1. Introduction
Foreword:
One of the important thoughts of such a meteor as Spring is: the thought of configuration. So as to achieve the purpose of decoupling, many do not need to be hard-coded and can be completed with a configuration, which can be said to greatly improve the coding efficiency.
There are many ways to load configuration files supported by Spring . On the one hand, it expands flexibility, but on the other hand, it also brings greater complexity. Therefore, this article aims to use an article to solve the troubles of readers and friends, and sometimes it is also your troubles.
We know that SpringBoot supports three configuration files:
application*.yml
application*.yaml
application*.properties
Example:
Create application.yml and application.properties files in the Resources folder .
application.properties：
server.port=8001
application.yml ：
server: port: 7001
Run the program:
Through the running results, we can get:
These three configuration files have the highest priority of application*.properties . When application.properties and yml files coexist (under the same directory) ,
application.properties The priority is better, it will be read first, if it is not, then the value in yml will be read.
All the demo codes below are demonstrated in yml
Two, internal configuration file loading
What are the directories for loading internal configuration files?
We found the class ConfigFileApplicationListener to open in the IDE editor, and found that there are four default scan directories:
The corresponding four directories:
| path | Scan priority | |
| ./ | The config directory under the project root directory | 2 |
| ./config | The config directory under the project root directory | 1 |
| classPath:./ | The root directory under the build path | 4 |
| classPath:/config | The config directory under the compilation path | 3 |
Scanning sequence after project start:
-
- First go to the project root directory to find the configuration file in the config folder
- Go to the root directory to find the configuration file
- Go to resources to find the configuration file in the cofnig folder
- Go to resources to find the configuration file
For the above four directories, all configuration files will be loaded in the order of priority from low to high when SpringBoot is started, and high-priority configuration files will overwrite low-priority configuration files.
SpringBoot will load configuration files in all four locations. If the properties of the high-priority configuration file and the low-priority configuration file do not conflict, they will coexist and complement each other.
According to the above directory, we create the corresponding folder and the files under the folder in the project. The priority of the configuration file is:
Remarks:
The configuration files mentioned here are still in the project. In the end, they will be included in the jar package, so be careful.
1. If there is application.yml and application.properties in the same directory, application.properties is read first by default.
2. If the same configuration attribute is configured in multiple configuration files, the first read is used by default, and the later read does not overwrite the previous read.
3. When creating a SpringBoot project, the general configuration file is placed in the "resources directory of the project"
Three, external configuration file loading
Sometimes, the configuration information cannot be determined during the development process. For example, for projects developed for customers, customers need to customize the configuration according to their own conditions, such as database configuration, encryption key configuration and so on.
At this time, you need to put the configuration file outside to allow users to customize the configuration and deployment.
When SpringBoot is packaged, the ./config ./ two-level directories will not be packaged. This design is very clever, because it is not packaged, SpringBoot can load external configuration files.
SpringBoot supports storing configuration files externally. As long as the configuration file is placed in the same level directory of the jar package, or in the config folder under the same level , SpringBoot will read the configuration file here.
1. Now there is a SpringBoot packaging program (there is a configuration file application.yml in the default Resources folder):
application.yml configuration information:
server: port: 8001
Execute the command java -jar springboot-0.0.1-SNAPSHOT.jar, after the program is started, we can see that the startup port is 8001 that we configured:
2. At this time, we add the configuration file application.properties to the root directory :
server.port=8002
Execute the command java -jar springboot-0.0.1-SNAPSHOT.jar , after the program is started, the starting port is port 8002 configured in the application.properties configuration file
3. At this time, we add a folder and configuration file ./config/application.properties to the root directory
server.port=8003
Execute the command java -jar springboot-0.0.1-SNAPSHOT.jar , after the program is started, we find that the startup port is port 8003 configured in the application.properties configuration file in the root directory config folder
In this way, you only need to modify the configuration file information every time you modify it, and then restart the project, without repackaging. If you want to modify only the configuration file and it will take effect without restarting the project, you can consider using java to read the data in the configuration file.
Four, command line configuration mode
For example, in the method of java -jar , multiple properties are separated by spaces, and the properties in properties can basically be used. The usage is the method of property item = property value, for example:
java -jar springboot-0.0.1-SNAPSHOT.jar --server.port=8002 --server.context-path=/example
The above command line has two configurations server.port and server.context-path. It can be configured as required.
If our external configuration file does not want to be placed in the default location , we can use the --spring.config.location command to specify the directory of the configuration file .
Create a new test folder in the root directory and put the application.properties configuration file in it:
The content of the application.properties configuration file in the test folder :
server.port=8006
Execute the following command line to start the project:
java -jar springboot-0.0.1-SNAPSHOT.jar --spring.config.location=./test/application.properties
After the project is started, you can see that the port is the port configured in the application.properties configuration file in the test folder, and the configuration takes effect.
Original address:
https://www.cnblogs.com/wwj1992/articles/12569164.html