CORS解决跨域问题的几种方法

一 后端服务器使用过滤器

新建过滤器:

/**
 * 解决跨域
 */
public class AccessControlAllowOriginFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException { }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("解决跨域请求");
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        response.setHeader("Access-Control-Allow-Origin", "*");//允许所有网站跨域访问
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Allow-Credentials", "true");
        //这里如果前端请求header首字母是小写也是不行得,所以大小写都写上就没问题了
        response.setHeader("Access-Control-Allow-Headers", "access-control-allow-origin,content-type,x-requested-with,Content-Type,Access-Control-Allow-Headers,Content-Length,Accept,Authorization,X-Requested-With");
        filterChain.doFilter(servletRequest, response);
    }

    @Override
    public void destroy() {}
}

前端header需要添加:

$.ajax( {
            url : 'http://c2.zhuzher.com/pdm/know/active?hotelid=808047&sdate=2019-11-09&edate=2019-11-11',
            beforeSend: function (xhr) {
                    xhr.setRequestHeader("Access-Control-Allow-Origin", "*"); //设置跨域访问信息
                    xhr.setRequestHeader("Content-Type", "application/json;charset=utf-8");
            },
            type : 'get',
            dataType : 'json',
            data:{},
            success : function(data) {
                alert(1111);
            }
        });

二 后端接口springboot/springmvc使用注解

springMVC的版本要在4.2或以上版本才支持@CrossOrigin ;

方法需要指明Get或者POST才行:

三 本地nginx反向代理(推荐)

本地下载解压nginx,添加一个server配置文件:

注意,如果是放在nginx的html目录下一般是不需要加跨域配置的,否则会报配置多余错误

每次可先直接使用试试,不行再加下面add_header等配置.

    ###start跨域支持配置####
    add_header Access-Control-Allow-Origin '*';
    add_header Access-Control-Allow-Headers Accept,Origin,X-Requested-With,Content-Type,If-Modified-Since,Last-Modified,Content-Length,Content-Range,Range,Content-Description,Content-Disposition;
    add_header Access-Control-Allow-Methods GET,POST,PUT,DELETE,OPTIONS;
    add_header Access-Control-Request-Headers Content-Disposition;
    add_header Access-Control-Allow-Credentials true;

    ###end ###

    server {
        listen       80;
        server_name  127.0.0.1;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            root   html;
            index  index.html index.htm;
        }

        #自定义本地路径,代理转发请求
        location /pdm        {
            proxy_pass   http://c2.zhuzher.com/pdm;
       }

    }

    server {
        listen       8081;
        server_name  127.0.0.1;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            root   html;
            index  index.html index.htm;
        }

        #自定义本地路径,代理转发请求
          location /pdm        {
            proxy_pass http://c2.zhuzher.com/pdm;
            charset  utf-8;
            #   proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        }

    }

注意

项目里面直接调用配置的8081端口就可以了:

api.get('//localhost:8081/pdm/user/login',data)

注意这里还有一点需要注意,如果Content-Type是 application/json的话是无法发送跨域请求的,这里提供一种解决办法,就是接口前端请求type改成

'Content-Type':'text/plain'
发送数据转成字符串:

JSON.stringify(data)

后端接口用String接受数据,然后再转成对象就可以了:

 @PostMapping("/distributeBatch")
    public ResMsg distributeSaleBatch(@RequestBody String params){
        System.out.println(params);
        //Integer user_id, Integer customer_id
        //Gson 字符串转对象
        List<Map<String, Integer>> fromJson = new Gson().fromJson(params, new TypeToken<List<Map<String, Integer>>>() {
        }.getType());
        System.out.println(new Gson().toJson(fromJson));
        return registeredCustomerService.distributeSaleBatch(fromJson);
    }