作為 Spring Boot 項(xiàng)目的一部分，我試圖在創(chuàng)建 Spring ApplicationContext 之前讀取 application.properties，如下所示，主類package com.example.demo;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.context.ApplicationContext;@SpringBootApplicationpublic class DemoApplication {    public static void main(String[] args) {        ConfigurationClass con = new ConfigurationClass();        con.readProperties();        ApplicationContext c = SpringApplication.run(DemoApplication.class, args);    }}配置類，package com.example.demo;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.PropertySource;import org.springframework.core.env.Environment;@Configuration@PropertySource("classpath:application.properties")public class ConfigurationClass {    private String value1;    private String value2;    @Autowired    private Environment env;    public void readProperties() {        value1 = env.getProperty("app.value1");        value2 = env.getProperty("app.value2");    }    public String getValue1() {        return value1;    }    public String getValue2() {        return value2;    }}我想從 application.properties 中獲取一些基本值并進(jìn)行一些配置。這段代碼發(fā)生的事情是它拋出一個nullpointerexceptionsince envis null during value1 = env.getProperty("app.value1");。我在這里做錯了什么？在創(chuàng)建 springapplication 上下文之前的這個時(shí)間點(diǎn)，我如何讀取 application.properties 中的值？任何幫助，將不勝感激！