Java文件下载的几种方式
public class FileDownloadUtil {
public HttpServletResponse download(String path, HttpServletResponse response) {
try {
// path是指欲下载的文件的路径。
File file = new File(path);
// 取得文件名。
String filename = file.getName();
// 取得文件的后缀名。
String ext = filename.substring(filename.lastIndexOf(".") + 1).toUpperCase();
// 以流的形式下载文件。
InputStream fis = new BufferedInputStream(new FileInputStream(path));
byte[] buffer = new byte[fis.available()];
fis.read(buffer);
fis.close();
// 清空response
response.reset();
// 设置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;
}
public void downloadLocal(HttpServletResponse response) throws FileNotFoundException {
// 下载本地文件
String fileName = "Operator.doc".toString(); // 文件的默认保存名
// 读到流中
InputStream inStream = new FileInputStream("c:/Operator.doc");// 文件的存放路径
// 设置输出的格式
response.reset();
response.setContentType("bin");
response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
// 循环取出流中的数据
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();
}
}
public void downloadNet(HttpServletResponse response) {
// 下载网络文件
int bytesum = 0;
int byteread = 0;
try {
String fileUrl = "http://oss.aliyun.cn/pro/2021/06/30/2635a51b-3338-478c-9e46-0e7834afabbb.gif";
URL url = new URL(fileUrl);
URLConnection conn = url.openConnection();
InputStream inStream = conn.getInputStream();
FileOutputStream fs = new FileOutputStream("c:/abc.gif");
byte[] buffer = new byte[8192];
int length;
while ((byteread = inStream.read(buffer)) != -1) {
bytesum += byteread;
System.out.println(bytesum);
fs.write(buffer, 0, byteread);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
支持在线打开文件的一种方式
public class FileDownloadUtil {
/**
* 支持在线打开文件的一种方式
* @param filePath
* @param response
* @param isOnLine
* @throws Exception
*/
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[8192];
int len = 0;
response.reset(); // 非常重要
if (isOnLine) { // 在线打开方式
URL u = new URL("file:///" + filePath);
response.setContentType(u.openConnection().getContentType());
response.setHeader("Content-Disposition", "inline; filename=" + f.getName());
// 文件名应该编码成UTF-8
} else { // 纯下载方式
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();
}
}
网络url下载，并写入浏览器
public class FileDownloadUtil {
/**
* 网络url下载
* @param request
* @param response
*/
public void downloadFileURL(HttpServletRequest request, HttpServletResponse response) {
String fileUrl = "http://oss.aliyun.cn/pro/2021/06/30/2635a51b-3338-478c-9e46-0e7834afabbb.pdf";
try {
URL url = new URL(fileUrl);
URLConnection conn = url.openConnection();
InputStream inStream = conn.getInputStream();
//对文件名进行编码防止中文乱码
String filename = FileDownloadUtil.encodeDownloadFilename("文件.pdf", request);
response.setContentType("application/x-msdownload");
response.setHeader("Content-Disposition", "attachment; filename=" + filename);
OutputStream out = response.getOutputStream();
byte[] buffer = new byte[8192];
int length;
while ((length = inStream.read(buffer)) != -1) {
out.write(buffer, 0, length);
}
inStream.close();
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public class FileDownloadUtil {
/**
* 下载文件时，针对不同浏览器，进行附件名的编码
*
* @param filename 载文件名
* @param request 请求request
* @return 编码后的下载附件名
* @throws IOException
*/
public static String encodeDownloadFilename(String filename, HttpServletRequest request)
throws IOException {
String agent = request.getHeader("user-agent");//获得游览器
if (agent.contains("Firefox")) { // 火狐浏览器
filename = "=?UTF-8?B?"
+ Base64.getEncoder().encode(filename.getBytes("utf-8"))
+ "?=";
filename = filename.replaceAll("\r\n", "");
} else { // IE及其他浏览器
filename = URLEncoder.encode(filename, "utf-8");
filename = filename.replace("+"," ");
}
return filename;
}
}
参考：
https://www.cnblogs.com/ungshow/archive/2009/01/12/1374491.html
