前端跨域问题

以前项目中遇到过这个问题，当时解决了，今天又遇到这个问题，一时想不起来了，翻了上个项目的代码，才解决了问题。现在记录下来，防止再忘记了。
这是用后端的方式解决跨域问题，就是在过滤器或者拦截器中加上一段：

response.setHeader("Access-Control-Allow-Origin", "*");
response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
response.setHeader("Access-Control-Max-Age", "3600");
response.setHeader("Access-Control-Allow-Headers", "x-requested-with");

这是完整的拦截器preHandle方法：

@Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Headers", "x-requested-with");

        time.set(System.currentTimeMillis());

        logger.info("开始进入springmvc，线程id为" + Thread.currentThread().getId() + "，时间为" + time.get());

        return true;
    }