Java Servlet简单实例分享(文件上传下载demo)
程序员文章站
2023-12-20 17:15:58
项目结构
src
com
servletdemo
downloadservlet.java
showservl...
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>
以上这篇java servlet简单实例分享(文件上传下载demo)就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。