Java代码实现文件下载
昨天晚上写了一篇文件上传的，今天上午把文件下载弄了一下，还是commons中的包
commons-fileupload.jar、commons-io.jar,下载位置就不说了,apache网站上找
这是一个web工程,下面有个截图
仅供参考,下面是index.jsp代码
View Code
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
response.sendRedirect("showfile.jspx");
%>
showfile.jsp
View Code
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>文件下载</title>
</head>
<body>
请选择您要下载的文件：<br/>
<c:forEach items="${fileList}" var="fileName">
<a href="download.jspx?filename=${fileName }">${fileName }</a><br/>
</c:forEach>
</body>
</html>
web.xml,这个没什么好看的,大家新建servlet时会自动完成web.xml中内容,其实就是请求servlet路径
View Code
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<display-name></display-name>
<servlet>
<servlet-name>ShowFileServlet</servlet-name>
<servlet-class>ShowFileServlet</servlet-class>
</servlet>
<servlet>
<servlet-name>DownLoadServlet</servlet-name>
<servlet-class>DownLoadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ShowFileServlet</servlet-name>
<url-pattern>/showfile.jspx</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>DownLoadServlet</servlet-name>
<url-pattern>/download.jspx</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
好了,下面是servlet了
ShowFileServlet.java
View Code
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ShowFileServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String path="D:/file";//下载资源位置
List<String> fileList = new ArrayList<String>();//声明集合存放目录下所有文件的文件名
File folder = new File(path);
//判断文件夹是否存在并且是否是一个目录
if(folder.exists()&&folder.isDirectory()){
//获得目录中所有文件及目录
File[] files = folder.listFiles();
for(File file:files){
//如果是文件
if(file.isFile()){
//将文件名放入集合
fileList.add(file.getName());
}
}
}
request.setAttribute("fileList", fileList);
request.getRequestDispatcher("showfile.jsp").forward(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
DownLoadServlet.java
View Code
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DownLoadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String path="D:/file";//资源位置
String fileName1 = request.getParameter("filename");
String fileName = new String(fileName1.getBytes("ISO-8859-1"),"utf-8");
File file = new File(path+"/"+fileName);//下载资源文件
//文件存在
if(file.exists()){
//设置响应类型及响应头
System.out.println(fileName);
response.setContentType("application/x-msdownload");
//防止输出文件名乱码以下两种均可
//response.setHeader( "Content-Disposition", "attachment;filename=\"" + new String( fileName.getBytes("gb2312"), "ISO8859-1" )+"\"");
response.addHeader("Content-Disposition", "attachment;filename=\""+URLEncoder.encode(fileName,"UTF-8")+"\"");
//读取文件
InputStream inputStream = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(inputStream);
byte[] bytes = new byte[1024];
ServletOutputStream outputStream = response.getOutputStream();//该对象可以在响应中写入二进制数据
BufferedOutputStream bos = new BufferedOutputStream(outputStream);
int readLength = 0;
while((readLength = bis.read(bytes))!=-1){
bos.write(bytes,0,readLength);
}
//释放资源
inputStream.close();
bis.close();
bos.flush();
outputStream.close();
bos.flush();
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
好了，还有一点要注意，就是资源位置，我这里是在D盘创建了一个file文件夹，里面存存放几个测试文件就好了
