According to news on November 29, according to the official website of the Chinese Academy of Sciences, recently, the Changchun Institute of Optics, Fine Mechanics and Physics of the Chinese Academy of Sciences developed a large-scale laser communication calibration equipment for Beidou Global System to complete the satellite-to-ground high-speed downlink laser communication test.

The equipment has completed various test contents for the high-orbit and medium-orbit satellite terminals, and has realized the two-way tracking of beacons and signals, adaptive correction, uplink and downlink communication, and calibration of the satellite terminal parameters.

Because laser communication has the advantages of high speed and high confidentiality, it has become one of the important technical means in satellite data relay, high-speed data transmission, and satellite communication networks. Large-aperture laser communication calibration equipment is a must in laser communication networks. Device.

According to reports, the Beidou laser communication calibration ground equipment is the first time that Changchun Institute of Optics and Mechanics has applied adaptive technology to the field of satellite-to-ground laser communication. The wavefront correction accuracy is better than λ/8 (λ=1550nm), and the coupling efficiency before and after correction has been greatly improved. , Under the conditions of urban atmospheric turbulence, the satellite-to-ground downlink coherent optical communication is realized. The device can be used in vehicles to facilitate the deployment of mobile stations. Its first test has realized the second communication of coarse tracking between satellites in the same high orbit on the ground.

At present, Beidou laser communication standard calibration ground equipment has completed many test tasks of ground-to-medium orbit satellites and high-orbit satellites.

前提条件

对抽象类和接口有了基本概念的了解。大部分文章整的比较复杂，虽然说得对，但还是不好区分。

核心概要总结如下：

-- 抽象类 跟普通类没啥大区别，只是多了抽象方法。不能new。 属于顶层设计，定义出共有的属性和方法。
含有抽象方法一定是抽象类。

-- 接口，更严格，不能new
只能定义常量 public static final，默认的可忽略
只能有抽象方法，不能有构造方法，默认就是public abstract 可以忽略
jdk1.8之后，放宽条件，可以 defalut关键字声明普通方法，静态方法

使用场景：

抽象类，一般用于含有共有属性及功能的抽取，如人是一个抽象类，下面还有男人 女人等，人都有公用的属性和方法。java是单继承

接口，可以多实现、继承，解耦，多态。 动物>> 狗 猫

综上，大概就是这个样子，相比其它文字的长篇大论是不是清晰很多，只要理解核心即可。

解决办法：
Remove this line from the build.gradle on the specified project (移除build.gradle的这个配置）

apply from: 'https://raw.github.com/twotoasters/gradle-mvn-push/master/gradle-mvn-push.gradle'

library has gradle tasks for uploading to the Maven repository that require some properties to be set for the gradle environment, in your project you don't need/want that.

MyBatis的缓存分为一级缓存和二级缓存(全局缓存) ，缓存示意图如下图所示。默认情况下，一级缓存是开启的，且不能被关闭。
一次数据库 SqlSession会话中，执行多次查询条件完全相同的SQL，MyBatis提供了一级缓存的方案优化这部分场景，如果是相同的SQL语句，会优先命中一级缓存，避免直接对数据库进行查询，提高性能。

二级缓存（全局缓存）开启后，同一个namespace下的所有操作语句，都影响着同一个Cache，即二级缓存被多个SqlSession共享，是一个全局的变量。
当开启缓存后，数据的查询执行的流程就是 二级缓存 -> 一级缓存 -> 数据库。

使用try_files属性

location / {
  root   /app/web;
  try_files $uri $uri/ @router; #检测文件是否存在不存在则重定向到首页目录    防止404
  index  index.html index.htm;
  #proxy_set_header        Host $host;
  #nginx非80端口处理 加上 :$server_port
   client_max_body_size 10m;
   client_body_buffer_size 128k;
}
location @router {
   rewrite ^.*$ /index.html last;
}

在项目的子路由下刷新页面出现了404，这是因为刷新页面时访问的资源在服务端找不到，因为vue-router设置的路径不是真实存在的路径。
当用户请求 http://localhost/example 时，这里的 $uri 就是 /example。
try_files 会到硬盘里尝试找这个文件。如果存在名为 /$root/example（其中 $root 是项目代码安装目录）的文件，就直接把这个文件的内容发送给用户。