使用maven构建后找不到来自src / main / resources的资源

Question

Hello I'm using a configuration file from src/main/resources in my java application. I'm reading it in my Class like this :

new BufferedReader(new FileReader(new File("src/main/resources/config.txt")));

So now I'm building this with maven using mvn assembly:assembly . Here is the bit for that in my pom.xml :

<plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>2.3</version>
                <configuration>
                    <finalName>TestSuite</finalName>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <mainClass>com.some.package.Test</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>

So when I run my app I get this error :

src\main\resources\config.txt (The system cannot find the path specified)

But when I right click on my assembled jar I can see it inside, anyone knows what I'm doing wrong?

Answer 1

Resources from src/main/resources will be put onto the root of the classpath, so you'll need to get the resource as:

new BufferedReader(new InputStreamReader(getClass().getResourceAsStream("/config.txt")));

You can verify by looking at the JAR/WAR file produced by maven as you'll find config.txt in the root of your archive.

Answer 2

FileReader reads from files on the file system.

Perhaps you intended to use something like this to load a file from the class path

// this will look in src/main/resources before building and myjar.jar! after building.
InputStream is = MyClass.class.getClassloader()
                     .getResourceAsStream("config.txt");

Or you could extract the file from the jar before reading it.

Answer 3

您在src / main / resources中放入的资源将在构建过程中复制到目标/类，可以使用以下方式访问：

...this.getClass().getResourceAsStream("/config.txt");

Answer 4

Once after we build the jar will have the resource files under BOOT-INF/classes or target/classes folder, which is in classpath, use the below method and pass the file under the src/main/resources as method call getAbsolutePath("certs/uat_staging_private.ppk") , even we can place this method in Utility class and the calling Thread instance will be taken to load the ClassLoader to get the resource from class path.

 public String getAbsolutePath(String fileName) throws IOException {
      return Thread.currentThread().getContextClassLoader().getResource(fileName).getFile();
  }

we can add the below tag to tag in pom.xml to include these resource files to build target/classes folder

<resources>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.ppk</include>
            </includes>
        </resource>
</resources>

Answer 5

I think assembly plugin puts the file on class path. The location will be different in in the JAR than you see on disk. Unpack the resulting JAR and look where the file is located there.

Answer 6

You can replace the src/main/resources/ directly by classpath:

So for your example you will replace this line:

new BufferedReader(new FileReader(new File("src/main/resources/config.txt")));

By this line:

new BufferedReader(new FileReader(new File("classpath:config.txt")));