文件下载取消保存下载异常

Caused by: java.net.SocketException: Connection reset by peer: socket write error
	at java.net.SocketOutputStream.socketWrite0(Native Method)
	at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:92)
	at java.net.SocketOutputStream.write(SocketOutputStream.java:136)
	at org.apache.coyote.http11.InternalOutputBuffer.realWriteBytes(InternalOutputBuffer.java:737)
	at org.apache.tomcat.util.buf.ByteChunk.flushBuffer(ByteChunk.java:434)
	at org.apache.coyote.http11.InternalOutputBuffer.flush(InternalOutputBuffer.java:299)
	at org.apache.coyote.http11.Http11Processor.action(Http11Processor.java:963)
	at org.apache.coyote.Response.action(Response.java:183)
	at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:314)
	... 26 more
2012-12-14 9:22:13 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet action threw exception
java.lang.IllegalStateException: Cannot forward after response has been committed
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:302)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:292)
	at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
	at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:398)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:241)
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
	at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        ......................

下载代码: 
 
            os = response.getOutputStream();  
            is = new FileInputStream(new File("download.wmv"));
             
            response.reset();  
            String fileName = "download.wmv"
            response.setHeader("Content-disposition", "attachment;filename =" + new String(fileName.getBytes("GBK"),"ISO8859-1")); 
            
            int length= 0;  
            byte[] buffer = new byte[1024];  
            while((length= is.read(buffer,0,1024)) != -1){  
                os.write(buffer, 0, length);  
            }
            os.flush();
            is.close();
            os.close();

异常现状：点击下载，不保存文件，直接点取消，IE 下取消上面异常。
解决方案：os.flush(); 代码位置移到 byte[] buffer = new byte[1024]; 缓冲write(...)之前