Java Servlet简单实例分享(文件上传下载demo)
作者：jingxian 发布时间：2022-03-03 06:35:04
标签：java,文件,上传,下载
项目结构
src
com
servletdemo
DownloadServlet.java
ShowServlet.java
UploadServlet.java
WebContent
jsp
servlet
download.html
fileupload.jsp
input.jsp
WEB-INF
lib
commons-fileupload-1.3.1.jar
commons-io-2.4.jar
1.简单实例
ShowServlet.java
package com.servletdemo;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class ShowServlet
*/
@WebServlet("/ShowServlet")
public class ShowServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
PrintWriter pw=null;
/**
* @see HttpServlet#HttpServlet()
*/
public ShowServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
this.doPost(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
request.setCharacterEncoding("gb2312");
response.setContentType("text/html;charset=gb2312");
pw=response.getWriter();
String name=request.getParameter("username");
String password=request.getParameter("password");
pw.println("user name:" + name);
pw.println("<br>");
pw.println("user password:" + password);
}
}
input.jsp
<％@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"％>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>servlet demo</title>
</head>
<body>
<form action="<％=request.getContextPath()％>/ShowServlet">
<table>
<tr>
<td>name</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>password</td>
<td><input type="text" name="password"></td>
</tr>
<tr>
<td><input type="submit" value="login"></td>
<td><input type="reset" value="cancel"></td>
</tr>
</table>
</form>
</body>
</html>
2.文件上传实例
UploadServlet.java
package com.servletdemo;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.text.DateFormat;
import java.util.Date;
import java.util.List;
import java.util.UUID;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.ProgressListener;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
/**
* Servlet implementation class UploadServlet
*/
@WebServlet("/servlet/UploadServlet")
public class UploadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public UploadServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//设置编码
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter pw = response.getWriter();
try {
//设置系统环境
DiskFileItemFactory factory = new DiskFileItemFactory();
//文件存储的路径
String storePath = getServletContext().getRealPath("/WEB-INF/files");
//判断传输方式 form enctype=multipart/form-data
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
if(!isMultipart)
{
pw.write("传输方式有错误！");
return;
}
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setFileSizeMax(4*1024*1024);//设置单个文件大小不能超过4M
upload.setSizeMax(4*1024*1024);//设置总文件上传大小不能超过6M
//监听上传进度
upload.setProgressListener(new ProgressListener() {
//pBytesRead：当前以读取到的字节数
//pContentLength：文件的长度
//pItems:第几项
public void update(long pBytesRead, long pContentLength,
int pItems) {
System.out.println("已读去文件字节 :"+pBytesRead+" 文件总长度："+pContentLength+" 第"+pItems+"项");
}
});
//解析
List<FileItem> items = upload.parseRequest(request);
for(FileItem item: items)
{
if(item.isFormField())//普通字段，表单提交过来的
{
String name = item.getFieldName();
String value = item.getString("UTF-8");
System.out.println(name+"=="+value);
}else
{
// String mimeType = item.getContentType(); 获取上传文件类型
// if(mimeType.startsWith("image")){
InputStream in =item.getInputStream();
String fileName = item.getName();
if(fileName==null || "".equals(fileName.trim()))
{
continue;
}
fileName = fileName.substring(fileName.lastIndexOf("\\")+1);
fileName = UUID.randomUUID()+"_"+fileName;
//按日期来建文件夹
String newStorePath = makeStorePath(storePath);
String storeFile = newStorePath+"\\"+fileName;
OutputStream out = new FileOutputStream(storeFile);
byte[] b = new byte[1024];
int len = -1;
while((len = in.read(b))!=-1)
{
out.write(b,0,len);
}
in.close();
out.close();
item.delete();//删除临时文件
}
}
// }
}catch(org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException e){
//单个文件超出异常
pw.write("单个文件不能超过4M");
}catch(org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException e){
//总文件超出异常
pw.write("总文件不能超过6M");
}catch (FileUploadException e) {
e.printStackTrace();
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
private String makeStorePath(String storePath) {
Date date = new Date();
DateFormat df = DateFormat.getDateInstance(DateFormat.MEDIUM);
String s = df.format(date);
String path = storePath+"\\"+s;
File file = new File(path);
if(!file.exists())
{
file.mkdirs();//创建多级目录，mkdir只创建一级目录
}
return path;
}
private String makeStorePath2(String storePath, String fileName) {
int hashCode = fileName.hashCode();
int dir1 = hashCode & 0xf;// 0000~1111：整数0~15共16个
int dir2 = (hashCode & 0xf0) >> 4;// 0000~1111：整数0~15共16个
String path = storePath + "\\" + dir1 + "\\" + dir2; // WEB-INF/files/1/12
File file = new File(path);
if (!file.exists())
file.mkdirs();
return path;
}
}
fileupload.jsp
<％@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"％>
<％
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
％>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Upload File Demo</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/servlet/UploadServlet" method="post" enctype="multipart/form-data">
user name<input type="text" name="username"/> <br/>
<input type="file" name="f1"/><br/>
<input type="file" name="f2"/><br/>
<input type="submit" value="save"/>
</form>
</body>
</html>
3.文件下载实例
DownloadServlet.java
package com.servletdemo;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletResponse;
/**
* Servlet implementation class DownloadServlet
*/
@WebServlet("/DownloadServlet")
public class DownloadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public DownloadServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
download1(response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
public void download1(HttpServletResponse response) throws IOException{
//获取所要下载文件的路径
String path = this.getServletContext().getRealPath("/files/web配置.xml");
String realPath = path.substring(path.lastIndexOf("\\")+1);
//告诉浏览器是以下载的方法获取到资源
//告诉浏览器以此种编码来解析URLEncoder.encode(realPath, "utf-8"))
response.setHeader("content-disposition","attachment; filename="+URLEncoder.encode(realPath, "utf-8"));
//获取到所下载的资源
FileInputStream fis = new FileInputStream(path);
int len = 0;
byte [] buf = new byte[1024];
while((len=fis.read(buf))!=-1){
response.getOutputStream().write(buf,0,len);
}
}
}
download.html
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Download Demo</title>
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body>
<a href = "/JavabeanDemo/DownloadServlet">download</a>
</body>
</html>
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