package com.mingsoft.job.servlet;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.mingsoft.basic.servlet.BaseServlet;

@WebServlet(urlPatterns = "/downloadFile")
public class DownloadFileServlet  extends BaseServlet{

		/**
		 * 处理get请求下载文件
		 * @param request HttpServletRequest对象
		 * @param response HttpServletResponse 对象
		 * @throws ServletException Servlet异常处理
		 * @throws IOException IO异常处理
		 */
		@Override
		protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

			// 获取网站部署路径(通过ServletContext对象)，用于确定下载文件位置，从而实现下载
			String type = request.getParameter("type");
			String filePath = request.getParameter("file");
			filePath = "/upload/"+filePath;
			// 1.设置文件ContentType类型，这样设置，会自动判断下载文件类型
			response.setContentType("multipart/form-data");
			// 2.设置文件头：最后一个参数是设置下载文件名(假如我们叫a.pdf)
			response.setHeader("Content-Disposition", "attachment;fileName=" + request.getParameter("file"));
			ServletOutputStream out;
			// 通过文件路径获得File对象(假如此路径中有一个download.pdf文件)
			File file = new File(this.getRealPath(request, filePath));

			try {
				FileInputStream inputStream = new FileInputStream(file);

				// 3.通过response获取ServletOutputStream对象(out)
				out = response.getOutputStream();

				int b = 0;
				byte[] buffer = new byte[512];
				while (b != -1) {
					b = inputStream.read(buffer);
					// 4.写到输出流(out)中
					out.write(buffer, 0, b);
				}
				inputStream.close();
				out.close();
				out.flush();
				
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

	}