文件的下载

文件的下载:

1). 步骤:

I. 设置 contentType 响应头: 设置响应的类型是什么 ? 通知浏览器是个下载的文件

response.setContentType("application/x-msdownload");

II. 设置 Content-Disposition 响应头: 通知浏览器不再有浏览器来自行处理(或打开)要下载的文件, 而由用户手工完成

response.setHeader("Content-Disposition", "attachment;filename=abc.txt");

III. 具体的文件: 可以调用 response.getOutputStream 的方式, 以 IO 流的方式发送给客户端.

OutputStream out = response.getOutputStream();
String pptFileName = "C:\Users\Think Pad\Desktop\__正在上课__\11.尚硅谷_JavaWEB_监听器.pptx";

InputStream in = new FileInputStream(pptFileName);

byte [] buffer = new byte[1024];
int len = 0;

while((len = in.read(buffer)) != -1){
out.write(buffer, 0, len);
}

in.close();

out不用关闭，是提供给用户的！

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;

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

/**
 * Servlet implementation class DownloadServlet
 */
public class DownloadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("application/x-msdownload"); 
        
        String fileName = "文件下载.pptx";
        response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));
        
        OutputStream out = response.getOutputStream();
        String pptFileName = "C:\Users\Think Pad\Desktop\__正在上课__\JavaWEB_监听器.pptx";
        
        InputStream in = new FileInputStream(pptFileName);
        
        byte [] buffer = new byte[1024];
        int len = 0;
        
        while((len = in.read(buffer)) != -1){
            out.write(buffer, 0, len);
        }
        
        in.close();
    }

}