【轉】maven項目引入spring boot依賴之後filter不生效的問題

創建一個maven項目，項目結構如下：

其中，pom.xml的內容如下：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
 
	<groupId>com.pp.test</groupId>
	<artifactId>properties-test</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>
 
	<name>properties-test</name>
	<url>http://maven.apache.org</url>
 
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.9.RELEASE</version>
	</parent>
 
	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<maven.compiler.source>1.8</maven.compiler.source>
		<maven.compiler.target>1.8</maven.compiler.target>
		<java.version>1.8</java.version>
	</properties>
 
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
	</dependencies>
 
	<build>
		<filters>
			<filter>src/main/profiles/profile-${profiles.active}.properties</filter>
		</filters>
		<resources>
			<resource>
				<filtering>true</filtering>
				<directory>src/main/resources</directory>
			</resource>
		</resources>
	</build>
 
 
	<profiles>
		<profile>
			<id>dev</id>
			<properties>
				<profiles.active>dev</profiles.active>
			</properties>
			<activation>
				<activeByDefault>true</activeByDefault>
			</activation>
		</profile>
		<profile>
			<id>test</id>
			<properties>
				<profiles.active>test</profiles.active>
			</properties>
		</profile>
		<profile>
			<id>prod</id>
			<properties>
				<profiles.active>prod</profiles.active>
			</properties>
		</profile>
	</profiles>
</project>

application.properties 文件內容：

jdbc.driverClassName=${jdbc.driverClassName}
jdbc.url=${jdbc.url}
jdbc.username=${jdbc.username}
jdbc.password=${jdbc.password}

profile-dev.properties 文件內容：

jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql:///db_users
jdbc.username=root
jdbc.password=root

啓動應用，報錯了，錯誤如下：

Caused by: java.lang.IllegalArgumentException: Circular placeholder reference 'jdbc.url' in property definitions
	at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:141) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:162) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:236) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.AbstractPropertyResolver.resolveNestedPlaceholders(AbstractPropertyResolver.java:227) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:84) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:61) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.AbstractEnvironment.getProperty(AbstractEnvironment.java:527) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$1.getProperty(PropertySourcesPlaceholderConfigurer.java:132) ~[spring-context-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$1.getProperty(PropertySourcesPlaceholderConfigurer.java:129) ~[spring-context-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:81) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.PropertySourcesPropertyResolver.getPropertyAsRawString(PropertySourcesPropertyResolver.java:71) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.AbstractPropertyResolver$1.resolvePlaceholder(AbstractPropertyResolver.java:239) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:147) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:236) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$2.resolveStringValue(PropertySourcesPlaceholderConfigurer.java:172) ~[spring-context-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:831) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1086) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
	... 17 common frames omitted

報這個錯誤的原因是，maven的filtering沒有起作用，沒有把佔位符給替換掉。（大家可以執行mvn clean package，看看打包後的jar裏面的application.properties文件，是否有替換佔位符）

filtering無效的原因是，pom.xml繼承了spring boot的依賴

<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>1.5.9.RELEASE</version>
</parent>

點開這個依賴的pom.xml，我們發現

spring boot把默認的佔位符號${}改成了@

找到原因了，那怎麼解決就很簡單了。

方法一：
在pom.xml裏面添加如下內容

<properties>
	<resource.delimiter>${}</resource.delimiter>
</properties>

方法二：
application.properties裏面不用${}，改成@

jdbc.driverClassName=@jdbc.driverClassName@
jdbc.url=@jdbc.url@
jdbc.username=@jdbc.username@
jdbc.password=@jdbc.password@

方法三：
pom.xml不繼承spring-boot-starter-parent，dependency裏面配置全部的依賴和版本號（繼承了之後，很多依賴不用寫version）

方法四：
把

<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>1.5.9.RELEASE</version>
</parent>

改成

<dependencyManagement>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
			<version>1.5.9.RELEASE</version>
			<type>pom</type>
			<scope>import</scope>
		</dependency>
	</dependencies>
</dependencyManagement>