package gacl.response.study;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/*** @author gacl* 文件下载*/
public class ResponseDemo02 extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {downloadFileByOutputStream(response);//下载文件，通过OutputStream流
    }/*** 下载文件，通过OutputStream流* @param response* @throws FileNotFoundException* @throws IOException*/private void downloadFileByOutputStream(HttpServletResponse response)throws FileNotFoundException, IOException {//1.获取要下载的文件的绝对路径String realPath = this.getServletContext().getRealPath("/download/1.JPG");//2.获取要下载的文件名String fileName = realPath.substring(realPath.lastIndexOf("\\")+1);//3.设置content-disposition响应头控制浏览器以下载的形式打开文件response.setHeader("content-disposition", "attachment;filename="+fileName);//4.获取要下载的文件输入流InputStream in = new FileInputStream(realPath);int len = 0;//5.创建数据缓冲区byte[] buffer = new byte[1024];//6.通过response对象获取OutputStream流OutputStream out = response.getOutputStream();//7.将FileInputStream流写入到buffer缓冲区while ((len = in.read(buffer)) > 0) {//8.使用OutputStream将缓冲区的数据输出到客户端浏览器out.write(buffer,0,len);}in.close();}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}
}