場景:使用Servlet實現檔案下載服務端
1.建立spring的web專案,確保啟動正常。
2.建立DownloadServlet類繼承HttpServlet並實現doGet方法。

public class DownloadServlet extends HttpServlet{
	
	private static final Logger logger = 
                 LoggerFactory.getLogger(DownloadServlet.class);
	private static final long serialVersionUID = 1033412753252391835L;
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		logger.info("下載開始......");
		/**1.從請求中獲取下載名稱*/
		String fileName = request.getParameter("filename");
		fileName=new String(fileName.getBytes("ISO8859-1"),"UTF-8");
		/**2.設定附件形式下載,瀏覽器根據此引數做判斷*/
		response.setHeader("Content-Disposition", "attachment;filename="+fileName);
		/**3.本地存放給服務下載的壓縮資料夾的路徑*/
		String dir = "D:/DownloadDir/";
		String filePath = dir + fileName;
		/**4.建立輸入流*/
		InputStream in=new FileInputStream(filePath);
		/**5.從response獲取輸出流*/
	    ServletOutputStream out=response.getOutputStream();
	    /**6.把輸入流寫入到輸出流,實際就是一個拷貝過程*/
	    int len=0;
        byte [] buffer=new byte[1024 * 4];
        while((len=in.read(buffer))>0) {
            out.write(buffer, 0, len);
        }
        in.close();
        out.close();
        logger.info("下載結束......");
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request,response);
	}
}
 

3.在web.xml中配置Servlet的url對映關係

    <!-- 下載服務start -->
	<servlet>
		<display-name>
		</display-name>
		<servlet-name>downloadServlet</servlet-name>
		<servlet-class>com.zbz.servlet.DownloadServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>downloadServlet</servlet-name>
		<url-pattern>/download</url-pattern>
	</servlet-mapping>
    <!-- 下載服務end -->
 

4.啟動服務在瀏覽器訪問
  本例是本地搭建服務,直接從D盤讀取一個檔案供下載,
  D:\DownloadDir\8195B04F2E924C2E9596AC79488351EF.zip
  下載url是:
  http://127.0.0.1:8080/study/download?filename=8195B04F2E924C2E9596AC79488351EF.zip
  其中: study是專案名稱
以上,TKS.