@ConfigurationProperties根據型別校驗和管理application中的bean。

Spring Boot 使用一些鬆的規則來繫結屬性到@ConfigurationProperties bean 並且支援分層結構（hierarchical structure）。
開始建立一個@ConfigurationProperties bean:

@ConfigurationProperties(locations = "classpath:mail.properties", 
                         ignoreUnknownFields = false, 
                         prefix = "mail")
public class MailProperties { 
  public static class Smtp {  
    private boolean auth;  
    private boolean starttlsEnable;  
    // ... getters and setters 
  }
  @NotBlank private String host;
  private int port;  
  private String from; 
  private String username;
  private String password; 
  @NotNull private Smtp smtp; 
  // ... getters and setters
}
 

 mail.properties 檔案

mail.host=localhost
mail.port=25
mail.smtp.auth=false
mail.smtp.starttls-enable=false
[email protected]
mail.username=
mail.password=

@Configuration
@ConfigurationProperties(locations = "classpath:mail.properties", 
                         prefix = "mail")
public class MailConfiguration { 
  public static class Smtp {
    private boolean auth;
    private boolean starttlsEnable;
    // ... getters and setters
 }

 @NotBlank private String host; 
 private int port;
 private String from; 
 private String username;
 private String password; 

 @NotNull private Smtp smtp; 
 // ... getters and setters  

 @Bean public JavaMailSender javaMailSender() {
  // omitted for readability
 }
}
 

方案2

我們和上面例子一樣註解屬性，然後用 Spring的@Autowire來注入 mail configuration bean:

@Configuration
@EnableConfigurationProperties(MailProperties.class)
 public class MailConfiguration { 
    @Autowired private MailProperties mailProperties; 

    @Bean public JavaMailSender javaMailSender() {
      // omitted for readability
    }
 }

org.springframework.beans.factory.NoSuchBeanDefinitionException:

 No qualifying bean of type [demo.mail.MailProperties] found for dependency:

 expected at least 1 bean which qualifies as autowire candidate for this dependency.

 Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

不過也有采用讀檔案的方式去做的

new ConfigTool().getClass().getResourceAsStream("/config.properties");

spring.profiles.active=testdb

然後通過這個註解去執行