import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 @SpringBootApplication
 public class App {
      public static void main(String[] args) {
         SpringApplication app = new SpringApplication(App.class);
         ConfigurableApplicationContext context = app.run(args);
         System.out.println(context.getEnvironment().getProperty("jdbc.pwd"));
 9         context.close();
     }
 }

apllication.yml 放置在classpath路径下1 jdbc:2   pwd: 123456  #冒号和数字之间有一个空格，没有否则获取失败，pwd前面有缩进两个字符

ps:版本spring-4.3.2-release,springboot-1.4