Java文件下载的几种方式

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) throws MalformedURLException {
// 下载网络文件
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();
}
}
//支持在线打开文件的一种方式
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) { // 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  Java中文网:http://www.javaweb.cc
} 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();
}