import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;

import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;

public class DownLoadUtil {
    private static Logger logger = Logger.getLogger(DownLoadUtil.class);
    /**
     * 下载文件
     * @param name 用户下载的文件名(*****.***)
     * @param filePath 文件路径
     * @param response 
     * @param fileType 文件类型
     * @return
     * @throws Exception
     */
    public static boolean downLoadFile(String name,String filePath,
            HttpServletResponse response, String fileType)
            throws Exception {
        logger.info("start invoke downLoadFile,[filePath:"+filePath+" , fileType:"+fileType+"]");
        File file = new File(filePath);
        //设置文件类型
        if("pdf".equals(fileType)){
            response.setContentType("application/pdf");
        }else if("xls".equals(fileType)){
            response.setContentType("application/msexcel");
        }else if("doc".equals(fileType)){
            response.setContentType("application/msword");
        }
        response.setHeader("Content-Disposition", "attachment;filename=\""
                + new String(name.getBytes("GB2312"), "ISO8859-1") + "\"");
        //response.setHeader("Content-Disposition", "attachment;filename=\""+ URLEncoder.encode(name, "UTF-8")+ "\"");
        response.setContentLength((int) file.length());
        byte[] buffer = new byte[4096];// 缓冲区
        BufferedOutputStream output = null;
        BufferedInputStream input = null;
        try {
            output = new BufferedOutputStream(response.getOutputStream());
            input = new BufferedInputStream(new FileInputStream(file));
            int n = -1;
            while ((n = input.read(buffer, 0, 4096)) > -1) {
                output.write(buffer, 0, n);
            }
            output.flush();
            response.flushBuffer();
        } catch (Exception e) {
            logger.error("exception when invoke downLoadFile",e);
            throw e;
        } finally {
            if (input != null)
                input.close();
            if (output != null)
                output.close();
        }
        logger.info("end invoke downLoadFile!");
        return true;
    }
}