jsp下载文件方法
java.lang.IllegalStateException: getOutputStream() has already been called for this
写的jsp下载文件是这样的：
所要下载的文档在工程的webroot的pdfDoc文件，从上个网页传递的值是file，
注意：1、url传递中文值时用的是
ISO8859_1格式，所以获取编码后需要转化为utf-8
2、在jsp中使用File类，如果使用tomcat的话，默认的相对路径是tomcat下的bin文件夹，所以需要使用到绝对路径，这里使用
String path1=request. getRealPath(
"/"
);获取jsp的绝对路径
<%@
page
language
=
"java"
import
=
"java.util.*"
pageEncoding
=
"utf-8"
%><%@
page
language
=
"java"
import
=
"java.io.*,java.net.*"
%><%
String path = request.getContextPath();
String basePath = request.getScheme()+
"://"
+request.getServerName()+
":"
+request.getServerPort()+path+
"/"
;
%><%
//获得JSP页面的路径
String path1=request. getRealPath(
"/"
);
System.out.println(path1);
response.setContentType(
"text/html"
);
javax.servlet.ServletOutputStream ou = response.getOutputStream();
String filepath =
"pdfDoc/"
;
String filename =
new
String(request.getParameter(
"file"
)
.getBytes(
"ISO8859_1"
),
"utf-8"
).toString();
System.out.println(
"DownloadFile filepath:"
+ filepath);
System.out.println(
"DownloadFile filename:"
+ filename);
//java.io.File file1 = new java.io.File("t.txt");
//System.out.println(java.io.File.separator);
java.io.File file =
new
java.io.File(path1+filepath + filename);
if
(!file.exists()) {
System.out.println(file.getAbsolutePath() +
" 文件不存在!"
);
return
;
}
// 读取文件流
// 下载文件
// 设置响应头和下载保存的文件名
if
(filename !=
null
&& filename.length() > 0) {
response.setContentType(
"application/x-msdownload"
);
response.setHeader(
"Content-Disposition"
,
"attachment; filename="
+
new
String(filename.getBytes(
"utf-8"
),
"iso8859-1"
) +
""
);
java.io.FileInputStream fileInputStream =
null
;
OutputStream output =
null
;
try
{
fileInputStream =
new
java.io.FileInputStream(file);
output = response.getOutputStream();
if
(fileInputStream !=
null
) {
int
filelen = fileInputStream.available();
//文件太大时内存不能一次读出,要循环
byte
a[] =
new
byte
[1024];
int
i = 0;
while
((i = fileInputStream.read(a)) > 0) {
ou.write(a, 0, i);
}
output.flush();
}
}
catch
(Exception e) {
System.out.println(
"error"
);
e.printStackTrace();
}
finally
{
if
(fileInputStream !=
null
) {
fileInputStream.close();
}
if
(output !=
null
) {
output.close();
}
}
return
;
}
%>
<!
DOCTYPE
HTML
PUBLIC
"-//W3C//DTD HTML 4.01 Transitional//EN">
<
html
>
<
head
>
</
head
>
<
body
>
</
body
>
</
html
>
刚开始时能够下载，但是总是异常：java.lang.IllegalStateException: getOutputStream() has already been called for this
后来看了一篇文章说：<%%>和html接触的地方不要有空格说明在如下：（网址是
http://www.360doc.com/content/06/0123/16/677_61900.shtml）