import java.io.IOException;
import java.io.InputStream;

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

/**
 * 編碼下載
 */
public class DownloadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//獲取下載檔案的名稱
		String filename=request.getParameter("name");
		//上下文
		ServletContext context=getServletContext();
		//1.設定檔案的mimeType型別
		String mimeType=context.getMimeType(filename);
		response.setContentType(mimeType);
		//2.設定下載的頭資訊
		response.setHeader("content-disposition", "attachment;filename"+filename);
		//3.提供流
		//源
		InputStream is=context.getResourceAsStream("/download/"+filename);
		
		//目的
		ServletOutputStream sos=response.getOutputStream();
		int len=-1;
		byte[] buf=new byte[1024];
		while((len=is.read(buf))!=-1){
			sos.write(buf, 0, len);
			
		}
		sos.close();
		is.close();
	}

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

}