Question

我正在寻找一种说法：

val c: Config = ConfigFactory.parseString("a=fox,b=dog")
val s: String = """This is a "quick" brown ${a}.\nThat is a lazy, lazy ${b}."""
println(c.resolveString(s))

// Should print:
// > This is a "quick" brown fox.
// > That is a lazy lazy dog.

我的两个想法：

只需找到带有正则表达式的占位符，然后逐个替换配置
将s转换为具有单一值的配置并使用resolveWith - 但似乎引用可能非常棘手

也许有一种更简单的方法？

Answer 1

天真的解决方案：

class Resolver(vars: Config) {
  private lazy val placeholderRegex = "(?<=\\$\\{).*?(?=\\})".r

  def resolveString(s: String): String = {
    placeholderRegex.findAllIn(s).foldLeft(s) { (str, v) =>
      if (vars.hasPath(v)) str.replaceAll("\\Q${" + v + "}\\E", vars.getString(v)) else str
    }
  }

如果字符串不是很大并且没有疯狂数量的不同占位符，那应该没问题。

Answer 2

我有类似的情况，我之前会自动推送弹性搜索索引定义我启动了使用这些索引定义的作业。

在我的例子中，包含变量引用的字符串是 JSON索引/模板定义，它也来自typesafe配置。（参见下面的es.template_or_index.json。）

我使用我在上面写的实用程序方法解析这些引用 apache.commons StrSubstitutor。

（参见：下面的VariableReferenceResolver.resolveReferences（字符串模板））

以下是我的配置示例。请注意该属性＆＃39; es.animal＆＃39;被注入到索引/模板json中。这不能通过类型安全配置库的开箱即用功能来完成（但我想这会是他们添加的一个很棒的功能！）

 es {
      // user and password credentials should not be checked in to git. deployer is expected to
      // set these parameters into the their environment in whatever way is convenient -- .bashrc or whatever.
      user = dummy
      user = ${?ES_USER}
      password = dummy.passwd
      password = ${?ES_PASSWORD}
      hostPort = "localhost:9200"
      hostPort = ${?ES_HOST_PORT}
      protocol = http
      protocol = ${?ES_PROTOCOL}

      animal = horse            // This gets injected into the configuration property es.template_or_index.json


      // Note: for template json there is a second round of interpolation performed so the json can reference any defined
      // property of this configuration file (or anything it includes)
      template_or_index {
        name = test_template
        json = """
      {
          "template": "${es.animal}_sql-*",
          "settings": {
            "number_of_shards": 50,
            "number_of_replicas": 2
          },
          "mappings": {
                 "test_results" : {
                     "date_detection": false,
                     "properties" : {
                         "timestamp" : { "type" : "date"},
                         "yyyymmdd" : { "type" : "string", "index" : "not_analyzed"}
                     }
                 }
          }
        }
        """
      }
 }



package com.foo

import com.typesafe.config.Config;
import org.apache.commons.lang.text.StrLookup;
import org.apache.commons.lang.text.StrSubstitutor;

public class VariableReferenceResolver {
    final StrSubstitutor substitutor;

    static class ConfigStrLookup extends StrLookup {
          private final Config config;

          ConfigStrLookup(Config config) {
              this.config = config;
          }

          public String lookup(String key) {
              return config.getString(key);
          }
      }

    public VariableReferenceResolver (Config config) {
        substitutor=new StrSubstitutor(new ConfigStrLookup(config));

    }

    public String resolveReferences(String template) {
        return substitutor.replace(template);
    }
}


public class OtherClass { 
    private static void getIndexConfiguration(String path) throws IOException {
        System.setProperty("config.file", path);
        Config config = ConfigFactory.load();
        String user =  config.getString("es.user");
        String password =  config.getString("es.password");
        String protocol =  config.getString("es.protocol");
        String hostPort =  config.getString("es.hostPort");
        String indexOrTemplateJson = config.getString("es.template_or_index.json");
        String indexOrTemplateName = config.getString("es.template_or_index.name");
        VariableReferenceResolver resolver = new VariableReferenceResolver(config);
        String resolvedIndexOrTemplateJson = resolver.resolveReferences(indexOrTemplateJson);

        File jsonFile = File.createTempFile("index-or-template-json", indexOrTemplateName);
        Files.write(Paths.get(jsonFile.getAbsolutePath()), resolvedIndexOrTemplateJson.getBytes());

        curlIndexOrTemplateCreateCommand =
                String.format(
                        "curl  -XPUT  -k -u %s:%s %s://%s/_template/%s -d @%s",
                        user, password, protocol, hostPort, indexOrTemplateName,  jsonFile.getAbsolutePath());
    }


            ....
}

使用typesafe配置解析独立的字符串/文件

2 个答案: