java下载

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
        } 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();
    }

以上原文地址：http://blog.csdn.net/yu444/archive/2010/12/29/6104521.aspx

自己在用的一种超链接下载方式：

html页面：

<script >

 //为了下载添加的

 function SaveToLocal() { 

 var pathss=document.getElementById("pathValueHidden").value;
if(pathss.lastIndexOf(".")==-1){

  alert("此文件不存在");

return;

 }else{

 var src ="page/pagel.jsp?path="+pathss; 
document.getElementById("ModifyCameraForm").src = src;  }
}
</script>

<a  href="javascript:void(0)" onclick='SaveToLocal()'>

page.jsp页面：

<%@ page contentType="text/html; charset=utf-8"%>

<%@ page language="java" import="java.io.IOException,java.io.FileOutputStream,java.io.File,java.io.InputStream,java.net.URL,java.net.URLConnection,java.io.OutputStream" pageEncoding="utf-8"%>

<%

//request.setCharacterEncoding("gb2312");

String path = request.getParameter("path"); //ftp路径url//
String name=path.substring(path.lastIndexOf("/")+1,

path.length());

path = new String(path.getBytes("UTF-8"),"UTF-8"); 
response.setHeader("Content-Disposition", "attachment; filename=" + java.net.URLEncoder.encode(name, "UTF-8")); //modify20100303String strUrl = path;

URLConnection uc = null;
try {URL url = new URL(strUrl);

uc = url.openConnection();

uc.setRequestProperty("User-Agent",  "Mozilla/4.0 (compatible; MSIE 5.0; Windows XP; DigExt)");  

//uc.setReadTimeout(30000);//获取图片长度  //System.out.println("Content-Length: "+uc.getContentLength()); //获取文件头信息

//System.out.println("Header"+uc.getHeaderFields().toString());  

// if (uc == null)

// return 0;

InputStream ins = uc.getInputStream(); 

byte[] str_b = new byte[1024];  

int byteRead=0;String[] images=strUrl.split("/");

//String imagename=images[images.length-1];

OutputStream fos = response.getOutputStream();

while ((byteRead=ins.read(str_b)) > 0) {

fos.write(str_b,0,byteRead);

};

fos.flush();  

fos.close();}

catch (Exception e) {

e.printStackTrace();

//log.error("获取网页内容出错");

}finally{uc = null;

}
%>

原文地址忘掉啦是在csdn上面的，sorry原作者：以上是我小该了一部分，直接传完整的path就可以啦

以下是另外的一个人的写法原文地址http://long5534.iteye.com/blog/139468

%@ page contentType="text/html;charset=utf-8" %>
<%@ page import = "java.util.*" %>
<%@ page import = "java.io.*" %>
<%@ page import = "java.net.*" %>
<%
//防止IE缓存
response.setHeader("pragma","no-cache");
response.setHeader("cache-control","no-cache");
response.setDateHeader("Expires",0);
//设置编码
request.setCharacterEncoding("UTF-8");

String fileName = request.getParameter("fileName");
//取到文件
File file = new File(application.getRealPath("/")+"upload/" + fileName);
response.reset();
//response.setContentType("application/octet-stream;charset=UTF-8");
response.setContentType("application/octet-stream;charset=GBK");//解决在弹出文件下载框不能打开文件的问题
//System.out.println(response.getCharacterEncoding());
//一定要对fileName进行encode
//response.addHeader("Content-Disposition", "attachment; filename=" + java.net.URLEncoder.encode(fileName, "UTF-8"));
response.addHeader("Content-Disposition", "attachment; filename=" + new String(fileName.getBytes("GBK"),"ISO8859-1"));//解决在弹出文件下载框不能打开文件的问题
response.setContentLength((int) file.length());

byte[] buffer = new byte[4096];
BufferedOutputStream output = null;
BufferedInputStream input = null;

// 写缓冲区：
try {
    output = new BufferedOutputStream(response.getOutputStream());
    input = new BufferedInputStream(new FileInputStream(file));

    int n = (-1);
    while ((n = input.read(buffer, 0, 4096)) > -1) {
        output.write(buffer, 0, n);
    }
    response.flushBuffer();
}
catch (Exception e) {
} // maybe user cancelled download
finally {
    if (input != null) input.close();
    if (output != null) output.close();
}
%>