文件名称：domain/config/mimemappings.properties   
  

js=text/javascript   
css=text/css   
gif=image/gif   
htm=text/html   
html=text/html   
jpeg=image/jpeg   
jpg=image/jpeg   
bmp=image/bmp

可在此文件中加入自已需要的内容。 

个人觉得设置完后，Weblogic可能要重启一下。 

从OTN上找到点儿文字，好像有点用： 
问题：WebLogic Server Does Not Set MIME Content-Type 

WebLogic Server does not set content-type for files with .js and .xml extensions. 

To work around this issue, you have to configure these mime types in your environment using one of the following two methods: 

Method 1 

Add these mime types in the web.xml file of the ESB Web Application. 

Method 2 

Set the mime type for the entire domain in the config/mimemapping.properties file by performing the following steps: 

Login to the WebLogic Server console at 

http://hostname:port/console 

Click Domain, then Configuration, and then Web Applications. 

Search for the Mime parameter. 

The value of this parameter shows the location of the mimemappings.properties file. 

Create the mimemappings.properties file if the file is not present already. 

Add the following entries in the mimemappings.properties file: 

xml=text/xml 
js=text/javascript 
Restart

--转自