前臺頁面請求：

window.location.href = "/download/download?fileUrl=" + data.contractUrl + "&originName=" + data.originName;

後臺下載處理：

import com.alibaba.dubbo.common.utils.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;

/**
 * 檔案下載共通實現
 *
 */
@Controller
@RequestMapping("/download")
public class DownloadController extends BaseController {

    /**
     * 日誌
     */
    private static final Logger LOGGER = LoggerFactory.getLogger(DownloadController.class);

    /**
     * 檔案下載方法實現
     *
     * @param response
     * @param fileUrl    待下載檔案路徑
     * @param originName 待下載檔案的原檔名
     */
    @RequestMapping("/download")
    public void download(HttpServletResponse response, String fileUrl, String originName) {

        // 引數不能為空，否則不支援下載
        if (StringUtils.isEmpty(fileUrl) || StringUtils.isEmpty(originName) || response == null) {
            return;
        }

        fileUrl = Constants.WEB_IMAGE_URL + fileUrl;

        // 執行下載
        ServletOutputStream sos = null;
        BufferedInputStream bis = null;
        InputStream inputStream = null;
        HttpURLConnection httpUrlConn = null;
        try {
            LOGGER.info("執行下載開始：fileUrl=" + fileUrl + ";originName=" + originName);
            // 清空response
            response.reset();
            // 設定響應頭
            response.setContentType("application/x-msdownload");
            // 重新命名為原檔名稱
            // 解決中文名稱亂碼
            originName = new String(originName.getBytes("gbk"), "iso-8859-1");
            response.addHeader("Content-Disposition", "attachment; filename=" + originName);
            // 獲取輸出流
            sos = response.getOutputStream();

            // 獲取網路路徑連線
            URL url = new URL(fileUrl);
            httpUrlConn = (HttpURLConnection) url.openConnection();
            // 設定輸入開啟
            httpUrlConn.setDoInput(true);
            // 顯性設定快取
            httpUrlConn.setUseCaches(true);
            httpUrlConn.setRequestMethod("GET");
            // 設定網路請求頭
            httpUrlConn.setRequestProperty("Content-type", "application/x-www-form-urlencoded");
            httpUrlConn.connect();

            // 通過連接獲取輸入流
            inputStream = httpUrlConn.getInputStream();
            bis = new BufferedInputStream(httpUrlConn.getInputStream());

            int i;
            // 設定下載緩衝
            /*byte[] buffer = new byte[1024];*/
            while ((i = bis.read()) != -1) {
                sos.write(i);
            }

            sos.flush();

            LOGGER.info("執行下載正常結束！");

        } catch (UnsupportedEncodingException e) {
            printLog(fileUrl, originName);
            e.printStackTrace();

        } catch (ProtocolException e) {
            printLog(fileUrl, originName);
            e.printStackTrace();

        } catch (MalformedURLException e) {
            printLog(fileUrl, originName);
            e.printStackTrace();

        } catch (IOException e) {
            printLog(fileUrl, originName);
            e.printStackTrace();
            // 關閉流
        } finally {
            closeStream(sos, bis, inputStream, httpUrlConn);
        }
    }

    /**
     * 輸出日誌
     *
     * @param fileUrl
     * @param originName
     */
    private void printLog(String fileUrl, String originName) {
        LOGGER.info("執行下載失敗：fileUrl=" + fileUrl + ";originName=" + originName);
    }

    /**
     * 關閉流
     *
     * @param sos
     * @param bis
     * @param inputStream
     * @param httpUrlConn
     */
    private void closeStream(ServletOutputStream sos, BufferedInputStream bis
            , InputStream inputStream, HttpURLConnection httpUrlConn) {
        try {
            // 釋放資源
            if (sos != null) {
                sos.close();
            }
            if (bis != null) {

                bis.close();
            }
            if (inputStream != null) {

                inputStream.close();
            }
            // 斷開連線
            if (httpUrlConn != null) {
                httpUrlConn.disconnect();
            }
        } catch (IOException ex) {
            LOGGER.info("斷開連接出錯！");
            ex.printStackTrace();
        }

    }
}