<servlet>
	<servlet-name>DownLoadServlet</servlet-name>
		<servlet-class>com.file.DownLoadServlet</servlet-class>
		<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>DownLoadServlet</servlet-name>
		<url-pattern>/DownLoadServlet</url-pattern>
	</servlet-mapping>

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;

public class DownLoadServlet extends HttpServlet {
	Logger logger = Logger.getLogger(DownLoadServlet.class);
	public DownLoadServlet() {
		super();
	}

	public void destroy() {
		super.destroy();
	}

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

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		logger.info("下载开始");
		String root = getServletContext().getRealPath("/");
		String path = "download/";
		String name = java.net.URLEncoder.encode("物联健身私教 1.0.apk", "UTF-8");
		name = name.replaceAll("\\+", "%20");
		name = new String(name.getBytes("iso8859-1"), "gb2312");
		response.setContentType("application/x-msdownload");
		response.setHeader("Content-disposition", "attachment; filename="
				+ name);


		// 处理请求
		// 读取要下载的文件
		File f = new File(root + path + name);
		if (f.exists()) {
			FileInputStream fis = new FileInputStream(f);
			String filename = URLEncoder.encode(f.getName(), "utf-8"); // 解决中文文件名下载后乱码的问题
			byte[] b = new byte[fis.available()];
			fis.read(b);
			response.setCharacterEncoding("utf-8");
			response.setHeader("Content-Disposition", "attachment; filename="
					+ filename + "");
			// 获取响应报文输出流对象
			ServletOutputStream out = response.getOutputStream();
			// 输出
			out.write(b);
			out.flush();
			out.close();
		}

	}
	/**
	 * Initialization of the servlet. <br>
	 * 
	 * @throws ServletException
	 *             if an error occurs
	 */
	public void init() throws ServletException {

	}

}