文件下载服务端代码示例

package com.yonyou.uap.um.servlet;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.yonyou.uap.um.context.util.UmContextUtil;
import com.yonyou.uap.um.context.util.UmContextUtil.FsOperator;
import com.yonyou.uap.um.filestore.UmFileStoreException;
import com.yonyou.uap.ump.log.UmpLogger;
import com.yonyou.uap.ump.util.MAHomeFactory;
public class DownloadServlet extends HttpServlet {
    private static final long serialVersionUID = 5009692626436714447L;
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String user = UmContextUtil.handleNULLStr(req.getParameter(UmContextUtil.KEY_USER));
        user = new String(user.getBytes("ISO-8859-1"), "UTF-8");
        String appid = UmContextUtil.handleNULLStr(req.getParameter(UmContextUtil.KEY_APPID));
        appid = new String(appid.getBytes("ISO-8859-1"), "UTF-8");
        String token = UmContextUtil.handleNULLStr(req.getParameter(UmContextUtil.KEY_TOKEN));
        token = new String(token.getBytes("ISO-8859-1"), "UTF-8");
        String devid = UmContextUtil.handleNULLStr(req.getParameter(UmContextUtil.KEY_DEVID));
        devid = new String(devid.getBytes("ISO-8859-1"), "UTF-8");
        String fileName = UmContextUtil.handleNULLStr(req.getParameter(UmContextUtil.KEY_FILENAME));
        fileName = java.net.URLDecoder.decode(fileName, "ISO-8859-1");
        fileName = new String(fileName.getBytes("ISO-8859-1"), "UTF-8");
        if (fileName != null && !"".equalsIgnoreCase(fileName)) {
            String maHome = MAHomeFactory.MA_HOME;
            String fileDir = maHome + File.separator + "UPLOAD";
            try {
                downloadFile(fileDir, user, appid, resp, fileName);
            } catch (Exception e) {
                UmpLogger.error(e.getMessage());
            }
        }
    }
    /**
     * download file for download servlet
     * 
     * @param dir
     * @param user
     * @param appid
     * @param response
     * @param fileName
     * @throws Exception
     */
    public static Map<String, Object> downloadFile(String dir, String user, String appid, HttpServletResponse response, String fileName) throws Exception {
        if (fileName == null || "".equalsIgnoreCase(fileName)) {
            return null;
        }
        OutputStream output = null;
        try {
            response.setContentType("application/x-download");
            response.addHeader("Content-Disposition", "attachment;filename=" + new String(fileName.getBytes("UTF-8"), "ISO8859_1"));
            response.setCharacterEncoding("UTF-8");
            // 获得输出流
            output = response.getOutputStream();
            // 写入文件流
            //...
            Map map = new HashMap();
            map.put("appid", appid);
            map.put("filename", filename);
            map.put("params", params);
            map.put("hostURI", getHostUri());
            byte[] bytes = ((ByteArrayOutputStream) output).toByteArray();
            byte[] bese64Bytes = Base64.encodeBase64(bytes);
            map.put(MAUtil.UPLOAD_KEY_FIELDS, new String(bese64Bytes));
            return map;
        } catch (Exception e) {
            throw new UmFileStoreException("um download file exception", e);
        } finally {
            try {
                if (output != null) {
                    output.close();
                    output = null;
                }
            } catch (Exception e) {
                throw new UmFileStoreException( "um file stream close exception", e);
            }
        }
    }
}