file取り扱い

import com.google.cloud.functions.HttpFunction;
import com.google.cloud.functions.HttpRequest;
import com.google.cloud.functions.HttpResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.fileupload.FileUploadException;

import java.io.*;
import java.util.List;

public class FileUploadFunction implements HttpFunction {

    @Override
    public void service(HttpRequest request, HttpResponse response) throws Exception {
        if (!ServletFileUpload.isMultipartContent(new HttpRequestWrapper(request))) {
            response.setStatusCode(400);
            response.getWriter().write("Content-Type is not multipart/form-data");
            return;
        }

        DiskFileItemFactory factory = new DiskFileItemFactory();
        ServletFileUpload upload = new ServletFileUpload(factory);

        List<FileItem> items;
        try {
            items = upload.parseRequest(new HttpRequestWrapper(request));
        } catch (FileUploadException e) {
            response.setStatusCode(500);
            response.getWriter().write("Failed to parse multipart request");
            return;
        }

        for (FileItem item : items) {
            if (!item.isFormField() && "file".equals(item.getFieldName())) {
                String fileName = item.getName();
                byte[] fileBytes = item.get();

                // ByteArrayInputStream を使って再利用可能に
                ByteArrayInputStream reusableStream = new ByteArrayInputStream(fileBytes);

                // 内容を読み込んで表示（例）
                try (BufferedReader reader = new BufferedReader(new InputStreamReader(reusableStream))) {
                    String line;
                    while ((line = reader.readLine()) != null) {
                        System.out.println("Line: " + line);
                    }
                }

                response.getWriter().write("File received: " + fileName + "\n");
                return;
            }
        }

        response.setStatusCode(400);
        response.getWriter().write("No file part found");
    }
}