Fundamentals - configuration file analysis

Copy module

• Delete the file of the previous project , Leave only pom.xml and src file
• modify pom In the document artifactId Consistent with the new project
• If not modified name Label words , Try to put name Labels and description All labels are deleted
• Just keep the backup

Attribute configuration (application.properties)

• Each configuration corresponds to technology , If you don't quote a certain technology , There will be no code prompt in the configuration file
• Official configuration file

#  Server port configuration 
server.port=80

#  modify banner
#spring.main.banner-mode=console
#  modify banner chart 
#spring.banner.image.location=ysg.jpg

#  journal 
logging.level.root=info

There are three types of configuration files

• When three coexist properties > yml > yaml

• The same attribute will take priority , Different configurations will keep the configuration

  properties
  yml
  yaml

Add configuration file

• Configuration file automatic code prompt

yml The configuration file

• advantage

  Easy to read
  Easy to interact with scripts
  Data core , Data over format

• Rule of grammar

  Case sensitive
  Attribute hierarchies are described in multiple lines , End each line with a colon
  Use indentation to indicate hierarchy , Align left side of the same level , Only Spaces are allowed
  Add a space before the attribute value （ Use between attribute name and attribute value The colon + Space As a division ）

  # Notation

• yml Various data formats in the file

#  Server port configuration 
server:
  port: 81

country: china

party: true

birthday: 1949-10-01

null: ~

#  An object 
user:
  name: ssc
  age: 23

#  Multi level objects 
a:
  b:
    c:
      d: 5

#  Array 
likes:
  - game
  - music
  - sleep
  -
likes1: [game,music,sleep]

#  An array of objects 
users:
  -
    name: zhangsan
    age: 18
  -
    name: wangwu
    age: 23

users1:
  - name: zhangsan
    age: 18
  - name: wangwu
    age: 23

users2: [{
    name:zhangsan,age:18},{
    name:lisi,age:17}]

Read yml File data

• annotation @Value coordination SpEL Read single data , Multiple data are read hierarchically

    //  read yml Single data of data in 
    @Value("${country}")
    private String country1;
    //  object 
    @Value("${user.name}")
    private String name1;
    //  Array 
    @Value("${likes[1]}")
    private String likes1;
    //  Array objects 
    @Value("${users[0].age}")
    private String age1;
    //  Port number 
    @Value("${server.port}")
    private String port;

Variable references & Escape character

#  Variable references 
baseDir: c:\windows

tempDir: ${
    baseDir}\temp

#  Escape character 
tempDir1: "${baseDir}\temp \t1 \t2 \t3 \t4"

//  Variable references 
@Value("${tempDir}")
private String tempDir;
//  Escape character 
@Value("${tempDir1}")
private String tempDir1;

Read all yml attribute

• Use Environment Object encapsulates all information
• Use @Autowired Automatically assemble data to Environment In the object
• env.getProperty(“server.port”) Read different properties

//  Read all yml attribute , Automatic assembly 
    @Autowired
    private Environment env;

 System.out.println(env.getProperty("server.port"));
 System.out.println(env);

Read yml Reference data type （ Commonly used ）

• yml Define an object data type

#  Reference data types that need to be read 
datasource:
  driver: com.mysql.cj.jdbc.Driver
  url: jdbc:mysql://localhost:3306/mybatis
  username: root
  password: 123456

• Specify the corresponding class

// spring Managed Bean
@Component
//  Specify the loaded yml A property of 
@ConfigurationProperties(prefix = "datasource")
@Data
public class MyDataSource {
    
    private String driver;
    private String url;
    private String username;
    private String password;
}

• Output

System.out.println(myDataSource);