线程“main”中的异常 java.lang.ExceptionInInitializerError，inStream 参数为 null

Question

我正在尝试通过 eclipse 连接到我的 DBeaver 数据库，但它不起作用。 我正在尝试从资源文件夹中的 application.resources 文件中读取，但是当我尝试连接时，它说我的属性变量是 null。

这就是我的目录看起来像目录的样子

这是完整的堆栈跟踪

Caused by: java.lang.NullPointerException: inStream parameter is null
    at java.base/java.util.Objects.requireNonNull(Objects.java:233)
    at java.base/java.util.Properties.load(Properties.java:407)
    at com.revature.utils.DAOUtility.<clinit>(DAOUtility.java:21)

这是我的代码：

package com.revature.utils;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;


public class DAOUtility {
    private static String CONNECTION_USERNAME;
    private static String CONNECTION_PASSWORD;
    private static String CONNECTION_URL;
    private static Connection connection;
    
    static {
        try {
            InputStream input = ClassLoader.getSystemResourceAsStream("application.properties");
            Properties properties = new Properties();
            properties.load(input);
            
            String SYSTEM_VARIABLE_USERNAME = properties.getProperty("USERNAME_PROPERTY");
            String SYSTEM_VARIABLE_PASSWORD = properties.getProperty("PASSWORD_PROPERTY");
            String SYSTEM_VARIABLE_URL = properties.getProperty("URL_PROPERTY");
            
            CONNECTION_USERNAME = System.getenv(SYSTEM_VARIABLE_USERNAME);
            CONNECTION_PASSWORD = System.getenv(SYSTEM_VARIABLE_PASSWORD);
            CONNECTION_URL = System.getenv(SYSTEM_VARIABLE_URL);
            
            input.close();
        } catch(IOException ex) {
            ex.printStackTrace();
        }
        
    }
    
    public static Connection getConnection() throws SQLException {
        // not necessary if it can be found in classpath
        try {
            Class.forName("org.postgresql.Driver");
        } catch (ClassNotFoundException ex) {
            System.out.println("Could not register driver!");
            ex.printStackTrace();
        }
        
        if (connection == null || connection.isClosed()) {
            System.out.println(CONNECTION_URL);
            //System.out.print(new File("").getAbsolutePath());
            connection = DriverManager.getConnection(CONNECTION_URL, CONNECTION_USERNAME, CONNECTION_PASSWORD);
        }
        
        return connection;
    }
    
    public static void main(String[] args) {
        // try to register our driver: optional
        try {
            // registers a driver to driver manager: class responsible for getting a connection
            Class.forName("org.postgresql.Driver");
        } catch (ClassNotFoundException ex) {
            System.out.println("Could not register driver!");
            ex.printStackTrace();
        }
        
        try {
            Connection connection = DriverManager.getConnection(CONNECTION_URL, CONNECTION_USERNAME, CONNECTION_PASSWORD);
            System.out.println("Connection is valid: " + connection.isValid(5));
        } catch (SQLException ex) {
            System.out.println("Connection attempt failed!");
            ex.printStackTrace();
        }
    }
}

这是我的 pom.xml

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.revature</groupId>
  <artifactId>bank-project</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>bank-project</name>
  <description>Bank Project for RAP</description>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <resources>
      <resource>
        <directory>resources</directory>
        <excludes>
          <exclude>**/*.java</exclude>
        </excludes>
      </resource>
    </resources>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.1</version>
        <configuration>
          <release>16</release>
        </configuration>
      </plugin>
    </plugins>
  </build>
  <!-- create 'dependencies' element -->
    <dependencies>
        
        <!-- Add in any dependencies -->
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.3.0</version>
        </dependency>
    </dependencies>
</project>

我已将资源文件夹从常规文件夹更改为源文件夹并将其移动到我的“src”文件夹中，但我仍然收到 null 错误