设置response响应信息即可（先将文件流转成byte[]）@RequestMapping(value = "down1", method = RequestMethod.GET)public void downloadAllClassmate(HttpServletResponse response) throws IOException {    byte[] bytes = new byte[100];    String fileName="test.pdf";    response.setContentType("application/pdf"); //设置文件格式    response.setHeader("Content-disposition", "attachment;filename=" + fileName);//设置文件名    response.setHeader("Content-Length", "102400");//设置文件大小    response.flushBuffer();    response.getOutputStream().write(bytes); //写文件到响应体重}或者采用另一种方式@RequestMapping(value = "/down2")    public ResponseEntity<byte[]> pdfDownload(HttpServletRequest httpServletRequest, HttpServletResponse response) throws IOException {        String path = "d:/c.pdf";        File file = new File(path);        HttpHeaders httpHeaders = new HttpHeaders();        String fileName = file.getName();//        设置文件名        httpHeaders.setContentDispositionFormData("attachment", java.net.URLEncoder.encode(fileName, "UTF-8"));//        设置响应格式        httpHeaders.setContentType(MediaType.parseMediaType("application/pdf"));//        将file放在ResponseEntity中返回        return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),                httpHeaders,                HttpStatus.CREATED);    }以下关于Response.ContentType 详细列表不同的ContentType 会影响客户端所看到的效果.默认的ContentType为 text/html也就是网页格式.代码如:<% response.ContentType ="text/html" %> <!--＃i nclude virtual="/ContentType.html" -->显示的为网页,而<% response.ContentType ="text/plain" %> <!--＃i nclude virtual="/sscript/ContentType.html" -->则会显示html原代码.以下为一些常用的 ContentTypeXML<% response.ContentType ="text/xml" %>GIF images<% response.ContentType ="image/gif" %> JPEG images<% response.ContentType ="image/jpeg" %> TIFF images<% response.ContentType ="image/tiff" %> <!--＃i nclude virtual="/myimage.tiff" -->MICROSOFT WORD document<% response.ContentType ="application/msword" %> <!--＃i nclude virtual="/myfile.doc" -->RTF document<% response.ContentType ="application/rtf" %> <!--＃i nclude virtual="/myfile.rtf" -->MICROSOFT EXCEL document<% response.ContentType ="application/x-excel" %> <!--＃i nclude virtual="/myfile.xls" -->MICROSOFT POWERPOINT document<% response.ContentType ="application/ms-powerpoint" %> <!--＃i nclude virtual="/myfile.pff" -->PDF document<% response.ContentType ="application/pdf" %> <!--＃i nclude virtual="/myfile.pdf" -->ZIP document<% response.ContentType ="application/zip" %> <!--＃i nclude virtual="/myfile.zip" -->下面是更详细的ContentType'ez' => 'application/andrew-inset', 'hqx' => 'application/mac-binhex40', 'cpt' => 'application/mac-compactpro', 'doc' => 'application/msword', 'bin' => 'application/octet-stream', 'dms' => 'application/octet-stream', 'lha' => 'application/octet-stream', 'lzh' => 'application/octet-stream', 'exe' => 'application/octet-stream', 'class' => 'application/octet-stream', 'so' => 'application/octet-stream', 'dll' => 'application/octet-stream', 'oda' => 'application/oda', 'pdf' => 'application/pdf', 'ai' => 'application/postscript', 'eps' => 'application/postscript', 'ps' => 'application/postscript', 'smi' => 'application/smil', 'smil' => 'application/smil', 'mif' => 'application/vnd.mif', 'xls' => 'application/vnd.ms-excel', 'ppt' => 'application/vnd.ms-powerpoint', 'wbxml' => 'application/vnd.wap.wbxml', 'wmlc' => 'application/vnd.wap.wmlc', 'wmlsc' => 'application/vnd.wap.wmlscriptc', 'bcpio' => 'application/x-bcpio', 'vcd' => 'application/x-cdlink', 'pgn' => 'application/x-chess-pgn', 'cpio' => 'application/x-cpio', 'csh' => 'application/x-csh', 'dcr' => 'application/x-director', 'dir' => 'application/x-director', 'dxr' => 'application/x-director', 'dvi' => 'application/x-dvi', 'spl' => 'application/x-futuresplash', 'gtar' => 'application/x-gtar', 'hdf' => 'application/x-hdf', 'js' => 'application/x-javascript', 'skp' => 'application/x-koan', 'skd' => 'application/x-koan', 'skt' => 'application/x-koan', 'skm' => 'application/x-koan', 'latex' => 'application/x-latex', 'nc' => 'application/x-netcdf', 'cdf' => 'application/x-netcdf', 'sh' => 'application/x-sh', 'shar' => 'application/x-shar', 'swf' => 'application/x-shockwave-flash', 'sit' => 'application/x-stuffit', 'sv4cpio' => 'application/x-sv4cpio', 'sv4crc' => 'application/x-sv4crc', 'tar' => 'application/x-tar', 'tcl' => 'application/x-tcl', 'tex' => 'application/x-tex', 'texinfo' => 'application/x-texinfo', 'texi' => 'application/x-texinfo', 't' => 'application/x-troff', 'tr' => 'application/x-troff', 'roff' => 'application/x-troff', 'man' => 'application/x-troff-man', 'me' => 'application/x-troff-me', 'ms' => 'application/x-troff-ms', 'ustar' => 'application/x-ustar', 'src' => 'application/x-wais-source', 'xhtml' => 'application/xhtml+xml', 'xht' => 'application/xhtml+xml', 'zip' => 'application/zip', 'au' => 'audio/basic', 'snd' => 'audio/basic', 'mid' => 'audio/midi', 'midi' => 'audio/midi', 'kar' => 'audio/midi', 'mpga' => 'audio/mpeg', 'mp2' => 'audio/mpeg', 'mp3' => 'audio/mpeg', 'aif' => 'audio/x-aiff', 'aiff' => 'audio/x-aiff', 'aifc' => 'audio/x-aiff', 'm3u' => 'audio/x-mpegurl', 'ram' => 'audio/x-pn-realaudio', 'rm' => 'audio/x-pn-realaudio', 'rpm' => 'audio/x-pn-realaudio-plugin', 'ra' => 'audio/x-realaudio', 'wav' => 'audio/x-wav', 'pdb' => 'chemical/x-pdb', 'xyz' => 'chemical/x-xyz', 'bmp' => 'image/bmp', 'gif' => 'image/gif', 'ief' => 'image/ief', 'jpeg' => 'image/jpeg', 'jpg' => 'image/jpeg', 'jpe' => 'image/jpeg', 'png' => 'image/png', 'tiff' => 'image/tiff', 'tif' => 'image/tiff', 'djvu' => 'image/vnd.djvu', 'djv' => 'image/vnd.djvu', 'wbmp' => 'image/vnd.wap.wbmp', 'ras' => 'image/x-cmu-raster', 'pnm' => 'image/x-portable-anymap', 'pbm' => 'image/x-portable-bitmap', 'pgm' => 'image/x-portable-graymap', 'ppm' => 'image/x-portable-pixmap', 'rgb' => 'image/x-rgb', 'xbm' => 'image/x-xbitmap', 'xpm' => 'image/x-xpixmap', 'xwd' => 'image/x-xwindowdump', 'igs' => 'model/iges', 'iges' => 'model/iges', 'msh' => 'model/mesh', 'mesh' => 'model/mesh', 'silo' => 'model/mesh', 'wrl' => 'model/vrml', 'vrml' => 'model/vrml', 'css' => 'text/css', 'html' => 'text/html', 'htm' => 'text/html', 'asc' => 'text/plain', 'txt' => 'text/plain', 'rtx' => 'text/richtext', 'rtf' => 'text/rtf', 'sgml' => 'text/sgml', 'sgm' => 'text/sgml', 'tsv' => 'text/tab-separated-values', 'wml' => 'text/vnd.wap.wml', 'wmls' => 'text/vnd.wap.wmlscript', 'etx' => 'text/x-setext', 'xsl' => 'text/xml', 'xml' => 'text/xml', 'mpeg' => 'video/mpeg', 'mpg' => 'video/mpeg', 'mpe' => 'video/mpeg', 'qt' => 'video/quicktime', 'mov' => 'video/quicktime', 'mxu' => 'video/vnd.mpegurl', 'avi' => 'video/x-msvideo', 'movie' => 'video/x-sgi-movie', 'ice' => 'x-conference/x-cooltalk'

封装的工具类，get下载调用downloadURL(url)，post下载调用POSTMethod()import org.apache.commons.collections.MapUtils;import org.apache.commons.lang3.StringUtils;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.client.HttpClient;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.entity.BufferedHttpEntity;import org.apache.http.entity.ByteArrayEntity;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.message.BasicNameValuePair;import java.io.ByteArrayOutputStream;import java.util.*;/** * User: Cheng * Date: 2019/4/22 * Time: 17:33 * Description: No Description */public class PostUtil {    /**     * 以Post方法访问     *     * @param url     请求地址     * @param argsMap 携带的参数     * @param content 内容     * @return String 返回结果     * @throws Exception     */    public static byte[] POSTMethod(String url, Map<String, Object> argsMap, String content) throws Exception {//        argsMap，content都可以带参，二选一        byte[] dataByte = null;        HttpClient httpClient = new DefaultHttpClient();        HttpPost httpPost = new HttpPost(url);        if (MapUtils.isNotEmpty(argsMap)) {            //设置参数            UrlEncodedFormEntity encodedFormEntity = new UrlEncodedFormEntity(setHttpParams(argsMap), "UTF-8");            httpPost.setEntity(encodedFormEntity);        }        if (StringUtils.isNotEmpty(content)) {            httpPost.setEntity(new ByteArrayEntity(content.getBytes()));        }        // 执行请求        HttpResponse httpResponse = httpClient.execute(httpPost);        // 获取返回的数据        HttpEntity httpEntity = httpResponse.getEntity();        if (httpEntity != null) {            byte[] responseBytes = getData(httpEntity);            dataByte = responseBytes;            httpPost.abort();        }        //将字节数组转换成为字符串//        String result = bytesToString(dataByte);//        return result;        return dataByte;    }    /**     * 获取Entity中数据     *     * @param httpEntity     * @return     * @throws Exception     */    public static byte[] getData(HttpEntity httpEntity) throws Exception {        BufferedHttpEntity bufferedHttpEntity = new BufferedHttpEntity(httpEntity);        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();        bufferedHttpEntity.writeTo(byteArrayOutputStream);        byte[] responseBytes = byteArrayOutputStream.toByteArray();        return responseBytes;    }    /**     * 设置HttpPost请求参数     * @param argsMap     * @return BasicHttpParams     */    private static List<BasicNameValuePair> setHttpParams(Map<String, Object> argsMap){        List<BasicNameValuePair> nameValuePairList = new ArrayList<BasicNameValuePair>();        //设置请求参数        if (argsMap!=null && !argsMap.isEmpty()) {            Set<Map.Entry<String, Object>> set = argsMap.entrySet();            Iterator<Map.Entry<String, Object>> iterator = set.iterator();            while(iterator.hasNext()){                Map.Entry<String, Object> entry = iterator.next();                BasicNameValuePair basicNameValuePair = new BasicNameValuePair(entry.getKey(), entry.getValue().toString());                nameValuePairList.add(basicNameValuePair);            }        }        return nameValuePairList;    }    public static byte[] downloadURL(String url) throws Exception {        byte[] dataByte = null;        HttpClient httpClient = new DefaultHttpClient();        HttpGet httpGet = new HttpGet(url);        HttpResponse httpResponse = httpClient.execute(httpGet);        HttpEntity entity = httpResponse.getEntity();//获取返回数据        if (entity != null) {//            根据entity创建BufferedHttpEntity与创建流对象            BufferedHttpEntity bufferedHttpEntity = new BufferedHttpEntity(entity);            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();//          将BufferedHttpEntity写到流中            bufferedHttpEntity.writeTo(byteArrayOutputStream);//            将流转换成byte[]            byte[] responseBytes = byteArrayOutputStream.toByteArray();            dataByte = responseBytes;            httpGet.abort();    //（终止）程序        }        return dataByte;    }}