import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.URLEncoder;

import javax.servlet.http.HttpServletResponse;

import org.springframework.util.StringUtils;

/**

 * 文件下载

 */

public class FileLoad {

    /**

     * 使用response返回文件流

     */

    public void loadFile(String filePath, HttpServletResponse response) {

        // 声明工具类

        BufferedInputStream in = null;

        BufferedOutputStream out = null;

        try {

            // 若路径为空

            if (StringUtils.isEmpty(filePath)) {

                throw new Exception("invalid filepath of null.");

            }

            // 没找到文件

            File file = new File(filePath);

            if (!file.exists()) {

                throw new Exception("file not exist in path [" + filePath + "]");

            }

            // 获取文件名

            String fileName = file.getName();

            // 输出文件流到浏览器

            in = new BufferedInputStream(new FileInputStream(filePath));

            out = new BufferedOutputStream(response.getOutputStream());

            response.setContentType("application/x-download;charset=utf-8");

            response.setHeader("Content-disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));

            byte[] buffer = new byte[8192];

            int count = 0;

            while ((count = in.read(buffer, 0, 8192)) != -1) {

                out.write(buffer, 0, count);

            }

            out.flush();

            file = null;

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            closeStream(in, out);

        }

    }

    /**

     * 关闭输入输出流

     */

    public void closeStream(InputStream in, OutputStream out) {

        if (null != in) {

            try {

                in.close();

            } catch (IOException e) {

                // e.printStackTrace();

            }

        }

        if (null != out) {

            try {

                out.close();

            } catch (IOException e) {

                // e.printStackTrace();

            }

        }

    }

}