springboot application.yml Cannot invoke “Object.toString()“ because “key“ is null

问题描述

• 使用了application.yml
• 启动的时候报错： Cannot invoke “Object.toString()” because “key” is null
• YamlProcessor报错

java.lang.NullPointerException: Cannot invoke "Object.toString()" because "key" is null
	at org.springframework.beans.factory.config.YamlProcessor.lambda$asMap$0(YamlProcessor.java:248)
	at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:721)
	at org.springframework.beans.factory.config.YamlProcessor.asMap(YamlProcessor.java:239)
	at org.springframework.beans.factory.config.YamlProcessor.lambda$asMap$0(YamlProcessor.java:241)
	at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:721)
	at org.springframework.beans.factory.config.YamlProcessor.asMap(YamlProcessor.java:239)
	at org.springframework.beans.factory.config.YamlProcessor.lambda$asMap$0(YamlProcessor.java:241)
	at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:721)
	at org.springframework.beans.factory.config.YamlProcessor.asMap(YamlProcessor.java:239)
	at org.springframework.beans.factory.config.YamlProcessor.process(YamlProcessor.java:200)
	at org.springframework.beans.factory.config.YamlProcessor.process(YamlProcessor.java:166)
	at org.springframework.boot.env.OriginTrackedYamlLoader.load(OriginTrackedYamlLoader.java:84)
	at org.springframework.boot.env.YamlPropertySourceLoader.load(YamlPropertySourceLoader.java:50)
	at org.springframework.boot.context.config.StandardConfigDataLoader.load(StandardConfigDataLoader.java:54)
	at org.springframework.boot.context.config.StandardConfigDataLoader.load(StandardConfigDataLoader.java:36)
	at org.springframework.boot.context.config.ConfigDataLoaders.load(ConfigDataLoaders.java:96)
	at org.springframework.boot.context.config.ConfigDataImporter.load(ConfigDataImporter.java:132)
	at org.springframework.boot.context.config.ConfigDataImporter.resolveAndLoad(ConfigDataImporter.java:87)
	at org.springframework.boot.context.config.ConfigDataEnvironmentContributors.withProcessedImports(ConfigDataEnvironmentContributors.java:115)
	at org.springframework.boot.context.config.ConfigDataEnvironment.processInitial(ConfigDataEnvironment.java:242)
	at org.springframework.boot.context.config.ConfigDataEnvironment.processAndApply(ConfigDataEnvironment.java:229)
	at org.springframework.boot.context.config.ConfigDataEnvironmentPostProcessor.postProcessEnvironment(ConfigDataEnvironmentPostProcessor.java:96)
	at org.springframework.boot.context.config.ConfigDataEnvironmentPostProcessor.postProcessEnvironment(ConfigDataEnvironmentPostProcessor.java:89)
	at org.springframework.boot.env.EnvironmentPostProcessorApplicationListener.onApplicationEnvironmentPreparedEvent(EnvironmentPostProcessorApplicationListener.java:109)
	at org.springframework.boot.env.EnvironmentPostProcessorApplicationListener.onApplicationEvent(EnvironmentPostProcessorApplicationListener.java:94)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:131)
	at org.springframework.boot.context.event.EventPublishingRunListener.multicastInitialEvent(EventPublishingRunListener.java:136)
	at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:81)
	at org.springframework.boot.SpringApplicationRunListeners.lambda$environmentPrepared$2(SpringApplicationRunListeners.java:64)
	at java.base/java.lang.Iterable.forEach(Iterable.java:75)
	at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:118)
	at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:112)
	at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:63)
	at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:356)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:307)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1295)
	at com.lxkplus.mybatisMaker.MybatisMakerApplication.main(MybatisMakerApplication.java:14)

原因描述：

YamlProcessor会把Map转化为Map<String, Object>
而数字、布尔值和null会序列化失败。

YAML 中的保留字是指在 YAML 语法中有特殊意义的单词，比如 on、true、false 和 null 等。如果你想在 YAML 中使用这些保留字作为映射的键或值，你需要用引号括起来，这样 YAML 解析器会将它们当作普通的字符串处理。

然后再加一条：大写NULL也是保留字

而NULL转化为String
解决方案：NULL填加双引号“NULL”即可。