使用 Jersey 伺服器實現上傳，使用 HTTP 請求實現下載

引入依賴

在 pom.xml 中新增 Jersey 相關依賴

<dependency>
  <groupId>com.sun.jersey</groupId>
  <artifactId>jersey-client</artifactId>
  <version>1.18.1</version>
</dependency>

建立工具類

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientHandlerException;
import com.sun.jersey.api.client.UniformInterfaceException;
import com.sun.jersey.api.client.WebResource;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.UUID;

public class FileUtils {

  // 加密/解密檔案的金鑰
  public static final int CRYPTO_SECRET_KEY = 0x99;

  public static int FILE_DATA = 0;

  /**
   * 加密/解密 檔案
   * @param srcFile 原檔案
   * @param encFile 加密/解密後的檔案
   * @throws Exception
   */
  public static void cryptoFile(File srcFile,File encFile) throws Exception {

    InputStream inputStream = new FileInputStream(srcFile);
    OutputStream outputStream = new FileOutputStream(encFile);
    while ((FILE_DATA = inputStream.read()) > -1) {
      outputStream.write(FILE_DATA ^ CRYPTO_SECRET_KEY);
    }
    inputStream.close();
    outputStream.flush();
    outputStream.close();
  }

  /**
   * MultipartFile 生成臨時檔案
   * @param multipartFile
   * @param tempFilePath 臨時檔案路徑
   * @return File 臨時檔案
   */
  public static File multipartFileToFile(MultipartFile multipartFile,String tempFilePath) {

    File file = new File(tempFilePath);
    // 獲取檔案原名
    String originalFilename = multipartFile.getOriginalFilename();
    // 獲取檔案字尾
    String suffix = originalFilename.substring(originalFilename.lastIndexOf("."));
    if (!file.exists()) {
      file.mkdirs();
    }
    // 建立臨時檔案
    File tempFile = new File(tempFilePath + "\\" + UUID.randomUUID().toString().replaceAll("-","") + suffix);
    try {
      if (!tempFile.exists()) {
        // 寫入臨時檔案
        multipartFile.transferTo(tempFile);
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
    return tempFile;
  }

  /**
   * 上傳檔案
   * @param fileServerPath	檔案伺服器地址
   * @param folderPath  存放的資料夾路徑（比如存放在檔案伺服器的 upload 資料夾下，即 ”/upload“）
   * @param uploadFile	需要上傳的檔案
   * @param isCrypto	是否加密
   * @return String	檔案上傳後的全路徑
   */
  public static String uploadByJersey(String fileServerPath,String folderPath,File uploadFile,boolean isCrypto) {

    String suffix = uploadFile.getName().substring(uploadFile.getName().lastIndexOf("."));
    String randomFileName = UUID.randomUUID().toString().replaceAll("-","") + suffix;
    String fullPath = fileServerPath + folderPath + "/" + randomFileName;
    try {
      if (isCrypto) {
        // 建立加密檔案
        File cryptoFile = new File(uploadFile.getPath().substring(0,uploadFile.getPath().lastIndexOf(".")) + "crypto" + uploadFile.getPath().substring(uploadFile.getPath().lastIndexOf(".")));
        // 執行加密
        cryptoFile(uploadFile,cryptoFile);
        // 儲存加密後的檔案
        uploadFile = cryptoFile;
      }
      // 建立 Jersey 伺服器
      Client client = Client.create();
      WebResource wr = client.resource(fullPath);
      // 上傳檔案
      wr.put(String.class,fileToByte(uploadFile));
    } catch (Exception e) {
      e.printStackTrace();
    }
    return fullPath;
  }

  /**
   * 下載檔案
   * @param url  檔案路徑
   * @param filePath 檔案儲存路徑
   * @param fileName	檔名稱（包含檔案字尾）
   * @param isCrypto 是否解密
   * @return File
   */
  public static File downloadByURL(String url,String filePath,String fileName,boolean isCrypto) {

    File file = new File(filePath);
    if (!file.exists()) {
      file.mkdirs();
    }
    FileOutputStream fileOut;
    HttpURLConnection httpURLConnection;
    InputStream inputStream;
    try {
      URL httpUrl = new URL(url);
      httpURLConnection = (HttpURLConnection) httpUrl.openConnection();
      httpURLConnection.setDoInput(true);
      httpURLConnection.setDoOutput(true);
      httpURLConnection.setUseCaches(false);
      httpURLConnection.connect();
      inputStream = httpURLConnection.getInputStream();
      BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
      if (!filePath.endsWith("\\")) {
        filePath += "\\";
      }
      file = new File(filePath + fileName);
      fileOut = new FileOutputStream(file);
      BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(fileOut);
      byte[] bytes = new byte[4096];
      int length = bufferedInputStream.read(bytes);
      //儲存檔案
      while (length != -1) {
        bufferedOutputStream.write(bytes,length);
        length = bufferedInputStream.read(bytes);
      }
      bufferedOutputStream.close();
      bufferedInputStream.close();
      httpURLConnection.disconnect();
    } catch (Exception e) {
      e.printStackTrace();
    }
    if (isCrypto) {
      try {
        // 建立解密檔案
        File cryptoFile = new File(((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest().getServletContext().getRealPath("/") + "\\temp\\" + UUID.randomUUID().toString().replaceAll("-","") + file.getName().substring(file.getName().lastIndexOf(".")));
        // 執行解密
        cryptoFile(file,cryptoFile);
        // 刪除下載的原檔案
        file.delete();
        // 儲存解密後的檔案
        file = cryptoFile;
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
    return file;
  }

  /**
   * 刪除檔案伺服器上的檔案
   * @param url 檔案路徑
   * @return boolean
   */
  public static boolean deleteByJersey(String url) {

    try {
      Client client = new Client();
      WebResource webResource = client.resource(url);
      webResource.delete();
      return true;
    } catch (UniformInterfaceException e) {
      e.printStackTrace();
    } catch (ClientHandlerException e) {
      e.printStackTrace();
    }
    return false;
  }

  /**
   * File轉Bytes
   * @param file
   * @return byte[]
   */
  public static byte[] fileToByte(File file) {

    byte[] buffer = null;
    try {
      FileInputStream fileInputStream = new FileInputStream(file);
      ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
      byte[] bytes = new byte[1024];
      int n;
      while ((n = fileInputStream.read(bytes)) != -1) {
        byteArrayOutputStream.write(bytes,n);
      }
      fileInputStream.close();
      byteArrayOutputStream.close();
      buffer = byteArrayOutputStream.toByteArray();
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    return buffer;
  }
}

測試上傳

/**
 * @param multipartFile 上傳檔案
 * @param isCrypto 是否加密檔案
 * @return
 */
@Test
public String upload(MultipartFile multipartFile,boolean isCrypto) {

  HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
  // 生成臨時檔案
  File tempFile = FileUtil.multipartFileToFile(multipartFile,request.getServletContext().getRealPath("/") + "\\static\\temp");
  // 上傳檔案並返回檔案路徑
  String uploadFilePath = FileUtil.uploadByJersey("http://localhost:8080","/upload",tempFile,isCrypto);
  if (uploadFilePath != null) {
    return "上傳成功";
  }
  else {
    return "上傳失敗";
  }
}

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