SpringBoot读取配置文件的6种实现方式

student:
  name: 张三
  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 配置获取 name:{},age:{}",name,age);
    }

}

@Value("${一级属性名.二级属性名...}")

//可以使用各种类型的默认值，包括字符串、数字、布尔值等
@Value("${student.name:aopmin}")
private String name;

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

//表示一个空字符串作为默认值
@Value("${student.name:}")
private String name;

/*
@Value注解被用于构造函数参数、setter方法和普通方法上。容器初始化时，会将配置属性的值作为参数传递到构造函数、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;

/**
 * 参数配置类   (需要提供setter方法)
 */

//将这个类与配置文件前缀为student的配置绑定,然后把yml、properties中关于student的配置信息注入到当前类的成员变量中
@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("读取配置: 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核心的环境配置接口，它提供了一些方法用于访问应用程序配置属性。
 * 包括系统属性、操作系统环境变量、命令行参数、以及配置文件中定义的属性等等
 */

@Slf4j
@SpringBootTest
public class EnvironmentTest {

    @Resource
    private Environment env;

    @Test
    public void test() {
        String name = env.getProperty("student.name");
        // 逻辑处理...(也可以控制某一个bean是否生效)
        log.info("Environment配置读取: 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配置读取: name:{}", name);
    }

    @Override
    public void setEnvironment(Environment environment) {
        // 逻辑处理...(也可以控制某一个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;

/**
 * 绑定自定义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配置读取 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读取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"));//自定义yml文件

        //Objects.requireNonNull()方法的作用是如果对象为空，则抛出空指针异常，否则返回对象本身。
        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("读取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() {
        // 配置对象
        Properties props = new Properties();
        InputStreamReader input = null;
        try {
            // 输入流 （字节流转字符流）
            input = new InputStreamReader(
                    //通过类加载器来获取指定路径下的资源文件，并返回一个InputStream对象
                    this.getClass().getClassLoader().getResourceAsStream("student.properties"), StandardCharsets.UTF_8); //指定编码格式

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

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

}