什么是AOP？这种在运行时，动态地将代码切入到类的指定方法、指定位置上的编程思想就是面向切面的编程。

Written by Zhong Wei

什么是AOP？这种在运行时，动态地将代码切入到类的指定方法、指定位置上的编程思想就是面向切面的编程。

https://www.zhihu.com/question/24863332

Fix the ‘Too Many Open Files’ Error in a systemd service in Linux

Written by Zhong Wei

In short:

Change the service file, and add two lines after [Service] line, 

[Service]
LimitNOFILE=65535
LimitNOFILESoft=65535

If you want to know more, read the Reference

SELinux sucks?! Safety always means inconvenient, right!

Written by Zhong Wei

Just record what I made Nginx working with a project located in someone's HOME directory on a Linux machine with SELinux on.

  1. Nginx seems working normally, but it actually Didn't listen to a non-80 port at all. If it reports ValueError: Port tcp/8081 already defined, replace -a with -m.

    semanage port -a -t http_port_t -p tcp 8081

Reference1 Reference2

  1. telnet localhost 8081 works, but telnet 192.168.168.168 8081 from another machine not working!

    firewall-cmd --permanent --add-port=8081/tcp
    firewall-cmd --reload

  2. Everything seems working good, but when you visit your site, Nginx just gives you a 403! You should ensure Nginx can access your project directory, everyone knows that, but is not enough when SELinux is on.

    setsebool -P httpd_enable_homedirs 1
    setenforce 0
    systemctl restart nginx
    systemctl daemon-reload

Reference

Caution: Javascript A || B expression is handy, but it also can cause tricky bug

Written by Zhong Wei

I had written the following code in a project

   ...
   return s && s.value || null

It works well for some days until a colleague did some code refactoring. In the beginning, s.value is a string value, and an empty string is not a valid value, so the code works well. After the refactoring, s.value became an integer, and this time 0 is a valid value. So you can imagine when s.value === 0 the code above will return null instead of 0. It caused a bug!

Therefore please use the"A || B" expression with caution!

微信浏览器内H5活动页调起小程序, 服务器端开发备忘

Written by Zhong Wei
  1. 公众平台设置H5静态页服务器IP白名单
  2. 上传验证文件到根目录（一定要先做好这一步才能做下一步啊
  3. 公众平台设置域名白名单
  4. 服务器端配置公众平台 appId, appSecret
  5. 缓存针对此appId的 accessToken 和 jsapi_ticket
  6. 服务器端生成签名.....参数一定要按字典序！（坑）