解决跨域的几种方式

nginx

在location拦截目录下，处理options信令

 if ($request_method = 'OPTIONS') {
                        add_header 'Access-Control-Allow-Origin' '*';
                        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS, DELETE, PUT';
                        add_header 'Access-Control-Allow-Headers' 'origin, content-type, accept, authorization,key,mobile,token,clienttype,version,Content-Type,if-none-match,x-3gpp-intended-identity';
                        add_header 'Content-Length' 0;
                        return 204;
                }
 }

服务端

拦截options请求，返回一系列Access-*

public abstract class PublicServlet extends HttpServlet {
    private static final Logger LOGGER = LoggerFactory.getLogger(PublicServlet.class);

    public void process(HttpServletContext ctx) throws Exception {
        HttpServletRequest request = ctx.getRequest();
        LOGGER.info("req url is {}", request.getRequestURL());
        HttpServletResponse response = ctx.getResponse();
        response.setHeader("Access-Control-Allow-Origin", "*");

        String method = request.getMethod().toLowerCase();
        switch (method) {
            case "post":
                doPost(request, response);
                break;
            case "get":
                doGet(request, response);
                break;
            case "delete":
                doDelete(request, response);
                break;
            case "put":
                doPut(request, response);
                break;
            case "options":
                doOptions(request, response);
                break;
            default:
                break;
        }
    }

    @Override
    protected void doOptions(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doOptions(req, resp);
        resp.setHeader("Access-Control-Allow-Origin", "*");
        resp.setHeader("Access-Control-Allow-Methods", "GET,POST,PUT,DELETE,OPTIONS");
        resp.setHeader("Access-Control-Allow-Headers", req.getHeader("access-control-request-headers"));
    }