downloadservlet.java

weblogic+j2ee构建音乐网站(原代码＋数据库) src.zip: Workshop 8.1 工程 db.zip: 数据库备份

package music.web; 

import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;
import music.web.MusicViewBD;

/**
 * use like this:
 * http://ip-address/url-mapping?id=###
 */
public class DownloadServlet extends HttpServlet {

    private static String prefix = null;

    public void init(ServletConfig config) throws ServletException {
        // 获得文件起始路径:
        prefix = config.getInitParameter("prefix");
        if(prefix==null) prefix = "";
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException
    {
        int id = 0;
        try {
            id = Integer.parseInt(request.getParameter("id"));
        }
        catch(Exception e) {
            throw new ServletException("Parameter expected.");
        }

        String url = null;
        try {
            url = new MusicViewBD().download(id);
            System.out.println("<log> downloading " + prefix + url);
        }
        catch(Exception e) {
            throw new ServletException(e);
        }

        InputStream dis = null;
        OutputStream dos = null;

        File file = new File(prefix+url);
    	int filesize = (int)file.length();
        response.reset();
        response.setContentType("application/octet-stream; charset=UTF-8");
        response.addHeader("Content-Disposition", "attachment; filename="
            + java.net.URLEncoder.encode(file.getName(), "UTF-8"));
    	response.setContentLength(filesize);

        try {
            dis = new BufferedInputStream(new FileInputStream(file));
            dos = response.getOutputStream();
            byte[] buffer = new byte[4096];
            int n = 0;
            while((n=dis.read(buffer))!=(-1)) {
                dos.write(buffer, 0, n);
            }
            dis.close();
            dis = null;
            dos.close();
            dos = null;
            response.flushBuffer();
        }
        catch(IOException ioe) {
            System.out.println("-- download error: " + ioe.getMessage());
        }
        finally {
            if(dis!=null) dis.close();
            if(dos!=null) dos.close();
        }
    }

    public void doPost(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, java.io.IOException
    {
        throw new ServletException("POST is not support.");
    }

}