SpringBoot获取配置的几种方式

<!-- 核心启动器 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

server.port=9080
user.username=lin@j
user.age=20

@Component
@PropertySource(value = {"classpath:application.properties"})
public class PropertiesConfigOne {

    @Autowired
    private Environment environment;

    public void printProperties(){
        String userName = environment.getProperty("user.username");
        System.out.println("user.username：" + userName);
        String age = environment.getProperty("user.age");
        System.out.println("user.age：" + age);
    }
}

@Component
@PropertySource(value = {"classpath:application.properties"})
@ConfigurationProperties(prefix = "user")
public class PropertiesConfigTwo {

    //属性上不用使用@Value("${username}"), 这样会报错的
    private String username;
    private Integer age;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public void printProperties(){
        System.out.println("username：" + username);
        System.out.println("age：" + age);
    }

}

@Component
public class PropertiesConfigThree {

    public void printProperties() throws IOException {
        //PropertiesLoaderUtils是spring-core提供的
        Properties properties = PropertiesLoaderUtils.loadAllProperties("application.properties");
        System.out.println("user.username：" + properties.getProperty("user.username"));
        System.out.println("user.age：" + properties.getProperty("user.age"));
    }
}