Java 下载文件的方法怎么写

参考下面

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", "attachmentfilename=" + 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

}

// 下载本地文件

public void downloadLocal(HttpServletResponse response) throws FileNotFoundException {

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", "attachmentfilename=\"" + 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()

}

}

// 下载网络文件

public void downloadNet(HttpServletResponse response) throws MalformedURLException {

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", "inlinefilename=" + 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", "attachmentfilename=" + f.getName())

}

OutputStream out = response.getOutputStream()

while ((len = br.read(buf)) >0)

out.write(buf, 0, len)

br.close()

out.close()

}

在jsp/servlet中断点/多线程下载文件

<%@ page import="java.io.File" %>

<%@ page import="java.io.IOException" %>

<%@ page import="java.io.OutputStream" %>

<%@ page import="java.io.RandomAccessFile" %>

<%!

    public void downloadFile(HttpServletRequest request, HttpServletResponse response, File file) throws IOException {

        RandomAccessFile raf = new RandomAccessFile(file, "r")

        java.io.FileInputStream fis = new java.io.FileInputStream(raf.getFD())

        response.setHeader("Server", "www.trydone.com")

        response.setHeader("Accept-Ranges", "bytes")

        long pos = 0

        long len

        len = raf.length()

        if (request.getHeader("Range") != null) {

            response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT)

            pos = Long.parseLong(request.getHeader("Range")

                    .replaceAll("bytes=", "")

                    .replaceAll("-", "")

            )

        }

        response.setHeader("Content-Length", Long.toString(len - pos))

        if (pos != 0) {

            response.setHeader("Content-Range", new StringBuffer()

                    .append("bytes ")

                    .append(pos)

                    .append("-")

                    .append(Long.toString(len - 1))

                    .append("/")

                    .append(len)

                    .toString()

            )

        }

        response.setContentType("application/octet-stream")

        response.setHeader("Content-Disposition", new StringBuffer()

                .append("attachmentfilename=\"")

                .append(file.getName())

                .append("\"").toString())

        raf.seek(pos)

        byte[] b = new byte[2048]

        int i

        OutputStream outs = response.getOutputStream()

        while ((i = raf.read(b)) != -1) {

            outs.write(b, 0, i)

        }

        raf.close()

        fis.close()

    }

%>

<%

    String filePath = request.getParameter("file")

    filePath = application.getRealPath(filePath)

    File file = new File(filePath)

    downloadFile(request, response, file)

%>

---