读取资源时出现空结果

Question

这是我的项目结构：

这是我的代码，尝试读取资源文件夹中的文件：

package passgen;

public class Application {

  public static void main(String[] args) {
        System.out.println(Application.class.getResourceAsStream("/configuration.properties"));
        System.out.println(Application.class.getResource("/configuration.properties"));
        System.out.println(Application.class.getClassLoader().getResourceAsStream("/configuration.properties"));
        System.out.println(Application.class.getClassLoader().getResource("/configuration.properties"));
        System.out.println(new Application().getClass().getResourceAsStream("/configuration.properties"));
        System.out.println(new Application().getClass().getResource("/configuration.properties"));
        System.out.println(new Application().getClass().getClassLoader().getResourceAsStream("/configuration.properties"));
        System.out.println(new Application().getClass().getClassLoader().getResource("/configuration.properties"));
        System.out.println(Application.class.getResourceAsStream("configuration.properties"));
        System.out.println(Application.class.getResource("configuration.properties"));
        System.out.println(Application.class.getClassLoader().getResourceAsStream("configuration.properties"));
        System.out.println(Application.class.getClassLoader().getResource("configuration.properties"));
        System.out.println(new Application().getClass().getResourceAsStream("configuration.properties"));
        System.out.println(new Application().getClass().getResource("configuration.properties"));
        System.out.println(new Application().getClass().getClassLoader().getResourceAsStream("configuration.properties"));
        System.out.println(new Application().getClass().getClassLoader().getResource("configuration.properties"));
  }

结果都是空的:

null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null

将“配置属性”替换为“src/主/资源/配置属性”（带斜杠和不带斜杠）没有任何区别。

其他类似的答案告诉您使用.getClass（）.getClassLoader（）。getResource（fileName），但这已经是其中一行了。为什么它们都为空，我如何获得资源？

采购订单：

<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>passgen</groupId>
<artifactId>passgen</artifactId>
<version>1</version>
<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
</properties>
<build>
    <finalName>passgen</finalName>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <targetPath>${project.build.directory}/dist</targetPath>
            <includes>
                <include>**/*<!-- all resources that go to folder, rest will go into the jar --></include>
            </includes>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
            <excludes>
                <exclude>**/*<!-- all resources that go to folder, rest will go into the jar --></exclude>
            </excludes>
        </resource>
    </resources>
    <plugins>
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.7.0</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>2.6</version>
            <configuration>
                <outputDirectory>${project.build.directory}/dist</outputDirectory>
                <archive>
                    <manifest>
                        <!-- <addClasspath>true</addClasspath> -->
                        <mainClass>
                            passgen.Application
                        </mainClass>
                    </manifest>
                </archive>
            </configuration>
        </plugin>
    </plugins>
</build>

Answer 1

找到答案了。出于某种原因，Eclipse在主/java/resources文件夹中放置了一个排除模式“< code>**”。如果其他人有同样的问题:右击项目-

编辑：出于某种原因，Eclipse在您运行Maven时将**的排除模式添加到src/main/资源文件夹-

编辑2：我发现Eclipse在src/main/资源文件夹上的排除模式是正常的（参见这个答案）。排除意味着不是Eclipse处理src/main/Resources文件夹编译，而是Maven（准确地说，是Eclipse的Maven插件，M2Eclipse）。在类路径中找不到这些资源的事实是由于pom.xml中存在的排除：

<resource>
    <directory>src/main/resources</directory>
    <excludes>
        <!-- these resources will be excluded from the classpath; they will not go in to the target/classes folder and will not be packaged into the artifact -->
        <exclude>**/*</exclude>
    </excludes>
</resource>

我删除了它，得到了下面列出的输出。

现在，上述代码的输出如下：

java.io.BufferedInputStream@7852e922
file:/C:/Users/Taiano/eclipse-workspace/sharedProjects/passgen/target/classes/configuration.properties
null
null
java.io.BufferedInputStream@4e25154f
file:/C:/Users/Taiano/eclipse-workspace/sharedProjects/passgen/target/classes/configuration.properties
null
null
null
null
java.io.BufferedInputStream@70dea4e
file:/C:/Users/Taiano/eclipse-workspace/sharedProjects/passgen/target/classes/configuration.properties
null
null
java.io.BufferedInputStream@5c647e05
file:/C:/Users/Taiano/eclipse-workspace/sharedProjects/passgen/target/classes/configuration.properties

如果要从 jar 中排除资源，请在“专家-jar-插件”部分中将其排除。如果要在输出中生成从 jar 中排除的资源，请使用指定目标文件夹的目标复制资源配置 maven-resources 插件（默认情况下，资源被打包到项目中，如果您只是从项目中排除它们，您将无处可去的资源）。

Answer 2

您必须提供类装入器的完整路径，以防您想从项目目录中装入它。

System.out.println(Application.class.getResourceAsStream("/main/resources/configuration.properties"));

希望这有帮助。