Java下載檔案的幾種方式
阿新 • • 發佈:2018-12-31
1.以流的方式下載
public HttpServletResponse download(String path, HttpServletResponse response) { try { // path是指欲下載的檔案的路徑。 File file = new File(path); // 取得檔名。 String filename = file.getName(); // 取得檔案的字尾名。 String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase(); // 以流的形式下載檔案。 InputStream fis = new BufferedInputStream(new FileInputStream(path)); byte[] buffer = new byte[fis.available()]; fis.read(buffer); fis.close(); // 清空response response.reset(); // 設定response的Header response.addHeader("Content-Disposition", "attachment;filename=" + new String(filename.getBytes())); response.addHeader("Content-Length", "" + file.length()); OutputStream toClient = new BufferedOutputStream(response.getOutputStream()); response.setContentType("application/octet-stream"); toClient.write(buffer); toClient.flush(); toClient.close(); } catch (IOException ex) { ex.printStackTrace(); } return response; }
2.下載本地檔案
public void downloadLocal(HttpServletResponse response) throws FileNotFoundException { // 下載本地檔案 String fileName = "Operator.doc".toString(); // 檔案的預設儲存名 // 讀到流中 InputStream inStream = new FileInputStream("c:/Operator.doc");// 檔案的存放路徑 // 設定輸出的格式 response.reset(); response.setContentType("bin"); response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\""); // 迴圈取出流中的資料 byte[] b = new byte[100]; int len; try { while ((len = inStream.read(b)) > 0) response.getOutputStream().write(b, 0, len); inStream.close(); } catch (IOException e) { e.printStackTrace(); } }
3.下載網路檔案
public void downloadNet(HttpServletResponse response) throws MalformedURLException { // 下載網路檔案 int bytesum = 0; int byteread = 0; URL url = new URL("windine.blogdriver.com/logo.gif"); try { URLConnection conn = url.openConnection(); InputStream inStream = conn.getInputStream(); FileOutputStream fs = new FileOutputStream("c:/abc.gif"); byte[] buffer = new byte[1204]; int length; while ((byteread = inStream.read(buffer)) != -1) { bytesum += byteread; System.out.println(bytesum); fs.write(buffer, 0, byteread); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } }
4.支援線上開啟的方式
public void downLoad(String filePath, HttpServletResponse response, boolean isOnLine) throws Exception {
File f = new File(filePath);
if (!f.exists()) {
response.sendError(404, "File not found!");
return;
}
BufferedInputStream br = new BufferedInputStream(new FileInputStream(f));
byte[] buf = new byte[1024];
int len = 0;
response.reset(); // 非常重要
if (isOnLine) { // 線上開啟方式
URL u = new URL("file:///" + filePath);
response.setContentType(u.openConnection().getContentType());
response.setHeader("Content-Disposition", "inline; filename=" + f.getName());
// 檔名應該編碼成UTF-8
} else { // 純下載方式
response.setContentType("application/x-msdownload");
response.setHeader("Content-Disposition", "attachment; filename=" + f.getName());
}
OutputStream out = response.getOutputStream();
while ((len = br.read(buf)) > 0)
out.write(buf, 0, len);
br.close();
out.close();
}