@RequestMapping("/download")    public String download(String fileName, HttpServletRequest request,            HttpServletResponse response) {        response.setCharacterEncoding("utf-8");        response.setContentType("multipart/form-data");        response.setHeader("Content-Disposition", "attachment;fileName="                + fileName);        try {            String path = Thread.currentThread().getContextClassLoader()                    .getResource("").getPath()                    + "download";//这个download目录为啥建立在classes下的            InputStream inputStream = new FileInputStream(new File(path                    + File.separator + fileName));            OutputStream os = response.getOutputStream();            byte[] b = new byte[2048];            int length;            while ((length = inputStream.read(b)) > 0) {                os.write(b, 0, length);            }             // 这里主要关闭。            os.close();            inputStream.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }            //  返回值要注意，要不然就出现下面这句错误！            //java+getOutputStream() has already been called for this response        return null;    }

package com.clj.test.down.util;    import java.io.File;  import java.io.IOException;    import org.apache.commons.io.FileUtils;  import org.springframework.context.annotation.Scope;  import org.springframework.http.HttpHeaders;  import org.springframework.http.HttpStatus;  import org.springframework.http.MediaType;  import org.springframework.http.ResponseEntity;  import org.springframework.stereotype.Component;  import org.springframework.web.bind.annotation.RequestMapping;    /**  * <一句话功能简述>  * <功能详细描述>  *   * @author  Administrator  * @version  [版本号, 2014年3月7日]  * @see  [相关类/方法]  * @since  [产品/模块版本]  */  @Component  @Scope("prototype")   @RequestMapping("/downloadFile")  public class DownloadAction  {        @RequestMapping("download")        public ResponseEntity<byte[]> download() throws IOException {            String path="D:\\workspace\\.metadata\\.plugins\\org.eclipse.wst.server.core\\tmp0\\wtpwebapps\\springMVC\\WEB-INF\\upload\\图片10（定价后）.xlsx";          File file=new File(path);          HttpHeaders headers = new HttpHeaders();            String fileName=new String("你好.xlsx".getBytes("UTF-8"),"iso-8859-1");//为了解决中文名称乱码问题          headers.setContentDispositionFormData("attachment", fileName);           headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);           return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),                                              headers, HttpStatus.CREATED);        }    }