java - 如何使用@Configuration定义运行时配置？

Question

我对 Spring 还很陌生，所以请耐心等待，如果您认为有必要，请随时建议使用正确的链接进行更多阅读。我正在使用一个类来定义我将调用的不同 Rest 端点的连接设置(用户名端口等)。所以我正在考虑将它们存储到 application.properties 中，如下所示:

twitter.username="a"
twitter.password="b"
twitter.host="www.twitter.com"
facebook.username="c"
facebok.password="d"
facebook.host="www.facebook.com"

现在我想定义一个类，它将采用所有前缀(例如“twitter”或“facebook”)并根据 applicaton.properties 中的相应属性返回配置类。

我正在考虑做类似以下的事情:

@Configuration    
@PropertySource("classpath:application.properties")
public class RESTConfiguration
{

    class RESTServer{
        public String username;
        public String password;
        public String host;
        private RESTServer(String username, String password, String host)
        {
             this.username = username;
             this.password = password;
             this.host = host;
        }

    }
    @Autowied
    private String ednpointName;

    @Bean
    public RESTServer restServer(Environment env)
    {
        return new RESTServer(env.getProperty(ednpointName + ".user"),
                env.getProperty(ednpointName + ".password"),
                env.getProperty(ednpointName+".host"));
    }
}

但它显然行不通，因为只有一个 Bean，而且我没有办法传递多个端点名称。帮助表示感谢!

Answer 1

更好的方法是使用工厂设计模式。大致如下:

@Configuration
@PropertySource("classpath:application.properties")
public class RESTConfiguration
{
        @Bean
        public RESTServerFactory restServer()
        {
            return new RESTServerFactory()
        }
}

public class RESTServer {
        public String username;
        public String password;
        public String host;
        private RESTServer(String username, String password, String host)
        {
             this.username = username;
             this.password = password;
             this.host = host;
        }
}

public class RESTServerFactory {
        @Autowired Environment env;

        public RESTServer getRESTServer(String endpointName)
        {
            return new RESTServer(env.getProperty(ednpointName + ".username"),
                env.getProperty(ednpointName + ".password"),
                env.getProperty(ednpointName+".host"));
        }
}

使用该工厂的示例:

@Autowired RESTServerFactory factory;

public RESTServer createServer(String endpoint) {
    return factory.getRESTServer(endpoint);
}