Spring 类型安全配置支持的环境

Question

我想在我的项目中使用类型安全配置（HOCON 配置文件），这有助于简单而有组织的应用程序配置。目前我正在使用普通的 Java 属性文件（application.properties），这在大项目上很难处理。

我的项目是 Spring MVC（不是 spring 引导项目）。有没有办法支持我的 Spring 环境（我正在注入我的服务）由类型安全配置支持。这不应该阻止我现有的环境使用像 @Value 注释，@Autowired Environment 等

我怎样才能以最少的努力和对代码的更改来做到这一点。

这是我目前的解决方案：求问有没有更好的办法

@Configuration
public class PropertyLoader{
    private static Logger logger = LoggerFactory.getLogger(PropertyLoader.class);

    @Bean
    @Autowired
    public static PropertySourcesPlaceholderConfigurer properties(Environment env) {
        PropertySourcesPlaceholderConfigurer pspc = new PropertySourcesPlaceholderConfigurer();

        Config conf = ConfigFactory.load();
        conf.resolve();
        TypesafePropertySource propertySource = new TypesafePropertySource("hoconSource", conf);

        ConfigurableEnvironment environment = (StandardEnvironment)env;
        MutablePropertySources propertySources = environment.getPropertySources();
        propertySources.addLast(propertySource);
        pspc.setPropertySources(propertySources);

        return pspc;
    }
}

class TypesafePropertySource extends PropertySource<Config>{
    public TypesafePropertySource(String name, Config source) {
        super(name, source);
    }

    @Override
    public Object getProperty(String name) {
        return this.getSource().getAnyRef(name);
    }
}

Answer 1

您创建一个 PropertySource class 如下，它与您的类似，不同之处在于您必须 return 值或 null 并且不让 lib 抛出丢失的异常

public class TypesafeConfigPropertySource extends PropertySource<Config> {

    private static final Logger LOG = getLogger(TypesafeConfigPropertySource.class);

    public TypesafeConfigPropertySource(String name, Config source) {
        super(name, source);
    }

    @Override
    public Object getProperty(String name) {
        try {
            return source.getAnyRef(name);
        } catch (ConfigException.Missing missing) {
            LOG.trace("Property requested [{}] is not set", name);
            return null;
        }
    }
}

第二步定义一个bean如下

    @Bean
    public TypesafeConfigPropertySource provideTypesafeConfigPropertySource(
        ConfigurableEnvironment env) {

        Config conf = ConfigFactory.load().resolve();
        TypesafeConfigPropertySource source = 
                          new TypesafeConfigPropertySource("typeSafe", conf);
        MutablePropertySources sources = env.getPropertySources();
        sources.addFirst(source); // Choose if you want it first or last
        return source;

    }

如果您想将属性自动装配到其他 bean，您需要使用对 propertysource bean 的注释 @DependsOn 以确保它首先被加载

希望对您有所帮助

Answer 2

我想我想出了一个比手动将 PropertySource 添加到属性来源稍微更惯用的方法。创建一个 PropertySourceFactory 并用 @PropertySource

引用它

首先，我们有一个 TypesafeConfigPropertySource 几乎与您拥有的相同：

public class TypesafeConfigPropertySource extends PropertySource<Config> {
    public TypesafeConfigPropertySource(String name, Config source) {
        super(name, source);
    }

    @Override
    public Object getProperty(String path) {
        if (source.hasPath(path)) {
            return source.getAnyRef(path);
        }
        return null;
    }
}

接下来，我们创建一个 PropertySource factory that returns that 属性 source

public class TypesafePropertySourceFactory implements PropertySourceFactory {

    @Override
    public PropertySource<?> createPropertySource(String name, EncodedResource resource) throws IOException {
        Config config = ConfigFactory.load(resource.getResource().getFilename()).resolve();

        String safeName = name == null ? "typeSafe" : name;
        return new TypesafeConfigPropertySource(safeName, config);
    }

}

最后，在我们的配置文件中，我们可以像任何其他 PropertySource 一样引用属性源，而不必自己添加 PropertySource：

@Configuration
@PropertySource(factory=TypesafePropertySourceFactory.class, value="someconfig.conf")
public class PropertyLoader {
    // Nothing needed here
}

Answer 3

Laplie Anderson 的回答有一些小改进：

如果找不到资源则抛出异常
忽略包含 [ 和 : 个字符的路径

TypesafePropertySourceFactory.java

import java.io.IOException;

import org.springframework.core.env.PropertySource;
import org.springframework.core.io.support.EncodedResource;
import org.springframework.core.io.support.PropertySourceFactory;

import com.typesafe.config.Config;
import com.typesafe.config.ConfigFactory;
import com.typesafe.config.ConfigParseOptions;
import com.typesafe.config.ConfigResolveOptions;

public class TypesafePropertySourceFactory implements PropertySourceFactory {

  @Override
  public PropertySource<?> createPropertySource(String name, EncodedResource resource)
      throws IOException {
    Config config = ConfigFactory
        .load(resource.getResource().getFilename(),
            ConfigParseOptions.defaults().setAllowMissing(false),
            ConfigResolveOptions.noSystem()).resolve();

    String safeName = name == null ? "typeSafe" : name;
    return new TypesafeConfigPropertySource(safeName, config);
  }
}

TypesafeConfigPropertySource.java

import org.springframework.core.env.PropertySource;

import com.typesafe.config.Config;

public class TypesafeConfigPropertySource extends PropertySource<Config> {
  public TypesafeConfigPropertySource(String name, Config source) {
    super(name, source);
  }

  @Override
  public Object getProperty(String path) {
    if (path.contains("["))
      return null;
    if (path.contains(":"))
      return null;
    if (source.hasPath(path)) {
      return source.getAnyRef(path);
    }
    return null;
  }
}

Answer 4

以上方法我都试过了，都失败了。我遇到的一个特殊问题是 bean 的初始化顺序。例如，我们需要 flyway 支持来获取一些来自类型安全配置的覆盖属性，其他属性也是如此。

正如 m-deinum 对我们的评论之一所建议的，以下解决方案有效，也依赖于其他答案的输入。通过在加载主应用程序时使用 ApplicationContextInitializer，我们确保道具在应用程序开始时加载并正确合并到 "env" 中：

import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.annotation.Import;

@SpringBootConfiguration
@Import({MyAppConfiguration.class})
public class MyApp {

    public static void main(String[] args) {
        new SpringApplicationBuilder(MyApp.class)
            .initializers(new MyAppContextInitializer())
            .run(args);
    }
}

ContextInitializer 看起来像这样：

import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;

public class MyAppContextInitializer implements
    ApplicationContextInitializer<ConfigurableApplicationContext> {

    @Override
    public void initialize(ConfigurableApplicationContext ac) {    
        PropertiesLoader loader = new PropertiesLoader(ac.getEnvironment());
        loader.addConfigToEnv();
    }

}

PropertiesLoader 从配置中加载属性并将其填充到环境中的工作方式如下：

import com.typesafe.config.Config;
import com.typesafe.config.ConfigFactory;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.MutablePropertySources;

class PropertiesLoader {

    private ConfigurableEnvironment env;

    public PropertiesLoader(ConfigurableEnvironment env) {
        this.env = env;
    }

    public void addConfigToEnv() {
        MutablePropertySources sources = env.getPropertySources();

        Config finalConfig = ConfigFactory.load().resolve();
        // you can also do other stuff like: ConfigFactory.parseFile(), use Config.withFallback to merge configs, etc.
        TypesafeConfigPropertySource source = new TypesafeConfigPropertySource("typeSafe", finalConfig);

        sources.addFirst(source);
    }

}

我们还需要 TypesafeConfigPropertySource 适用于类型安全配置：

import com.typesafe.config.Config;
import org.springframework.core.env.PropertySource;

public class TypesafeConfigPropertySource extends PropertySource<Config> {

    public TypesafeConfigPropertySource(String name, Config source) {
        super(name, source);
    }

    @Override
    public Object getProperty(String path) {
        if (path.contains("["))
            return null;
        if (path.contains(":"))
            return null;
        if (source.hasPath(path)) {
            return source.getAnyRef(path);
        }
        return null;
    }

}

Spring 类型安全配置支持的环境

Spring Environment backed by Typesafe Config

java

spring

spring-mvc

typesafe-config

hocon