Spring Boot中的属性绑定的实现

@Component
@ConfigurationProperties(prefix = "kaka.cream.mail-a",ignoreUnknownFields = false)
public class MailPropertiesA {
  private String name;
  private String sex;
  private Integer age;

@Bean
  @ConfigurationProperties(prefix = "kaka.cream.mail-b",ignoreUnknownFields = false)
  public MailPropertiesB mailPropertiesB(){
    MailPropertiesB b = new MailPropertiesB();
    return b;
  }

@Data
@ConfigurationProperties(prefix = "kaka.cream.mail-c",ignoreUnknownFields = false)
public class MailPropertiesC {
  private String name;
  private String sex;
  private Integer age;
}

@EnableConfigurationProperties(MailPropertiesC.class)
public class GomvcApplicationTests {

//判断是否包含键值
boolean containsProperty(String key);
//获取属性值，如果获取不到返回null
String getProperty(String key);
//获取属性值，如果获取不到返回缺省值
String getProperty(String key, String defaultValue);
//获取属性对象
<T> T getProperty(String key, Class<T> targetType);

//绑定对象
MailPropertiesC propertiesC = Binder.get(environment).bind("kaka.cream.mail-c", Bindable.of(MailPropertiesC.class)).get();
//绑定Map
Map<String,Object> propMap = Binder.get(environment).bind("fish.jdbc.datasource",Bindable.mapOf(String.class, Object.class)).get();
//绑定列表
List<String> list = Binder.get(environment).bind("kaka.cream.list",Bindable.listOf(String.class)).get();
//转换以及默认值
String datestr = (String) Binder.get(environment).bind("kaka.cream.date",Bindable.of(String.class))
        .map(String::toUpperCase)
        /** .map(new Function(){
          @Override
          public Object apply(Object o) {
            String str = (String)o;
            return str.toUpperCase();
          }
        })**/
        .orElse("bad date string");
        
//绑定过程回调函数，高度定制
LocalDate str = Binder.get(environment).bind("kaka.cream.date", Bindable.of(LocalDate.class), new BindHandler() {

      @Override
      public <T> Bindable<T> onStart(ConfigurationPropertyName name, Bindable<T> target,
                  BindContext context) {
        log.info("绑定开始{}",name);
        return target;
      }
      @Override
      public Object onSuccess(ConfigurationPropertyName name, Bindable<?> target, BindContext context, Object result) {
        log.info("绑定成功{}",target.getValue());
        return result;
      }

      @Override
      public Object onFailure(ConfigurationPropertyName name, Bindable<?> target, BindContext context, Exception error) throws Exception {
        log.info("绑定失败{}",name);
        return "没有找到匹配的属性";
      }

      @Override
      public void onFinish(ConfigurationPropertyName name, Bindable<?> target, BindContext context, Object result) throws Exception {
        log.info("绑定结束{}",name);
      }
    }).get();