注意：根据 Spring Boot 松散绑定，类的属性名称必须与外部属性的名称匹配
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| 格式：
user:
user_name: 赵云
user:
userName: 赵云
user:
USERNAME: 赵云
user:
user-name: 赵云
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以上四种命名可以自动绑定bean属性（properties配置文件也可用该注解）
激活 @ConfigurationProperties
我们除了在实体类上标注注解@ConfigurationProperties，还需要让spring容器知道它的存在，以便将其加载到应用程序上下文中。
所以，我们可以通过添加 @Component 注解让 Component Scan 扫描到
${user.userName}只支持属性的调用，不支持运算
测试
yml配置文件：
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| server:
port: 8081
user:
driver: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/javaweb_test?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai
userName: root
password: 111
girlFriend: {18: 范冰冰, 20: 迪丽热巴 }
hobby: [打球, 听歌, 打游戏]
address:
id: 1
desc: ${user.userName}在柳州
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Person实体类：
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| @Component
@ConfigurationProperties(prefix = "user")
public class Person {
private String driver;
private String url;
private String userName;
private String password;
private List<String> hobby;
private Map<Integer, String> girlFriend;
private Address address;
get/set方法...
}
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Address实体类：
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| public class Address {
private Integer id;
private String desc;
get/set...方法
}
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用法:
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| @Controller
public class BJController {
@Autowired
private Person person;
@RequestMapping("/test")
@ResponseBody
public Map<String, Object> test(){
Map<String, Object> map = new HashMap<>();
map.put("url", person.getUrl());
map.put("userName", person.getUserName());
map.put("password", person.getPassword());
map.put("className", person.getDriver());
map.put("GirlFriend", person.getGirlFriend());
map.put("hobby", person.getHobby());
map.put("id", person.getAddress().getId());
map.put("address", person.getAddress());
return map;
}
}
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输出 JSON格式：
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| {"password":"111","address":{"id":1,"desc":"root在柳州"},"className":"com.mysql.cj.jdbc.Driver","GirlFriend":{"18":"范冰冰","20":"迪丽热巴"},"id":1,"userName":"root","url":"jdbc:mysql://localhost:3306/javaweb_test?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai","hobby":["打球","听歌","打游戏"]}
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总结
- @ConfigurationProperties 和 @value 有着相同的功能,但是 @ConfigurationProperties的写法更为方便
- @ConfigurationProperties 的 POJO类的命名比较严格,因为它必须和prefix的后缀名要一致, 不然值会绑定不上, 特殊的后缀名是“driver-class-name”这种带横杠的情况,在POJO里面的命名规则是 下划线转驼峰 就可以绑定成功，所以就是 “driverClassName”