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
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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));
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 download /download
