servlet下载文件实现代码详解（五）

servlet下载文件实现代码详解（五）

本文实例为大家分享了servlet下载文件的具体代码，供大家参考，具体内容如下

1.servlet下载文件

servlet下载文件就是将服务器端的文件传输到客户端。

2案例

下载文件servlet类

package com.learn;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

/**

* Created by Administrator on 2017/09/24.

*/

public class DownLoadServlet extends HttpServlet {

private String filePath;

@Override

public void init(ServletConfig config) throws ServletException {

super.init(config);

filePath = config.getInitParameter("filePath");

//初始化路径

//filePath = config.getServletContext().getRealPath(filePath);

System.out.println("初始化文件路径："+filePath);

}

@Override

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

doPost(req,resp);

}

@Override

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

OutputStream out; //输出流

InputStream in; //输入流

String fileName = req.getParameter("fileName");

System.out.println("文件名称："+fileName);

//如果把文件名为null则提示用户

if(fileName == null){

out = resp.getOutputStream();

out.write("please input fileName".getBytes());

out.close();

}

//获取文件流

in = getServletContext().getResourceAsStream(filePath+ File.separator+fileName);

System.out.println(in==null?true:false);

int length = in.available();

//设置返回消息头部信息

resp.setContentType("application/force-download");

resp.setHeader("Content-Length",String.valueOf(length));

http:// resp.setHeader("content-disposition","attachment;filename=\""+fileName+"\"");

//输出文件到客户端

out = resp.getOutputStream();

int bytesend = 0 ;

byte[] buff = new byte[512];

while ((bytesend = in.read(buff))!= -1){

out.write(buff,0,bytesend);

}

in.close();

out.close();

}

}

web.xml配置

download

com.learn.DownLoadServlet

filePath

file

&lthttp://;servlet-name>download

/download

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