基于Java实现本地APK文件搜索与HTTP下载服务

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class ApkFileFinder {

    private static final String APK_EXTENSION = ".apk";

    /**
     * 查找指定目录下最新的APK文件
     * @param searchDir 搜索目录
     * @return 最新APK文件的Path，未找到时返回null
     * @throws IOException 文件操作异常
     */
    public static Path findLatestApk(String searchDir) throws IOException {
        try (Stream<Path> walk = Files.walk(Paths.get(searchDir))) {
            List<Path> apkFiles = walk
                .filter(Files::isRegularFile)
                .filter(p -> p.getFileName().toString().toLowerCase().endsWith(APK_EXTENSION))
                .collect(Collectors.toList());

            if (apkFiles.isEmpty()) {
                return null;
            }

            return apkFiles.stream()
                .max(Comparator.comparingLong(p -> {
                    try {
                        return Files.getLastModifiedTime(p).toMillis();
                    } catch (IOException e) {
                        return 0;
                    }
                }))
                .orElse(null);
        }
    }
}

import java.io.IOException;
import java.net.URLEncoder;
import java.nio.file.Files;
import java.nio.file.Path;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/downloadLatestApk")
public class ApkDownloadServlet extends HttpServlet {

    private static final String APK_SEARCH_DIR = "C:/apps/";
    private static final String DEFAULT_CHARSET = "UTF-8";

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try {
            // 设置响应编码
            resp.setCharacterEncoding(DEFAULT_CHARSET);
            
            // 查找最新APK
            Path latestApk = ApkFileFinder.findLatestApk(APK_SEARCH_DIR);
            if (latestApk == null) {
                resp.sendError(HttpServletResponse.SC_NOT_FOUND, "未找到APK文件");
                return;
            }
            
            // 设置响应头
            String fileName = generateDownloadFileName(latestApk);
            resp.setContentType("application/vnd.android.package-archive");
            resp.setHeader("Content-Disposition", "attachment; filename="" + URLEncoder.encode(fileName, DEFAULT_CHARSET) + """);
            resp.setHeader("Content-Length", String.valueOf(Files.size(latestApk)));
            
            // 输出文件内容
            Files.copy(latestApk, resp.getOutputStream());
        } catch (Exception e) {
            resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, "下载过程中发生错误: " + e.getMessage());
        }
    }

    private String generateDownloadFileName(Path sourcePath) {
        String baseName = sourcePath.getFileName().toString();
        int extIndex = baseName.lastIndexOf('.');
        String nameWithoutExt = extIndex > 0 ? baseName.substring(0, extIndex) : baseName;
        
        String timestamp = LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyyMMdd_HHmmss"));
        return nameWithoutExt + "_" + timestamp + ".apk";
    }
}

<dependencies>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>4.0.1</version>
        <scope>provided</scope>
    </dependency>
</dependencies>