前端和后端传参问题

1.前端和后端传参问题

1.接收Request Payload参数

1）方法2

前端若传递Request Payload参数，后端只能用实体类接收，并且要加上注解@RequestBody

2）方法2

 public ResTool account(HttpServletRequest  request,String userName, String password) {
        ServletInputStream is;
        try {
            is = request.getInputStream();
            int nRead = 1;
            int nTotalRead = 0;
            byte[] bytes = new byte[10240];
            while (nRead > 0) {
                nRead = is.read(bytes, nTotalRead, bytes.length - nTotalRead);
                if (nRead > 0) {
                    nTotalRead = nTotalRead + nRead;
                }
            }
            // 此处可以接收
            String str = new String(bytes, 0, nTotalRead, "utf-8");
            return ResTool.build();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return ResTool.build();
    }

2.跨域解决办法

关于CORS机制的详细解释这里就不多做介绍了，相关的文档资源也很多，推荐查看MDN上“HTTP访问控制（CORS）”文章的讲解。这里主要记录一下，我在nginx上做好配置，已经添加好了“Access-Control-Allow-Origin”头部之后，跨域依旧报错的问题。

如下是nginx的配置片段，已经加好了相应的头部：原因在于此接口的返回码是400，而按照nginx官方文档针对add_header指令的说明，上面的配置，“add_header”指令默认只会给2xx和3xx开头的部分http返回码加上头部，除此返回码之外的其他响应是不会加上对应头部的。

    location / {
            #proxy_pass http://127.0.0.1:9090/;
            proxy_pass http://127.0.0.1:8885/;
        //把OPTIONS的请求转成2xx
        if ($request_method = 'OPTIONS') {
        return 204;
    }
            add_header "Access-Control-Allow-Origin" "*" always;
            add_header "Access-Control-Allow-Credentials" "true" always;
            add_header "Access-Control-Allow-Methods" "GET,POST,HEAD,PUT,DELETE,OPTIONS" always;
            add_header "Access-Control-Allow-Headers" "access-control-allow-origin, authority, content-type, version-info, X-Requested-With" always;
            proxy_set_header Host $host:$server_port;  
            proxy_set_header X-Real-IP $remote_addr;  
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;  
            proxy_set_header X-Request-Proxy-key proxyWS;
            proxy_connect_timeout 100;
            proxy_send_timeout 100;
            proxy_read_timeout 100;
        }