我做的程序gif下下来是乱码，望高手赐教！
BLOB blob = (BLOB) map.get( "HINGAZO ");

String fileName = (String) map.get( ".. ");
response.setContentType( "application/octet-stream ");
response.setHeader( "Content-Disposition ", "attachment; filename= " + fileName);

OutputStream os = response.getOutputStream();
OutputStreamWriter w = new OutputStreamWriter(os, "Shift_JIS ");
BufferedWriter writer = new BufferedWriter(w);

InputStream instream = blob.getBinaryStream();

int length;

while ((length = instream.read()) != -1) {
writer.write(length);
}

writer.close();
w.close();
os.close();
gif用文本打开，里面的数字和数据库中blob里的数字是一样的，就是每一行后边都有
乱码。是怎么回事啊？头一次做这方面的，很多都不懂 ，希望高手帮忙！谢谢！

[解决办法]
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[解决办法]
gif不是图片么？