","*");设置后发现，还是不能处理跨域问题，需要指定某一个ip，如：http://127.0.0.1:8000  
         * */
        httpServletResponse.setHeader("Access-Control-Allow-Origin",status?clientIp:null);  
        //响应头设置  
        httpServletResponse.setHeader("Access-Control-Allow-Headers", "Content-Type,Content-Length, Authorization, Accept,X-Requested-With");  
        //响应类型
        httpServletResponse.setHeader("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");  
        httpServletResponse.setHeader("X-Powered-By","Jetty");  
        httpServletResponse.setHeader("Access-Control-Allow-Credentials","true");
        String method= httpServletRequest.getMethod();  
        if (method.equals("OPTIONS")){  
            httpServletResponse.setStatus(200);  
            return false;  
        }  
  
        System.out.println(method+",status:"+status+",clientIp:"+clientIp);  
  
        return true;  
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        // TODO Auto-generated method stub
        
    }

}

spring-servlet.xml配置如下：

<mvc:interceptors>  
       <bean class="com.gg.interceptor.ProcessInterceptor"></bean>  
   </mvc:interceptors>  

react客户端代码如下：

Model层js代码:
*login({ payload }, { call, put }){
      let formData = new FormData();
      formData.append("loginId",payload.loginId);//账号
      formData.append("passWord",payload.passWord);//密码
      const response = yield call(requestGuangGao, formData); 
      yield put({
        type: 'changeLoginStatus',
        payload: response,
      });
    },

api层js代码:
export async function requestGuangGao(formData){
  // let formData = new FormData();
  // formData.append("loginId",params.loginId);
  // formData.append("passWord",params.passWord);

  console.log("requestGua   >url  :" );
   return request('http://127.0.0.1:8080/guanggao/userController/login.do', {
    method: 'POST', 
    mode: 'cors', 
    body:formData,
  });   
}

通过以下设置，react跨域问题就处理好了。