The parameters that can be added to Configuration are mainly the following three categories:
Added parameter priority
Program arguments > VM options > Environment variable > 系统默认值1、Program arguments
Program arguments is the string array args[] passed into the main method
// Program arguments有两种类型，一种是以--key=value的形式；一种是直接写value
// 参数之间空格分隔
--mode=debug test
Add method
access method
2、VM options
VM options are actually the runtime environment variables we need in the program. They need to start with -D or -X or -XX, and each parameter is separated by a space.
The most commonly used method is -Dkey=value to set system property values, such as -Dspring.profiles.active=dev
Add method
// -D开头 + 参数名 = 参数值
// = 两侧没有空格
// 不同参数之间空格分隔
// 如下所示我们增加两个参数 Env 和 Name
-DEnv=prod -DName=admin
access method
// System.getProperty("参数名")
System.getProperty("Env");
System.getProperty("Name");3、Environment variables
Environment variables have no prefix
Add method
// 参数名=参数值
// 多个参数之间使用分号分隔（注意这里不是用空格分隔）
password=123456;name=admin
access method
// System.getenv("参数名")
System.getenv("password");
System.getenv("name");Parameter Description:
1. VM options
VM options are actually the runtime environment variables we need in the program. They need to start with -D or -X or -XX, and each parameter is separated by a space.
The most commonly used method is -Dkey=value to set system property values, such as -Dspring.profiles.active=dev3
二、Program arguments
Program arguments is the string array args[] we passed into the main method, which usually starts with --, such as --spring.profiles.active=dev3
Equivalent to -Dspring.profiles.active=dev3. If both exist, the Program arguments configuration takes precedence.
三、Environment variables
Environment variables have no prefix and have lower priority than VM options. That is, if VM options has a variable with the same key as the variable in Environment variable, the VM options will prevail.
