DownloadFileAction.java

DownloadFileAction.java

package com.servlet3.demo;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.Writer;

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

import org.apache.commons.io.FilenameUtils;
import org.apache.log4j.Logger;

/**
 * 文件下载演示
 * 
 * @author yongboy
 * @time 2012-1-18
 * @version 1.0
 */
@WebServlet("/down")
public class DownloadFileAction extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private final Logger log = Logger.getLogger(DownloadFileAction.class);

	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		// 传递路径用于下载
		String path = request.getParameter("path");

		long start = System.currentTimeMillis();
		downloadFile(path, null, response);
		log.info("use time : " + (System.currentTimeMillis() - start));
	}

	/**
	 * 提供一个下载的公共函数
	 * 
	 * @param filePath
	 *            文件的访问路径
	 * @param fileName
	 *            要显示的文件名称
	 * @param response
	 */
	private static void downloadFile(String filePath, String fileName,
			HttpServletResponse response) {
		if (filePath == null || filePath.trim().equals("") || response == null) {
			output(response, "请求参数有误！");
			return;
		}
		File file = new File(filePath);
		if (!file.exists() || file.isDirectory()) {
			output(response, "您请求的文件不存在或者路径有误！");
			return;
		}

		if (fileName == null || fileName.trim().equals("")) {
			fileName = FilenameUtils.getName(filePath);
		}

		try {
			// 对下载的文件名称进行编码，避免出现中文乱码问题
			response.setHeader("Content-disposition", "attachment; filename="
					+ new String(fileName.getBytes("GBK"), "ISO-8859-1"));

			InputStream is = new FileInputStream(file);
			int len = -1;
			ServletOutputStream out = response.getOutputStream();
			while ((len = is.read()) != -1) {
				out.write(len);
			}
			is.close();
			out.flush();
			out.close();
		} catch (FileNotFoundException notFound) {
			output(response, "您所请求的文件不存在！");
		} catch (IOException ioe) {
			ioe.printStackTrace();
			output(response, "您所请求的文件出现异常！");
		} catch (Exception e) {
			e.printStackTrace();
			output(response, "您所请求的文件出现异常！");
		}
	}

	private static void output(HttpServletResponse response, String message) {
		try {
			response.setContentType("text/html; charset=UTF-8");
			Writer out = response.getWriter();
			out.write(message);
			out.flush();
			out.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}