本文实例为大家分享了Servlet实现文件下载的具体代码，供大家参考，具体内容如下
把文件目录直接暴露给用户是很不安全的。所以要用Servlet来做，而且这样做，文件的存储方式就更丰富了，可以是从文件系统上取来的，也可以是数据库中经过计算生成的，或者从其它什么稀奇古怪的地方取来的。
public class DownloadServlet extends HttpServlet { private String contentType = "application/x-msdownload"; private String enc = "utf-8"; private String fileRoot = ""; /** * 初始化contentType，enc，fileRoot */ public void init(ServletConfig config) throws ServletException { String tempStr = config.getInitParameter("contentType"); if (tempStr != null && !tempStr.equals("")) { contentType = tempStr; } tempStr = config.getInitParameter("enc"); if (tempStr != null && !tempStr.equals("")) { enc = tempStr; } tempStr = config.getInitParameter("fileRoot"); if (tempStr != null && !tempStr.equals("")) { fileRoot = tempStr; } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String filepath = request.getParameter("filepath"); String fullFilePath = fileRoot + filepath; /*读取文件*/ File file = new File(fullFilePath); /*如果文件存在*/ if (file.exists()) { String filename = URLEncoder.encode(file.getName(), enc); response.reset(); response.setContentType(contentType); response.addHeader("Content-Disposition", "attachment; filename=/"" + filename + "/""); int fileLength = (int) file.length(); response.setContentLength(fileLength); /*如果文件长度大于0*/ if (fileLength != 0) { /*创建输入流*/ InputStream inStream = new FileInputStream(file); byte[] buf = new byte[4096]; /*创建输出流*/ ServletOutputStream servletOS = response.getOutputStream(); int readLength; while (((readLength = inStream.read(buf)) != -1)) { servletOS.write(buf, 0, readLength); } inStream.close(); servletOS.flush(); servletOS.close(); } } }web.xml
<servlet> <servlet-name>downloadservlet-name> <servlet-class>org.mstar.servlet.DownloadServletservlet-class> <init-param> <param-name>fileRootparam-name> <param-value>d:/tempparam-value> init-param> <init-param> <param-name>contentTypeparam-name> <param-value>application/x-msdownloadparam-value> init-param> <init-param> <param-name>encparam-name> <param-value>utf-8param-value> init-param> servlet> <servlet-mapping> <servlet-name>downloadservlet-name> <url-pattern>/downurl-pattern> servlet-mapping>
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。