java下载文件的几种方式

时间:2021-01-24 20:04:16

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
        } 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();
    }
转自:http://www.cnblogs.com/ungshow/archive/2009/01/12/1374491.html