student:
  name: 張三
  age: 20

@SpringBootTest
@Slf4j
public class ValueTest {
    @Value("${student.name}")
    private String name;

    @Value("${student.age}")
    private Integer age;

    @Test
    public void test() {
    log.info("@Value 配置獲取 name:{},age:{}",name,age);
    }

}

@Value("${一級屬性名.二級屬性名...}")

//可以使用各種類型的默認值，包括字符串、數(shù)字、布爾值等
@Value("${student.name:aopmin}")
private String name;

@Value("${student.age:18}")
private Integer age;

//表示一個空字符串作為默認值
@Value("${student.name:}")
private String name;

/*
@Value注解被用于構造函數(shù)參數(shù)、setter方法和普通方法上。容器初始化時，會將配置屬性的值作為參數(shù)傳遞到構造函數(shù)、setter方法和普通方法中。
*/

@Component
public class MyBean {

    private String myProperty;

    @Autowired
    public MyBean(@Value("${my.property}") String myProperty) {
        this.myProperty = myProperty;
    }

    @Value("${another.property}")
    public void setAnotherProperty(String anotherProperty) {
        // do something with anotherProperty...
    }

    @Value("${yet.another.property}")
    public void processValue(String value) {
        // do something with value...
    }

}

student:
  name: zhangsan
  age: 18

package cn.hk.pojo;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

/**
 * 參數(shù)配置類   (需要提供setter方法)
 */

//將這個類與配置文件前綴為student的配置綁定,然后把yml、properties中關于student的配置信息注入到當前類的成員變量中
@Component
@Data
@ConfigurationProperties(prefix = "student")
public class StudentProperties {
    private String name;

}

@SpringBootTest
public class ConfigurationPropertiesTest {

    @Autowired
    private StudentProperties studentProperties;

    @Test
    public void test() {
        System.out.println("讀取配置: name==="+studentProperties.getName());
    }

}

student:
  name: zhangsan
  age: 18

package cn.hk.test;

import lombok.extern.slf4j.Slf4j;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.core.env.Environment;
import javax.annotation.Resource;

/**
 * Environment是springboot核心的環(huán)境配置接口，它提供了一些方法用于訪問應用程序配置屬性。
 * 包括系統(tǒng)屬性、操作系統(tǒng)環(huán)境變量、命令行參數(shù)、以及配置文件中定義的屬性等等
 */

@Slf4j
@SpringBootTest
public class EnvironmentTest {

    @Resource
    private Environment env;

    @Test
    public void test() {
        String name = env.getProperty("student.name");
        // 邏輯處理...(也可以控制某一個bean是否生效)
        log.info("Environment配置讀取: name:{}", name);
    }
}

@Slf4j
@SpringBootTest
public class EnvironmentTest2 implements EnvironmentAware {

    private Environment env;

    @Test
    public void test() {
        String name = env.getProperty("student.name");
        log.info("Environment配置讀取: name:{}", name);
    }

    @Override
    public void setEnvironment(Environment environment) {
        // 邏輯處理...(也可以控制某一個bean是否生效)
        this.env = environment;
    }

}

student.id=1001
student.name=hello

package cn.hk.pojo;

import lombok.Data;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

/**
 * 綁定自定義properties配置
 */

@Data
@Configuration
@PropertySource(value = "classpath:student.properties", encoding = "UTF-8")
public class PropertySourcesConf {

    @Value("${student.id}")
    private Integer id;

    @Value("${student.name}")
    private String name;

}

@SpringBootTest
@Slf4j
public class PropertySourcesTest {

    @Resource
    private PropertySourcesConf propertySourcesConf;

    @Test
    public void test() {
       log.info("PropertySources配置讀取 id: {}", propertySourcesConf.getId());
       log.info("name: {}", propertySourcesConf.getName());
    }

}

file:
  type: text

package cn.hk.config;

import org.springframework.beans.factory.config.YamlPropertiesFactoryBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.core.io.ClassPathResource;
import java.util.Objects;

/**
 * 配置PropertySourcesPlaceholderConfigurer讀取yml配置
 */

@Configuration
public class MyYamlConfig {

    @Bean
    public static PropertySourcesPlaceholderConfigurer yamlConfigurer() {

        PropertySourcesPlaceholderConfigurer configurer = new PropertySourcesPlaceholderConfigurer();
        YamlPropertiesFactoryBean yaml = new YamlPropertiesFactoryBean();
        yaml.setResources(new ClassPathResource("student.yml"));//自定義yml文件

        //Objects.requireNonNull()方法的作用是如果對象為空，則拋出空指針異常，否則返回對象本身。
        configurer.setProperties(Objects.requireNonNull(yaml.getObject()));
        return configurer;

    }

}

@SpringBootTest
public class LoadYamlTest {

    @Value("${file.type}")
    private String fileType;

    @Test
    public void test() {
        System.out.println("讀取yaml配置:"+fileType);
    }

}

package cn.hk.test;

import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.Properties;


@SpringBootTest
public class CustomTest {

    @Test
    public void test() {
        // 配置對象
        Properties props = new Properties();
        InputStreamReader input = null;
        try {
            // 輸入流 （字節(jié)流轉字符流）
            input = new InputStreamReader(
                    //通過類加載器來獲取指定路徑下的資源文件，并返回一個InputStream對象
                    this.getClass().getClassLoader().getResourceAsStream("student.properties"), StandardCharsets.UTF_8); //指定編碼格式

            // 加載配置
            props.load(input);
        } catch (IOException e) {
            throw new RuntimeException(e);
        } finally {
            if (input!=null)
                try {
                    input.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
        }

        // 獲取配置
        System.out.println("id:" + props.getProperty("student.id") + ", name:" + props.getProperty("student.name"));
    }

}