缺省类型
text/plain

预定义类型
java=text/plain
html=text/html
body=text/html
txt=text/plain
class=application/java
src=application/x-wais-source
zip=application/zip
tar=application/x-tar
bin=application/octet-stream
pdf=application/pdf
exe=application/octet-stream
//图片类型
gif=image/gif
...
//音频类型
au=audio/basic
...
//视频类型
mpeg=video/mpeg
...
//扩展类型
perl=application/x-perl