如何使用@ConfigurationProperties進行列表值或數組值映射？

Question

我有一個項目，我想配置字符串鍵「組」 字符串鍵「命令」的字符串數組。也就是說，我想 能夠表達的東西像config.yml以下，並通過 消費@ConfigurationProperties（PREFIX =「config.base」）：

--- 
config: 
    base: 
    "bin group": 
    - "Directory Listing": ["/bin/ls", "-la"] 
    - "Server Date/Time": ["/bin/date", "-u"] 
    "usr/bin group": 
    - "Find .txt Files": ["/usr/bin/find", ".", "-name", "*.txt"] 
    "usr/local/bin group": 
    - "Tree Listing": ["/usr/local/bin/tree"] 

理想的情況下，我d想@ConfigurationProperties對象是一個LinkedHashMap<String, LinkedHashMap<String, String[]>>

但我不知道如何做到這一點。或者任何合理的接近。 我已經得到最接近的是這樣的：

package us.w7tek.bug; 

import org.springframework.beans.factory.annotation.Autowired; 
import org.springframework.boot.SpringApplication; 
import org.springframework.boot.autoconfigure.SpringBootApplication; 
import org.springframework.boot.context.properties.ConfigurationProperties; 
import org.springframework.boot.context.properties.EnableConfigurationProperties; 
import org.springframework.context.annotation.Bean; 
import org.springframework.stereotype.Controller; 

import javax.annotation.PostConstruct; 
import java.util.LinkedHashMap; 

@EnableConfigurationProperties 
@SpringBootApplication 
public class MainApplication { 

    public static void main(String[] args) { 
     SpringApplication.run(MainApplication.class, args); 
    } 

    @ConfigurationProperties("someConfig") 
    @Bean 
    public ExternalizedConfig externalizedConfig() { return new ExternalizedConfig(); } 

    public static class ExternalizedConfig extends LinkedHashMap<String, String[]> { 
     // oops, @ConfigurationProperties ends up putting LinkedHashMap<String, String> in the values of the top-level mapping, 
     // and that second-level LinkedHashMap has keys that could have come from Integer#toString 
    } 

    @Controller 
    public static class ControllerThatConsumesConfig { 
     private static final String A_KEY_THAT_COULDNT_BE_A_PROPERTY_NAME = "this == config cannot be expressed as a bean with properties, because the keys cannot be made into Java language identifiers for bean property setters and getters"; 

     @Autowired 
     ExternalizedConfig config; 

     @PostConstruct 
     void init() { 
      String[] strings = config.get(A_KEY_THAT_COULDNT_BE_A_PROPERTY_NAME); // ClassCastException occurs here 

      // doesn't have to occur in @PostConstruct, that was just a convenient place for my demo. 
     } 
    } 
} 

用下面的例子application.yml項目：

--- 
someConfig: 
    "this is a key": ["this", "value", "is", "not", "an", "String[]"] 
    "this is another key": ["it", "is", "deserialized", "as", "LinkedHashMap", "having", "keys", "like", "\"0\"", "and", "\"1\"", "etc."] 
    "this == config cannot be expressed as a bean with properties, because the keys cannot be made into Java language identifiers for bean property setters and getters": ["thereby", "subverting", "Java's", "static", "typing", "and", "resulting", "in", "ClassCastException", "at", "runtime"] 

正如評論指出，該代碼爆炸當彈簧引導@ConfigurationProperties粘結劑創建一個LinkedHashMap<String, LinkedHashMap<String, LinkedHashMap<String, String>>>類型的對象，並將其放在config字段中。當然，只要有任何方法根據其靜態聲明類型訪問config，就會發生ClassCastException。我不確定是否相信這是一個使用@ConfigurationProperties所使用的屬性聯編程序代碼的錯誤，或者只是我的重大誤解。我認爲上面的代碼是展示問題的最簡單的事情。也可在https://github.com/w7tek/demo-configproperties-bug.git找到，以防有人想編譯並運行以查看堆棧跟蹤。

有沒有人有收集@ConfigurationProperties的任何例子？通過簡單地將聲明的類型與Spring已經反序列化的實際類型進行匹配，我可以從中找到前進的方向，但這最終導致使用起來不方便。如果可能的話，我真的很想獲得這個配置的最內層的值，如列表<>或數組類型，但我不知道如何。

Answer 1

這裏是你需要的東西：

不使用選項卡，使用2個空間，每個內部元件。

config: 
    base: 
    "bin group": 
     "Directory Listing": ["/bin/ls", "-la"] 
     "Server Date/Time": ["/bin/date", "-u"] 
    "usr/bin group": 
     "Find txt Files": ["/usr/bin/find", ".", "-name", "*.txt"] 
    "usr/local/bin group": 
     "Tree Listing": ["/usr/local/bin/tree"] 

，這裏是配置類： 「」

@Configuration 
@ConfigurationProperties(prefix = "config") 
public class Conf_Test { 

    private LinkedHashMap<String, LinkedHashMap<String, List<String>>> base; 

    public LinkedHashMap<String, LinkedHashMap<String, List<String>>> getBase() { 
    return base; 
    } 

    public void setBase(LinkedHashMap<String, LinkedHashMap<String, List<String>>> base) { 
    this.base = base; 
    } 

} 

Apperantly，你不能使用在地圖鍵裏面，它只是剪掉了鍵，所以我刪除了「Find .txt Files」鍵中的那個鍵。此外，spring-boot不支持映射內部的自動格式化數組，因此String []現在不可能，但列表正在工作。