String s1=transUrl; // transUrl是前臺接受的引數,get接受的引數tomcat一律使用iso-8859-1編碼

transUrl=new String(transUrl.getBytes("ISO-8859-1"),"utf-8");//程式中要使用的檔名，必須轉換為gbk編碼
s1=s1.substring(6);
s1=s1.substring(s1.indexOf("/"));
String filename=s1.substring(s1.lastIndexOf("/")+1);
String filepath=s1.substring(0,s1.lastIndexOf("/"));

response.setCharacterEncoding("gbk");
response.setContentType("application/octet-stream");
response.addHeader("Content-Disposition", "attachment;filename=\"" + new String(filename.getBytes("gbk"),"ISO-8859-1")+ "\"");//response檔案頭中定義的filename包含的中文必須是原始的ISO-8859-1編碼。

boolean suc=false;
suc=downFileStream("10.0.2.1", 21,"myUser","myPwd",
filepath, filename, os);//downFileStream是一個下載ftp檔案到檔案流的方法
if(!suc){
response.reset();
response.setCharacterEncoding("gbk");
PrintWriter writer=new PrintWriter(os);
writer.write("指定的檔案不存在!");
writer.close();
}else{
os.close();
};