当我main()从IntelliJ运行时，我得到了预期的peter,johnson结果，这是标准输出的结果。但是，当我运行mvn clean package并尝试执行时，出现java -jar target/example-1.0.0-SNAPSHOT-jar-with-dependencies.jar以下错误消息。为什么以及如何确保读取.properties文件？
java -jar target/example-1.0.0-SNAPSHOT-jar-with-dependencies.jar
Exception in thread "main" java.io.FileNotFoundException: file:/Users/ismar.slomic/src/ADOP/example/target/example-1.0.0-SNAPSHOT- jar-with-dependencies.jar!/my-example.properties (No such file or directory)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(FileInputStream.java:195)
at java.io.FileInputStream.<init>(FileInputStream.java:138)
at java.io.FileInputStream.<init>(FileInputStream.java:93)
at com.example.MyPropertiesClass.getFullName(MyPropertiesClass.java:18)
at com.example.MyMainClass.main(MyMainClass.java:9)
MyMainClass
package com.example;
import java.io.IOException;
public class MyMainClass {
public static void main(String[] args) throws IOException {
MyPropertiesClass mpc = new MyPropertiesClass();
System.out.println(mpc.getFullName());
}
}
MyPropertiesClass
package com.example;
import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;
public class MyPropertiesClass {
public String getFullName() throws IOException {
Properties properties = new Properties();
ClassLoader cl = this.getClass().getClassLoader();
String filePath = cl.getResource("my-example.properties").getFile();
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(filePath));
properties.load(bis);
String name = properties.getProperty("name");
String lastname = properties.getProperty("lastname");
return name + "," + lastname;
}
}
my-example.properties
name=peter
lastname=johnson
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://maven.apache.org/POM/4.0.0"
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.example</groupId>
<artifactId>example</artifactId>
<version>1.0.0-SNAPSHOT</version>
<name>${project.artifactId}</name>
<description>My Example</description>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>3.0.0</version>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>com.example.MyMainClass</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
如果您的属性文件在jar中，则最好getResourceAsStream代替getResource和使用getFile。
就像是：
ClassLoader cl = this.getClass().getClassLoader();
try (InputStream stream = cl.getResourceAsStream("my-example.properties")) {
properties.load(bis);
}
该方法getResource(String)返回指向jar内文件的URL。在您的情况下，类似：file:/Users/ismar.slomic/src/ADOP/example/target/example-1.0.0-SNAPSHOT-jar-with-dependencies.jar!/my-example.properties。当您调用getFile该URL时，它将返回文件（即jar），而不是指向内部属性文件的指针。
也可以在URL上打开连接并使用返回的JarURLConnection。但是使用会更容易getResourceAsStream。
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