Configuration coverage

At present, our parameter configuration is mainly based on configuration files: you can refer to PropertiesUtils,

But usually important parameters will be injected through the form of Java runtime virtual machine parameters, so we need to support this way of parameter injection. At the same time, because different ways of parameter injection have different priorities, we need to achieve configuration coverage. There are two main situations at present, SystemProperties and LocalFile. The priority of SystemProperties should be the highest, followed by LocalFile (that is, our various configuration files, such as master.properties).

for example:
1: Configure master.max.cpuload.avg=-1 in master.prperties

2: Java runtime virtual machine parameters -Dmaster.max.cpuload.avg=1

3:PropertiesUtils.get("master.max.cpuload.avg") = 1