Servlet实现文件下载

最新推荐文章于 2024-09-17 17:10:15 发布

原创最新推荐文章于 2024-09-17 17:10:15 发布 · 342 阅读

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本文介绍了一个简单的Servlet实现，用于处理HTTP请求并提供文件下载功能。该实现通过读取指定路径的文件，并设置适当的HTTP响应头来触发浏览器的下载行为。

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package utils;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.StringReader;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Enumeration;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoadAndDown extends HttpServlet {
private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest req, HttpServletResponse res)
   throws ServletException, IOException {
  down(req,res);


}
protected void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
  //down(req,res);
  doGet(req,res);

}

public void down(HttpServletRequest req, HttpServletResponse res) throws IOException{
  String file=new String(req.getParameter("path").getBytes("ISO-8859-1"), "utf-8");//中文字符转码
  String path=getServletConfig().getServletContext().getRealPath(file);//取文件绝对路径
  //String name=path.substring(path.lastIndexOf("\\")+1);//取文件名
    File f=new File(path);
    long length=f.length();//取文件大小

    res.setContentLength((int)length);//下载文件时显示文件大小
    res.setHeader("content-disposition", "attachment;filename="+URLEncoder.encode(f.getName(),"utf-8"));
    if(f.isFile()){

     InputStream in=null;
        OutputStream out=null;
        try{
            in=new FileInputStream(f);
            int len;
            byte[] buffer=new byte[1024];

            out=res.getOutputStream();
            while((len=in.read(buffer))>0){
             out.write(buffer, 0, len);
            }
          }catch(Exception e){
          throw new RuntimeException(e);
          }finally{
          if(in!=null){in.close();}
          if(out!=null){out.close();}
          }
    }else{
     res.setContentType("text/html;charset=GBK");
     res.getWriter().print("指定文件不存在");
     return;
    }
}

}