我通过使用getResourceAsStream
和maven-assembly-plugin添加了<Class-Path>
从罐子中读取属性文件。起初它起作用。但是,当我添加Maven依赖项Apache POI时,结果变为null
。看来类路径无效。
Java主类
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
public class Main {
public static void main(String[] args) throws IOException {
Properties properties = new Properties();
InputStream in = Main.class.getClassLoader().getResourceAsStream("config/application.properties");
properties.load(in);
System.out.println(properties.getProperty("application.ip"));
}
}
和pom.xml
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<artifactId> maven-assembly-plugin </artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>Main</mainClass>
</manifest>
<manifestEntries>
<Class-Path>.</Class-Path>
</manifestEntries>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
<dependencies>
<!-- if add this dependency,I will get null in Main when getResourceAsStream("config/application.properties")-->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>4.1.0</version>
</dependency>
</dependencies>
mvn打包后,目标目录结构为:
target
| poi-demo-1.0-SNAPSHOT-jar-with-dependencies.jar
| poi-demo-1.0-SNAPSHOT.jar
└───config
└───application.properties
application.properties是
application.ip=127.0.0.1
application.port=80
没有poi依赖性,我得到以下结果:
$ java -jar poi-demo-1.0-SNAPSHOT-jar-with-dependencies.jar
127.0.0.1
添加poi依赖项时,我得到了空值:
$ java -jar poi-demo-1.0-SNAPSHOT-jar-with-dependencies.jar
Exception in thread "main" java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Unknown Source)
at java.util.Properties.load0(Unknown Source)
at java.util.Properties.load(Unknown Source)
at Main.main(Main.java:16)