JAVA代码实现下载单个文件，和下载打包文件

//下载单个文件调用方法

/**
    * response
    * imgPath 下载图片地址
    * fileName 保存下载文件名称
    * @date 2015年4月14日 下午5:53:24
    */
    public static void download(HttpServletResponse response,String imgPath,String fileName){
         OutputStream out=null;
         BufferedInputStream br =null;
         try {
                // 设置响应类型为下载
                 response.setContentType("application/x-msdownload;charset=UTF-8");
                 //页面乱码问题
                response.setCharacterEncoding("UTF-8");
                //设置下载文件名称
                response.setHeader("Content-Disposition", "attachment; filename="+fileName);
                //输入流
                br = new BufferedInputStream(new FileInputStream(imgPath));
                byte[] buf = new byte[1024];
                int len = 0;
                out = response.getOutputStream();
                while ((len = br.read(buf)) > 0){
                      out.write(buf, 0, len);
                      out.flush();
                }
                if(null!=out) out.close();
                if(null!=br) br.close();
         } catch (Exception e) {
               e.printStackTrace();
         }
    }

//下载打包压缩文件调用方法

/**
     *files 需要下载问价的File 集合
    * @Description: TODO(文件打包下载)
    */
    public static HttpServletResponse downLoadFiles(List<File> files,
            HttpServletRequest request, HttpServletResponse response)
            throws Exception {
        try {
            ServletContext context=request.getSession().getServletContext();
            /**这个集合就是你想要打包的所有文件，
             * 这里假设已经准备好了所要打包的文件*/
            //List<File> files = new ArrayList<File>();
    
            /**创建一个临时压缩文件，
             * 我们会把文件流全部注入到这个文件中
             * 这里的文件你可以自定义是.rar还是.zip*/

File file = new File(context.getRealPath("/test.rar"));
            if (!file.exists()){
                file.createNewFile(); 
            }
            response.reset();
            //response.getWriter()
            //创建文件输出流
            FileOutputStream fous = new FileOutputStream(file);  
            /**打包的方法我们会用到ZipOutputStream这样一个输出流,
             * 所以这里我们把输出流转换一下*/
           ZipOutputStream zipOut = new ZipOutputStream(fous);
            /**这个方法接受的就是一个所要打包文件的集合，
             * 还有一个ZipOutputStream*/
            zipFile(files, zipOut);
            zipOut.close();
            fous.close();
            return downloadZip(file,response);
        }catch (Exception e) {
                e.printStackTrace();
            }
        return response ;
    }

/**
     * 把接受的全部文件打成压缩包
     * @param List<File>;
     * @param org.apache.tools.zip.ZipOutputStream
     */
    public static void zipFile(List files,ZipOutputStream outputStream) {
        int size = files.size();
        for(int i = 0; i < size; i++) {
            File file = (File) files.get(i);
            zipFile(file, outputStream);
        }
    }

public static HttpServletResponse downloadZip(File file,HttpServletResponse response) {
        try {
        // 以流的形式下载文件。
        InputStream fis = new BufferedInputStream(new FileInputStream(file.getPath()));
        byte[] buffer = new byte[fis.available()];
        fis.read(buffer);
        fis.close();
        // 清空response
        response.reset();

OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
        response.setContentType("application/octet-stream");
        response.setHeader("Content-Disposition", "attachment;filename=" + file.getName());
        toClient.write(buffer);
        toClient.flush();
        toClient.close();
        } catch (IOException ex) {
        ex.printStackTrace();
        }finally{
             try {
                    File f = new File(file.getPath());
                    f.delete();
                } catch (Exception e) {
                    e.printStackTrace();
                }
        }
        return response;
    }

/**
     * 根据输入的文件与输出流对文件进行打包
     * @param File
     * @param org.apache.tools.zip.ZipOutputStream
     */
    public static void zipFile(File inputFile,ZipOutputStream ouputStream) {
        try {
            if(inputFile.exists()) {
                /**如果是目录的话这里是不采取操作的，
                 * 至于目录的打包正在研究中*/
                if (inputFile.isFile()) {
                    FileInputStream IN = new FileInputStream(inputFile);
                    BufferedInputStream bins = new BufferedInputStream(IN, 512);
                    //org.apache.tools.zip.ZipEntry
                    ZipEntry entry = new ZipEntry(inputFile.getName());
                    ouputStream.putNextEntry(entry);
                    // 向压缩文件中输出数据  
                    int nNumber;
                    byte[] buffer = new byte[1024];
                    while ((nNumber = bins.read(buffer)) != -1) {
                        ouputStream.write(buffer, 0, nNumber);
                    }
                    // 关闭创建的流对象  
                    bins.close();
                    IN.close();
                } else {
                    try {
                        File[] files = inputFile.listFiles();
                        for (int i = 0; i < files.length; i++) {
                            zipFile(files[i], ouputStream);
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }