Java Servlet简单实例分享(文件上传下载demo)

2024-02-21 19:22:04 310

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

packagecom.servletdemo;

importjava.io.IOException;
importjava.io.PrintWriter;

importjavax.servlet.ServletException;
importjavax.servlet.annotation.WebServlet;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;

/**
*ServletimplementationclassShowServlet
*/
@WebServlet("/ShowServlet")
publicclassShowServletextendsHttpServlet{
privatestaticfinallongserialVersionUID=1L;
PrintWriterpw=null;
/**
*@seeHttpServlet#HttpServlet()
*/
publicShowServlet(){
super();
//TODOAuto-generatedconstructorstub
}

/**
*@seeHttpServlet#doGet(HttpServletRequestrequest,HttpServletResponseresponse)
*/
protectedvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
//TODOAuto-generatedmethodstub
this.doPost(request,response);
}

/**
*@seeHttpServlet#doPost(HttpServletRequestrequest,HttpServletResponseresponse)
*/
protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
//TODOAuto-generatedmethodstub
request.setCharacterEncoding("gb2312");
response.setContentType("text/html;charset=gb2312");
pw=response.getWriter();
Stringname=request.getParameter("username");
Stringpassword=request.getParameter("password");
pw.println("username:"+name);
pw.println("
");
pw.println("userpassword:"+password);
}

}

input.jsp

<%@pagelanguage="java"contentType="text/html;charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>




servletdemo


/ShowServlet">


name



password

2.文件上传实例

UploadServlet.java

packagecom.servletdemo;

importjava.io.File;
importjava.io.FileOutputStream;
importjava.io.IOException;
importjava.io.InputStream;
importjava.io.OutputStream;
importjava.io.PrintWriter;
importjava.text.DateFormat;
importjava.util.Date;
importjava.util.List;
importjava.util.UUID;

importjavax.servlet.ServletException;
importjavax.servlet.annotation.WebServlet;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;

importorg.apache.commons.fileupload.FileItem;
importorg.apache.commons.fileupload.FileUploadException;
importorg.apache.commons.fileupload.ProgressListener;
importorg.apache.commons.fileupload.disk.DiskFileItemFactory;
importorg.apache.commons.fileupload.servlet.ServletFileUpload;
/**
*ServletimplementationclassUploadServlet
*/
@WebServlet("/servlet/UploadServlet")
publicclassUploadServletextendsHttpServlet{
privatestaticfinallongserialVersionUID=1L;

/**
*@seeHttpServlet#HttpServlet()
*/
publicUploadServlet(){
super();
//TODOAuto-generatedconstructorstub
}

/**
*@seeHttpServlet#doGet(HttpServletRequestrequest,HttpServletResponseresponse)
*/
protectedvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
//TODOAuto-generatedmethodstub
//设置编码
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriterpw=response.getWriter();
try{
//设置系统环境
DiskFileItemFactoryfactory=newDiskFileItemFactory();
//文件存储的路径
StringstorePath=getServletContext().getRealPath("/WEB-INF/files");
//判断传输方式formenctype=multipart/form-data
booleanisMultipart=ServletFileUpload.isMultipartContent(request);
if(!isMultipart)
{
pw.write("传输方式有错误！");
return;
}
ServletFileUploadupload=newServletFileUpload(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(newProgressListener(){

//pBytesRead：当前以读取到的字节数
//pContentLength：文件的长度
//pItems:第几项
publicvoidupdate(longpBytesRead,longpContentLength,
intpItems){
System.out.println("已读去文件字节:"+pBytesRead+"文件总长度："+pContentLength+"第"+pItems+"项");

}
});
//解析
Listitems=upload.parseRequest(request);
for(FileItemitem:items)
{
if(item.isFormField())//普通字段，表单提交过来的
{
Stringname=item.getFieldName();
Stringvalue=item.getString("UTF-8");
System.out.println(name+"=="+value);
}else
{
//StringmimeType=item.getContentType();获取上传文件类型
//if(mimeType.startsWith("image")){
InputStreamin=item.getInputStream();
StringfileName=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
StringnewStorePath=makeStorePath(storePath);
StringstoreFile=newStorePath+"\\"+fileName;
OutputStreamout=newFileOutputStream(storeFile);
byte[]b=newbyte[1024];
intlen=-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.FileSizeLimitExceededExceptione){
//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.SizeLimitExceededExceptione){
//总文件超出异常
pw.write("总文件不能超过6M");

}catch(FileUploadExceptione){
e.printStackTrace();
}
}

/**
*@seeHttpServlet#doPost(HttpServletRequestrequest,HttpServletResponseresponse)
*/
protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
//TODOAuto-generatedmethodstub
doGet(request,response);
}

privateStringmakeStorePath(StringstorePath){

Datedate=newDate();
DateFormatdf=DateFormat.getDateInstance(DateFormat.MEDIUM);
Strings=df.format(date);
Stringpath=storePath+"\\"+s;
Filefile=newFile(path);
if(!file.exists())
{
file.mkdirs();//创建多级目录，mkdir只创建一级目录
}
returnpath;

}
privateStringmakeStorePath2(StringstorePath,StringfileName){
inthashCode=fileName.hashCode();
intdir1=hashCode&0xf;//0000~1111：整数0~15共16个
intdir2=(hashCode&0xf0)>>4;//0000~1111：整数0~15共16个

Stringpath=storePath+"\\"+dir1+"\\"+dir2;//WEB-INF/files/1/12
Filefile=newFile(path);
if(!file.exists())
file.mkdirs();

returnpath;
}

}

fileupload.jsp

<%@pagelanguage="java"contentType="text/html;charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>

<%
Stringpath=request.getContextPath();
StringbasePath=request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>





UploadFileDemo



username

3.文件下载实例

DownloadServlet.java

packagecom.servletdemo;

importjava.io.FileInputStream;
importjava.io.FileNotFoundException;
importjava.io.FileOutputStream;
importjava.io.IOException;
importjava.io.OutputStream;
importjava.io.PrintWriter;



importjava.net.URLEncoder;

importjavax.servlet.ServletException;
importjavax.servlet.annotation.WebServlet;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
importjavax.servlet.ServletResponse;

/**
*ServletimplementationclassDownloadServlet
*/
@WebServlet("/DownloadServlet")
publicclassDownloadServletextendsHttpServlet{
privatestaticfinallongserialVersionUID=1L;

/**
*@seeHttpServlet#HttpServlet()
*/
publicDownloadServlet(){
super();
//TODOAuto-generatedconstructorstub
}

/**
*@seeHttpServlet#doGet(HttpServletRequestrequest,HttpServletResponseresponse)
*/
protectedvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
//TODOAuto-generatedmethodstub
download1(response);
}

/**
*@seeHttpServlet#doPost(HttpServletRequestrequest,HttpServletResponseresponse)
*/
protectedvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{
//TODOAuto-generatedmethodstub
doGet(request,response);
}

publicvoiddownload1(HttpServletResponseresponse)throwsIOException{
//获取所要下载文件的路径
Stringpath=this.getServletContext().getRealPath("/files/web配置.xml");
StringrealPath=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
FileInputStreamfis=newFileInputStream(path);
intlen=0;
byte[]buf=newbyte[1024];
while((len=fis.read(buf))!=-1){
response.getOutputStream().write(buf,0,len);
}
}

}

download.html





DownloadDemo





download

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Java Servlet简单实例分享(文件上传下载demo)

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