更新了解决方案的执行摘要 根据Victor提供的答案，我实现了一个Java类，它列出了类路径中文件夹资源的内容。对我来说最关键的是，当从IDE执行时，从爆炸的uberjar或未爆炸的uberjar（我通常使用maven shade插件创建）中发现类路径资源时，这必须起作用。）类和相关单元测试可用here。
原始问题
当我运行非常简单时，我看到了maven-shade-plugin和类路径资源的奇怪行为 java测试程序，它访问标准maven项目中的目录结构，如下所示：
src/main
Test.java
resources/
resource-directory
spark
junk1
zeppelin
junk2
从IDE或爆炸的maven阴影.jar运行时（请参见下文） 它可以正常工作 ，这意味着它打印出来：。
result of directory contents as classpath resource:[spark, zeppelin]
来源如下：
import org.apache.commons.io.IOUtils;
import java.io.IOException;
import java.io.InputStream;
public class Tester {
public void test(String resourceName) throws IOException {
InputStream in = this.getClass().getClassLoader().getResourceAsStream(resourceName);
System.out.println("input stream: " + in);
Object result = IOUtils.readLines(in);
System.out.println("result of directory contents as classpath resource:" + result);
}
public static void main(String[] args) throws IOException {
new Tester().test("resource-directory");
}
}
现在，如果我在我的项目中运行mvn clean install并运行
在$ {project.dir}目标下的maven shaded .jar，我看到以下异常：
> java -jar target/sample.jar
Exception in thread "main" java.lang.NullPointerException
at java.io.FilterInputStream.read(FilterInputStream.java:133)
at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
at java.io.InputStreamReader.read(InputStreamReader.java:184)
at java.io.BufferedReader.fill(BufferedReader.java:161)
at java.io.BufferedReader.readLine(BufferedReader.java:324)
at java.io.BufferedReader.readLine(BufferedReader.java:389)
at org.apache.commons.io.IOUtils.readLines(IOUtils.java:1030)
at org.apache.commons.io.IOUtils.readLines(IOUtils.java:987)
at org.apache.commons.io.IOUtils.readLines(IOUtils.java:968)
at Tester.test(Tester.java:16)
at Tester.main(Tester.java:24)
使用Exploded .jar
运行> mkdir explode/
> cd explode/
> jar xvf ../sample.jar
......
inflated: META-INF/MANIFEST.MF
created: META-INF/
etc etc.
> ls # look at contents of exploded .jar:
logback.xml META-INF org resource-directory Tester.class
#
# now run class with CLASSPATH="."
(master) /tmp/maven-shade-non-working-example/target/explode > java Tester
input stream: java.io.ByteArrayInputStream@70dea4e
result of directory contents as classpath resource:[spark, zeppelin] # <<<- works !
我在这里有整个项目：https://github.com/buildlackey/maven-shade-non-working-example 但是为了方便起见，这里是pom.xml（下面），我尝试了两个maven shade配置 注意：我不认为IncludeResourceTransformer会有任何用处，因为我的资源正在出现 在.jar文件中的适当级别。
<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/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.foo.core</groupId>
<artifactId>sample</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>sample</name>
<url>http://maven.apache.org</url>
<properties>
<jdk.version>1.8</jdk.version>
<junit.version>4.11</junit.version>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency><!-- commons-io: Easy conversion from stream to string list, etc.-->
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.4</version>
</dependency>
</dependencies>
<build>
<finalName>sample</finalName>
<plugins>
<!-- Set a compiler level -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>${jdk.version}</source>
<target>${jdk.version}</target>
</configuration>
</plugin>
<!-- Maven Shade Plugin -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.3</version>
<executions>
<!-- Run shade goal on package phase -->
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<!-- add Main-Class to manifest file -->
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>Tester</mainClass>
</transformer>
<!-- tried with the stanza below enabled, and also disabled: in both cases, got exceptions from runs -->
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>src/main/resources/</resource>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
无论如何，提前感谢您提供的任何帮助〜 克里斯
更新
在我尝试使用Spring时，这对我来说并不适合（但是如果有人在Spring方法上取得成功，我会感兴趣）。我有一个工作替代方案，我将很快发布。但如果你想评论如何解决这个破碎的春季尝试，我会非常感兴趣。
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import java.io.IOException;
public class Tester {
public void test(String resourceName) throws IOException {
ResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver();
Resource[] resources = resourceResolver.getResources("resource-directory/*");
for (Resource resource : resources) {
System.out.println("resource: " + resource.getDescription());
}
}
public static void main(String[] args) throws IOException {
new Tester().test("resource-directory/*");
}
}
答案 0 :(得分：2)
问题是getResourceAsStream只能从jar文件中读取文件作为流而不是文件夹。
要从jar文件中读取文件夹内容，您可能需要使用该方法，如此问题的接受答案中所述：
答案 1 :(得分：0)
为了补充我的好朋友Victor的答案，这是一个完整的代码解决方案。下面。完整项目可用here
import java.io.File;
import java.io.IOException;
import java.util.*;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* List entries of a subfolder of an entry in the class path, which may consist of file system folders and .jars.
*/
public class ClassPathResourceFolderLister {
private static final Logger LOGGER = LoggerFactory.getLogger(ClassPathResourceFolderLister.class);
/**
* For each entry in the classpath, verify that (a) "folder" exists, and (b) "folder" has child content, and if
* these conditions hold, return the child entries (be they files, or folders). If neither (a) nor (b) are true for
* a particular class path entry, move on to the next entry and try again.
*
* @param folder the folder to match within the class path entry
*
* @return the subfolder items of the first matching class path entry, with a no duplicates guarantee
*/
public static Collection<String> getFolderListing(final String folder) {
final String classPath = System.getProperty("java.class.path", ".");
final String[] classPathElements = classPath.split(System.getProperty("path.separator"));
List<String> classPathElementsList = new ArrayList<String> ( Arrays.asList(classPathElements));
return getFolderListingForFirstMatchInClassPath(folder, classPathElementsList);
}
private static Collection<String>
getFolderListingForFirstMatchInClassPath(final String folder, List<String> classPathElementsList) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("getFolderListing for " + folder + " with classpath elements " + classPathElementsList);
}
Collection<String> retval = new HashSet<String>();
String cleanedFolder = stripTrailingAndLeadingSlashes(folder);
for (final String element : classPathElementsList) {
System.out.println("class path element:" + element);
retval = getFolderListing(element, cleanedFolder);
if (retval.size() > 0) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("found matching folder in class path list. returning: " + retval);
}
return retval;
}
}
return retval;
}
private static String stripTrailingAndLeadingSlashes(final String folder) {
String stripped = folder;
if (stripped.equals("/")) { // handle degenerate case:
return "";
} else { // handle cases for strings starting or ending with "/", confident that we have at least two characters
if (stripped.endsWith("/")) {
stripped = stripped.substring(0, stripped.length()-1);
}
if (stripped.startsWith("/")) {
stripped = stripped.substring(1, stripped.length());
}
if (stripped.startsWith("/") || stripped.endsWith("/")) {
throw new IllegalArgumentException("too many consecutive slashes in folder specification: " + stripped);
}
}
return stripped;
}
private static Collection<String> getFolderListing( final String element, final String folderName) {
final File file = new File(element);
if (file.isDirectory()) {
return getFolderContentsListingFromSubfolder(file, folderName);
} else {
return getResourcesFromJarFile(file, folderName);
}
}
private static Collection<String> getResourcesFromJarFile(final File file, final String folderName) {
final String leadingPathOfZipEntry = folderName + "/";
final HashSet<String> retval = new HashSet<String>();
ZipFile zf = null;
try {
zf = new ZipFile(file);
final Enumeration e = zf.entries();
while (e.hasMoreElements()) {
final ZipEntry ze = (ZipEntry) e.nextElement();
final String fileName = ze.getName();
if (LOGGER.isTraceEnabled()) {
LOGGER.trace("zip entry fileName:" + fileName);
}
if (fileName.startsWith(leadingPathOfZipEntry)) {
final String justLeafPartOfEntry = fileName.replaceFirst(leadingPathOfZipEntry,"");
final String initSegmentOfPath = justLeafPartOfEntry.replaceFirst("/.*", "");
if (initSegmentOfPath.length() > 0) {
LOGGER.trace(initSegmentOfPath);
retval.add(initSegmentOfPath);
}
}
}
} catch (Exception e) {
throw new RuntimeException("getResourcesFromJarFile failed. file=" + file + " folder=" + folderName, e);
} finally {
if (zf != null) {
try {
zf.close();
} catch (IOException e) {
LOGGER.error("getResourcesFromJarFile close failed. file=" + file + " folder=" + folderName, e);
}
}
}
return retval;
}
private static Collection<String> getFolderContentsListingFromSubfolder(final File directory, String folderName) {
final HashSet<String> retval = new HashSet<String>();
try {
final String fullPath = directory.getCanonicalPath() + "/" + folderName;
final File subFolder = new File(fullPath);
System.out.println("fullPath:" + fullPath);
if (subFolder.isDirectory()) {
final File[] fileList = subFolder.listFiles();
for (final File file : fileList) {
retval .add(file.getName());
}
}
} catch (final IOException e) {
throw new Error(e);
}
return retval;
}
}