下载文件

JaneLan

protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {

try {
String filePath = this.getServletContext().getRealPath("/")
+ "/Help.chm";
if (req.getSession().getAttribute(Constants.USER_IN_SESSION) == null) {
String encode = (String) req.getSession()
.getAttribute("encode");
resp.sendRedirect(req.getContextPath() + "/login.jsp?encode="
+ encode);
} else {
try {
downLoad(filePath, resp, true);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} catch (Exception e) {
System.out.println("Error!");
e.printStackTrace();
}
}

protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(req, resp);
}

public void downLoad(String filePath, HttpServletResponse response,
boolean isOnLine) throws Exception {
try {
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();

} catch (Exception e) {
System.out.println("下载错误");
e.printStackTrace();
}
}