Explain how SpringBoot annotations read configuration files in detail
- 2021-08-17 00:07:26
- OfStack
1. @ Value reads the values in the application. properties configuration file
application. properties configuration file
fileName=configName
PropertiesConfig class file
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component
public class PropertiesConfig {
// Pass @Value Annotation reading fileName Value of
@Value("${fileName}")
private String fileName;
public String getFileName() {
return fileName;
}
public void setFileName(String fileName) {
this.fileName = fileName;
}
}
Test
import com.model.PropertiesConfig;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@SpringBootTest
public class PropertiesConfigTest {
@Autowired
private PropertiesConfig propertiesConfig;
@Test
public void test(){
System.out.println(propertiesConfig.getFileName());// Result output: configName
assert "configName".equals(propertiesConfig.getFileName());
}
}
2. @ ConfigurationProperties reads values from multiple application. properties configuration files
application. properties file
database.username=root
database.password=root
DatabaseConfig class file
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
@Component
@ConfigurationProperties("database")
public class DatabaseConfig {
private String userName;
private String passWord;
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassWord() {
return passWord;
}
public void setPassWord(String passWord) {
this.passWord = passWord;
}
}
Test
import com.model.DatabaseConfig;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@SpringBootTest
public class DatabaseConfigTest {
@Autowired
private DatabaseConfig databaseConfig;
@Test
public void test(){
System.out.println("username = " + databaseConfig.getUserName() +", password = "+databaseConfig.getPassWord());// Result output: username = root, password = root
assert "root".equals(databaseConfig.getUserName());
assert "root".equals(databaseConfig.getPassWord());
}
}
3. @ PropertySource reads any configuration file
New property-source. properties configuration file
fileName=configName
database.username=root
database.password=root
PropertySourceConfig class file
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;
@Component
@PropertySource(value = {"classpath:property-source.properties"})
@ConfigurationProperties("database")
public class PropertySourceConfig {
@Value("${fileName}")
private String fileName;
private String userName;
private String passWord;
public String getFileName() {
return fileName;
}
public void setFileName(String fileName) {
this.fileName = fileName;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassWord() {
return passWord;
}
public void setPassWord(String passWord) {
this.passWord = passWord;
}
}
Test
import com.model.PropertySourceConfig;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@SpringBootTest
public class PropertySourceConfigTest {
@Autowired
private PropertySourceConfig propertySourceConfig;
@Test
public void test(){
assert "configName".equals(propertySourceConfig.getFileName());
System.out.println("fileName = " + propertySourceConfig.getFileName());// Result output: configName
assert "root".equals(propertySourceConfig.getUserName());
System.out.println(propertySourceConfig.getUserName());// Result output: root
assert "root".equals(propertySourceConfig.getPassWord());
System.out.println(propertySourceConfig.getPassWord());// Result output: root
}
}
Complete code link: read-config-file project address