getWriter() has already been called for this response的解决办法

Servlet规范说明，不能既调用 response.getOutputStream()，又调用response.getWriter()，无论先调用哪一个，在调用第二个时候应会抛出 IllegalStateException


对于getOutputStream()，api里是这样说的：Either this method or getWriter() may be called to write the body, not both.

也就是getOutputStream()和getWriter() 只能使用一个，把代码里的response.getOutputStream()全部删之后，统一使用response.getWriter() 作为输出流，问题解决。

全部代码如下


response.setContentType( "application/octet-stream ");
response.addHeader("Content-Disposition","attachment;filename=" + "work.xls");
java.io.FileInputStream fileInputStream = null;
ServletOutputStream sos = null;
PrintWriter writer = null;
try
{
fileInputStream = new java.io.FileInputStream(file);
writer = response.getWriter();
response.getOutputStream();
int i;
while((i = fileInputStream.read()) != -1)
{
writer.write(i);
}
writer.flush();
}
catch (FileNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
finally
{
if(sos != null)
{
try
{
sos.close();
}
catch(IOException e)
{
e.printStackTrace();
}
}
if(fileInputStream != null)
{
try
{
fileInputStream.close();
}
catch(IOException e)
{
e.printStackTrace();
}
}
if(writer != null)
{
writer.close();
}
}

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