Question

我设置了环境变量

MY_APP_MY_MAP_A1=a
MY_APP_MY_MAP_A2=b
MY_APP_JUSTMAP_A1=a
MY_APP_JUSTMAP_A2=b

通过@ConfigurationProperties配置我的Spring Boot（2.1.7.RELEASE）应用程序：

@SpringBootApplication
@EnableConfigurationProperties(MyApp.MyProperties.class)
public class MyApp {

    public static void main(String[] args) {
        SpringApplication.run(MyApp.class, args);
    }

    @Bean
    public CommandLineRunner cmd(MyProperties props) {
        return args -> {
            System.out.println("myMap: " + props.getMyMap());
            System.out.println("justmap: " + props.getJustmap());
        };
    }

    @ConfigurationProperties(prefix = "my.app")
    @Getter
    @Setter
    static class MyProperties {
        private Map<String, String> myMap;
        private Map<String, String> justmap;
    }
}

当变量名称包含大写字母（用大写字母表示）时，设置Map<String,String>无效，否则一切正常：

myMap: null
justmap: {a1=a, a2=b}

有办法吗？

Answer 1

如果您关注以下环境。传递的变量

MY_APP_MYMAP_A1=a
MY_APP_MYMAP_A2=b
MY_APP_JUSTMAP_A1=a
MY_APP_JUSTMAP_A2=b

下面的代码显示了您的期望

@SpringBootApplication
@EnableConfigurationProperties(TestSpringBootApplication.MyProperties.class)
public class TestSpringBootApplication {

    public static void main(String[] args) {
        SpringApplication.run(TestSpringBootApplication.class, args);
    }

    @Bean
    public CommandLineRunner cmd(MyProperties props) {
        return args -> {
            System.out.println("myMap: " + props.getMyMap());
            System.out.println("justmap: " + props.getJustmap());
        };
    }

    @ConfigurationProperties(prefix = "my.app")   
    static class MyProperties {
        private Map<String, String> myMap;
        private Map<String, String> justmap;

        public Map<String, String> getMyMap() {
            return myMap;
        }
        public void setMyMap(Map<String, String> myMap) {
            this.myMap = myMap;
        }
        public Map<String, String> getJustmap() {
            return justmap;
        }
        public void setJustmap(Map<String, String> justmap) {
            this.justmap = justmap;
        }

    }

}

输出如下

2019-09-04 16:00:07.336  INFO 21204 --- [           main] c.e.demo.TestSpringBootApplication       : Started TestSpringBootApplication in 1.012 seconds (JVM running for 2.219)
myMap: {a1=a, a2=b}
justmap: {a1=a, a2=b}

有关此轻松绑定的规则的更多详细信息，请查看文档here

Answer 2

详细介绍Shailendra的答案，以下是docs的相关引文：

要将规范形式的属性名称转换为环境变量名称，可以遵循以下规则：

用下划线（_）替换点（。）。

删除所有破折号（-）。

转换为大写。

在骆驼的情况下，Spring Boot不会从环境变量加载Map

2 个答案: