SpringBoot でファイルのダウンロードを実現するいくつかの方法
1. ファイルをストリーム形式でメモリに一括読み込みし、レスポンス出力ストリームを通じてフロントエンドに出力します。
@RequestMapping("/download")
public void download(String path, HttpServletResponse response) {
try {
File file = new File(path);
log.info(file.getPath());
String filename = file.getName();
String ext = filename.substring(filename.lastIndexOf(".") + 1).toLowerCase();
log.info("文件后缀名:" + ext);
FileInputStream fileInputStream = new FileInputStream(file);
InputStream fis = new BufferedInputStream(fileInputStream);
byte[] buffer = new byte[fis.available()];
fis.read(buffer);
fis.close();
response.reset();
response.setCharacterEncoding("UTF-8");
response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
response.addHeader("Content-Length", "" + file.length());
OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
response.setContentType("application/octet-stream");
outputStream.write(buffer);
outputStream.flush();
} catch (IOException ex) {
ex.printStackTrace();
}
}
1.1 ファイルをダウンロードする
@RequestMapping("getFile")
@ResponseBody
public void getFile(HttpServletResponse response) throws Exception{
File readFile = new File("/home/ssx/Music/CloudMusic/夜曲-周杰伦.flac");
FileInputStream fileInputStream = new FileInputStream(readFile);
response.setHeader("content-disposition","attachment;filename="+ URLEncoder.encode("夜曲-周杰伦.flac","utf-8"));
ServletOutputStream outputStream = response.getOutputStream();
byte[] bytes = new byte[1024*10];
int read;
do {
read = fileInputStream.read(bytes);
outputStream.write(bytes,0,read);
}while (-1 != read);
IOUtils.closeQuietly(fileInputStream);
IOUtils.closeQuietly(outputStream);
}
2. 入力ストリームのデータを一度にメモリに読み込むのではなく、周期的に応答出力ストリームに書き込み、応答出力ストリームを通じてフロントエンドに出力します。
@RequestMapping("/downloadLocal")
public void downloadLocal(String path, HttpServletResponse response) throws IOException {
InputStream inputStream = new FileInputStream(path);
response.reset();
response.setContentType("application/octet-stream");
String filename = new File(path).getName();
response.addHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(filename, "UTF-8"));
ServletOutputStream outputStream = response.getOutputStream();
byte[] b = new byte[1024];
int len;
while ((len = inputStream.read(b)) > 0) {
outputStream.write(b, 0, len);
}
inputStream.close();
}
3. ネットワーク ファイルをローカルにダウンロードします。
@RequestMapping("/netDownloadLocal")
public void downloadNet(String netAddress, String path) throws IOException {
URL url = new URL(netAddress);
URLConnection conn = url.openConnection();
InputStream inputStream = conn.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream(path);
int bytesum = 0;
int byteread;
byte[] buffer = new byte[1024];
while ((byteread = inputStream.read(buffer)) != -1) {
bytesum += byteread;
System.out.println(bytesum);
fileOutputStream.write(buffer, 0, byteread);
}
fileOutputStream.close();
}
4. ネットワーク ファイルをサーバーから取得した後、サーバーによって処理された後、フロント エンドに応答します。
@RequestMapping("/netDownLoadNet")
public void netDownLoadNet(String netAddress, String filename, boolean isOnLine, HttpServletResponse response) throws Exception {
URL url = new URL(netAddress);
URLConnection conn = url.openConnection();
InputStream inputStream = conn.getInputStream();
response.reset();
response.setContentType(conn.getContentType());
if (isOnLine) {
response.setHeader("Content-Disposition", "inline; filename=" + URLEncoder.encode(filename, "UTF-8"));
} else {
response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(filename, "UTF-8"));
}
byte[] buffer = new byte[1024];
int len;
OutputStream outputStream = response.getOutputStream();
while ((len = inputStream.read(buffer)) > 0) {
outputStream.write(buffer, 0, len);
}
inputStream.close();
}