Java文件处理：form-data 文件上传和下载

pom.xml

		<dependency>
			<groupId>org.apache.poi</groupId>
			<artifactId>poi</artifactId>
			<version>3.17</version>
		</dependency>
		<dependency>
			<groupId>org.apache.poi</groupId>
			<artifactId>poi-ooxml</artifactId>
			<version>3.17</version>
		</dependency>

服务端代码

以下代码只代表实现方法、具体使用需要根据框架进行修改

import org.apache.commons.lang3.StringUtils;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.usermodel.WorkbookFactory;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;

public class FileServer {

    /**
     * 2003 excel后缀
     */
    private static final String EXCEL_XLS = "xls";

    /**
     * 2007 及以上版本excel后缀
     */
    private static final String EXCEL_XLSX = "xlsx";

    public String uploadFile(HttpServletRequest request) {
        MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
        MultipartFile file = multipartRequest.getFile("file");
        File desFile = new File("E:\\" + file.getOriginalFilename());
        if (!desFile.getParentFile().exists()) {
            desFile.mkdirs();
        }
        try {
            file.transferTo(desFile);
        } catch (IllegalStateException | IOException e) {
            e.printStackTrace();
            return "FAILED";
        }
        return "SUCCESS";
    }

    public String downloadFile(HttpServletResponse response) {
        OutputStream out = null;
        try {
            // 获取输入流
            File file = new File("E:\\123.txt");
            BufferedInputStream in = new BufferedInputStream(new FileInputStream(file));
            // 保持文件名
            String fileName = file.getName();
            // 防止中文名乱码
            fileName = URLEncoder.encode(fileName, "UTF-8");
            // 设置文件下载头
            response.addHeader("Content-Disposition", "attachment;filename=" + fileName);
            // 设置文件ContentType类型
            response.setContentType("multipart/form-data");
            out = new BufferedOutputStream(response.getOutputStream());
            String suffix = StringUtils.substringAfterLast(fileName, ".");
            if ((suffix.equals(EXCEL_XLS) || suffix.equals(EXCEL_XLSX))) {
                Workbook workbook = WorkbookFactory.create(new FileInputStream(file));
                workbook.write(out);
                workbook.close();
            } else {
                byte[] buff = new byte[10 * 1024];
                while (in.read(buff) != -1) {
                    out.write(buff);
                    //清空缓存区中的数据流
                    out.flush();
                }
            }
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InvalidFormatException e) {
            e.printStackTrace();
        } finally {
            try {
                if (out != null) {
                    out.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return "SUCCESS";
    }

}