Explain in detail the common ways for SpringBoot to read properties files under resource directory

Personal understanding

In enterprise development, we often need to customize 1 global variable/unmodifiable variable or parameter to solve a large number of variable duplication problems. When this global variable is needed, we only need to read it from the configuration file. According to the common situation in development, it can be divided into the following two situations, namely:

The configuration file is a custom parameter in the default application. properties file for SpringBoot Load custom parameters in the custom properties file, such as the custom parameters of xxx. properties

Load the default application. properties for SpringBoot

Preparatory work

server.port=8081

#  Custom parameters -> It's all person. Form of variable name 

person.id=1
person.name=szh

# list/set/ Array -> Two ways of writing 
person.hobby=play,read,write
person.family[0]=father
person.family[1]=mother

# map-> Two ways of writing 
person.map.key1=value1
person.map[key2]=value2

# Entity Object ->Pet Entity class 
person.pet.type=dog
person.pet.name= Prosperous wealth 

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.io.Serializable;

@NoArgsConstructor
@AllArgsConstructor
@Data
public class Pet implements Serializable {
 private String type;
 private String name;
}

Mode 1: @ ConfigurationProperties

In development, if you get all the parameters beginning with xxx, you recommend using the first method, and if you get a single parameter, you recommend using the second method to get parameters.

import com.szh.test.entity.Pet;
import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.Map;

@Component
@ConfigurationProperties(prefix = "person")
@Data
public class PersonConfig {
 private int id;
 private String name;
 private List hobby;
 private String[] family;
 private Map map;
 private Pet pet;

}

Test using code:

@Autowired
 private PersonConfig personConfig;

 @RequestMapping("/hello1")
 public void hello1() {
 System.out.println(personConfig.getFamily());
 System.out.println(personConfig.getHobby());
 System.out.println(personConfig.getMap());
 System.out.println(personConfig.getId());
 System.out.println(personConfig.getName());
 System.out.println(personConfig.getPet().getName());
 }

Mode 2: @ Value

@Value("${person.id}")
 private int id;
 @Value("${person.name}")
 private String name;
 @Value("${person.hobby}")
 private List hobby;
 @Value("${person.family}")
 private String[] family;
 @Value("${person.map}")
 private Map map;
 @Value("${person.pet}")
 private Pet pet;

Mode 3: Use Environment to get

@Autowired
 private Environment env;

 @RequestMapping("/hello1")
 public void hello1() throws UnsupportedEncodingException {

 String id = env.getProperty("person.id");
 //  Chinese 
 String name = new String(env.getProperty("person.name").getBytes("ISO-8859-1"), "UTF-8");
 List hobby = new ArrayList();
 hobby.add(env.getProperty("person.hobby[0]"));
 hobby.add(env.getProperty("person.hobby[1]"));
 String[] family;
 Map<String,String> map = new HashMap<String,String>();
 map.put("key1", env.getProperty("person.map.key1"));
 map.put("key2", env.getProperty("person.map.key2"));

 Pet pet = new Pet(env.getProperty("person.pet.type"),env.getProperty("person.pet.name"));
 }

Load a custom properties file

Preparation: Create a new custom configuration file szh. properties in the resource/directory

person.id=1
person.name=szh

# list/set/ Array -> Two ways of writing 
person.hobby=play,read,write
person.family[0]=father
person.family[1]=mother

# map-> Two ways of writing 
person.map.key1=value1
person.map[key2]=value2

# Entity Object 
person.pet.type=dog
person.pet.name= Prosperous wealth 

Mode 1: @ PropertySource + @ ConfigurationProperties

@Component
@PropertySource(value = "classpath:szh.properties")
@ConfigurationProperties(prefix = "person")
@Data
public class PersonConfig {
 private int id;
 private String name;
 private List hobby;
 private String[] family;
 private Map map;
 private Pet pet;

}

Mode 2: @ PropertySource + @ Value

@Component
@PropertySource(value = "classpath:szh.properties")
@Data
public class PersonConfig {
 @Value("${person.id}")
 private int id;
 @Value("${person.name}")
 private String name;
 @Value("${person.hobby}")
 private List hobby;
 @Value("${person.family}")
 private String[] family;
 @Value("${person.map}")
 private Map map;
 @Value("${person.pet}")
 private Pet pet;

}

Mode 3: Properties Load

// Read the resource configuration file 
 InputStream is = Bean.class.getClassLoader().getResourceAsStream("szh.properties");
 prop = new Properties();
 String className = "person.name";// Can be used as 1 Variables of functions 
 try {
  prop.load(is);
  String pathName = prop.getProperty(className);
 } catch (Exception e) {
  throw new RuntimeException("xxxx");
 }