Spring Boot 应用中安全获取资源文件：解决JAR打包后的兼容性问题

String Key = new String(Files.readAllBytes(Paths.get(ClassLoader.getSystemResource("key/private.pem").toURI())));

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.util.FileCopyUtils;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Objects;

public class ResourceLoaderUtil {

    private static final Logger log = LoggerFactory.getLogger(ResourceLoaderUtil.class);

    /**
     * 从类路径加载资源文件内容。
     * 该方法适用于Spring Boot应用打包成JAR后，依然能够正确读取resources目录下的文件。
     *
     * @param resourcePath 资源在类路径下的相对路径，例如 "key/private.pem" 或 "config/application.yml"。
     * @return 资源文件的内容字符串，如果加载失败则返回null。
     * @throws NullPointerException 如果resourcePath为null。
     */
    public static String getResourceFileContent(String resourcePath) {
        Objects.requireNonNull(resourcePath, "Resource path cannot be null.");

        // 创建ClassPathResource实例，它会自动查找类路径下的资源
        ClassPathResource resource = new ClassPathResource(resourcePath);
        try {
            // 使用FileCopyUtils将资源输入流的内容复制到字节数组
            // FileCopyUtils.copyToByteArray 会自动关闭输入流
            byte[] bytes = FileCopyUtils.copyToByteArray(resource.getInputStream());
            // 将字节数组转换为字符串，推荐指定字符集以避免乱码
            return new String(bytes, StandardCharsets.UTF_8);
        } catch (IOException ex) {
            // 记录错误日志，包含资源路径和异常信息
            log.error("Failed to load resource file: {}", resourcePath, ex);
            return null; // 或者抛出自定义异常
        }
    }
}

import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

public class KeyLoader {

    private PublicKey getPublicKey() throws NoSuchAlgorithmException, InvalidKeySpecException {
        // 使用ResourceLoaderUtil获取公钥文件内容
        String keyContent = ResourceLoaderUtil.getResourceFileContent("key/public.pem");
        if (keyContent == null) {
            throw new RuntimeException("Failed to load public key resource.");
        }

        String key = keyContent.replaceAll("\n", "")
                .replace("-----BEGIN PUBLIC KEY-----", "")
                .replace("-----END PUBLIC KEY-----", "");

        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.getDecoder().decode(key));
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePublic(keySpec);
    }

    private PrivateKey getPrivateKey() throws NoSuchAlgorithmException, InvalidKeySpecException {
        // 使用ResourceLoaderUtil获取私钥文件内容
        String keyContent = ResourceLoaderUtil.getResourceFileContent("key/private.pem");
        if (keyContent == null) {
            throw new RuntimeException("Failed to load private key resource.");
        }

        String key = keyContent.replaceAll("\n", "")
                .replace("-----BEGIN PRIVATE KEY-----", "")
                .replace("-----END PRIVATE KEY-----", "");

        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(Base64.getDecoder().decode(key));
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePrivate(keySpec);
    }

    public static void main(String[] args) {
        KeyLoader loader = new KeyLoader();
        try {
            PublicKey publicKey = loader.getPublicKey();
            PrivateKey privateKey = loader.getPrivateKey();
            System.out.println("Public Key loaded: " + (publicKey != null));
            System.out.println("Private Key loaded: " + (privateKey != null));
            // 进一步使用publicKey和privateKey
        } catch (Exception e) {
            System.err.println("Error loading keys: " + e.getMessage());
            e.printStackTrace();
        }
    }
}