java流下载

/**
	 * <p>功能:下载apk</p>
	 * @author 周枫
	 * @date 2013-5-29
	 * @param 
	 * @return void
	 */
	public void bagDownloadApk() throws Exception
	{
		String fileName = "";
		String filePath = "";
		List<HashMap> list = new ArrayList<HashMap>();
		list = teachUpdateService.selectApkInfo();
		for (int i = 0; i < list.size(); i++) {
			fileName = list.get(i).get("APK_NAME").toString();
			filePath = list.get(i).get("APK_PATH").toString();
		}
		filePath = filePath + fileName;
		// 打开指定文件的流信息
		java.io.FileInputStream fs = null;
		try {
			fs = new java.io.FileInputStream(new java.io.File(filePath));
		} catch (java.io.FileNotFoundException e) {
			e.printStackTrace();
		}
		// 设置响应头和保存文件名
		response.setContentType("APPLICATION/OCTET-STREAM");
		response.setHeader("Content-Disposition", "attachment; filename=\""
				+ fileName + "\"");
		// 写出流信息
		int b = 0;
		try {
			java.io.PrintWriter out = response.getWriter();
			while ((b = fs.read()) != -1) {
				out.write(b);
			}
			fs.close();
			out.close();
			System.out.println("文件下载完毕.");
		} catch (Exception e) {
			e.printStackTrace();
			System.out.println("下载文件失败!");
		} finally {
			if(null != fs){
				fs.close();
			}
		}
	}