Java uses the servlet implementation file to upload to the database and download files from the database __java

First, the front desk

1. Upload page

<%@ page language= "java" contenttype= "text/html; Charset=utf-8 "
    pageencoding=" UTF-8 "%>
<! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" "Http://www.w3.org/TR/html4/loose.dtd" >
2, download the principle of the page ditto

 
Second, upload


Package mainservlet;
Import Java.io.File;
Import Java.io.FileOutputStream;
Import java.io.IOException;
Import Java.io.InputStream;
Import Java.io.OutputStream;
Import Java.text.DateFormat;
Import Java.text.SimpleDateFormat;
Import Java.util.Calendar;
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.FileUploadBase;
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;
Import Bean.fliedao;
Import Bean.imgdao;
Import Bean.tb_flie;

Import bean.tb_img; /** * Servlet Implementation class upLoadhandleservlet */@WebServlet (name= "Uploadhandleservlet", urlpatterns= "/uploadhandleservlet") public class
	 Uploadhandleservlet extends HttpServlet {private static final long serialversionuid = 1L;
    Message prompts//private String massage= "";
        /** * @see httpservlet#httpservlet () * * * Public uploadhandleservlet () {super (); TODO auto-generated Constructor stub}/** * @see httpservlet#doget (httpservletrequest request, HTTPSERVLETRESP Onse response) */protected void doget (HttpServletRequest request, httpservletresponse response) throws Servletexceptio
		N, IOException {//The temporary files generated during upload are saved directory String Temppath=this.getservletcontext (). Getrealpath ("/web-inf/temp"); /** * The two ways to get the saved directory of uploaded files * Method 1 directory generation in the Tomcat directory, once Tomcat clears the project, this file disappears, not considered * 1, String Savepath = This.getservletcontext
		 (). Getrealpath ("/web-inf/upload"); * Method 2 Attfilepath bit webxml the path name configured inside, this directory is a fixed hard disk directory, will not disappear because the project is removed, stable and reliable * 2, String Savepath = This.getservletcontext (). Getinitparameter ("Attfilepath ");
		////Get the saved directory of uploaded files//string savepath = This.getservletcontext (). Getrealpath ("/web-inf/upload");
		Get the Save directory for uploaded files String savepath = This.getservletcontext (). Getinitparameter ("Attfilepath");
		File Tmpfile=new file (TempPath);
		If the temporary file does not exist, create a temporary directory e if (!tmpfile.exists ()) {Tmpfile.mkdir ();
        } String message = "";
		try{//Create a diskfileitemfactory factory diskfileitemfactory factory=new diskfileitemfactory ();
		Sets the size of the buffer to 100KB, if not specified, then the buffer size defaults to 10KB factory.setsizethreshold (1024*100);
		Set the Save directory for the temporary files generated when uploading factory.setrepository (tmpfile);
        Create a file upload parser servletfileupload upload = new Servletfileupload (factory);  Listening for file upload Progress Upload.setprogresslistener (new Progresslistener () {public void update long pbytesread, long
            pcontentlength, int arg2) {System.out.println ("File size: + Pcontentlength +", currently processed: "+ pbytesread);"
        
        }
        });
Set the maximum size of a single file to upload, which is currently set to 1024*1024 Byte, which is 1MB        Upload.setfilesizemax (1024*1024);
        Set the maximum number of uploaded files, maximum = The maximum size of multiple files uploaded at the same time, currently set to 10MB Upload.setsizemax (1024*1024*10); 4, using the Servletfileupload parser to parse the upload data, the result returned is a list<fileitem> set, each fileitem corresponding to a form of the input items List<fileitem
        > list = upload.parserequest (request); for (Fileitem item:list) {//If the data in Fileitem is encapsulated by a normal input item if (Item.isformfield ()) {Strin
                G name = Item.getfieldname ();
                Solve the Chinese garbled problem of the data of the normal input item String value = item.getstring ("UTF-8");
                Value = new String (value.getbytes ("iso8859-1"), "UTF-8");
            SYSTEM.OUT.PRINTLN (name + "=" + value);
                }else{//Get uploaded file name, String filename = Item.getname ();
                SYSTEM.OUT.PRINTLN (filename);
                if (Filename==null | | Filename.trim (). Equals ("")) {continue; //Resolve the Chinese garbled upload of the uploaded filename.Setheaderencoding ("UTF-8"); Note: Different browsers submit the file name is not the same, some browsers submit the file name is a path, such as: C:\a\b\1.txt, and some just simple file name, such as: 1.txt//Processing get the uploaded file filename of the path section, only retain the text
                Part filename = filename.substring (filename.lastindexof ("\") +1); /** * Save uploaded files to database * @author Baicai * Time upload * filen
    		    AME filename * Savepath File path * * */date Date=new date ();
    			DateFormat format=new SimpleDateFormat ("Yyyy-mm-dd hh:mm");
            	String Time=format.format (date);
            	Imgdao imgdao=new Imgdao ();
            	Tb_img tb_img=new tb_img (filename,savepath,time);
            	
                Imgdao.upimg (TB_IMG); Get upload file extension String fileextname = filename.substring (Filename.lastindexof (".")
                +1);
                If you need to limit the file type of upload, you can use the file extension to determine whether the file type uploaded is legitimate System.out.println ("uploaded file extension is:" +fileextname); Get iteThe input stream of the uploaded file in M is inputstream in = Item.getinputstream ();
                Get file saved name String savefilename = makefilename (filename);
                Get File Save directory String Realsavepath = Makepath (Savefilename, Savepath);
                Create a file output stream FileOutputStream out = new FileOutputStream (Realsavepath + "\" + savefilename);
                Create a buffer byte buffer[] = new byte[1024];
                Determine if the data in the input stream has been read out of the identity int len = 0;
                    The loop reads the input stream into the buffer, (len=in.read (buffer)) >0 indicates that there is also a data while (Len=in.read (buffer) >0) {
                Writes the data of the buffer to the specified directory (Savepath + "\" + filename) using the FileOutputStream output stream out.write (buffer, 0, Len);
                //Close the input stream in.close ();
                Turn off the output stream out.close ();
                Deletes the temporary files generated when processing file uploads//item.delete (); Response.getWriter (). println ("<script type= ' Text/javascript ' >alert" (' upload failed.
            ') </script> ");
	        A catch (Fileuploadbase.filesizelimitexceededexception e) {e.printstacktrace ()); Request.setattribute ("Message", "Single file exceeds maximum value ...")
	        ");
	        Request.getrequestdispatcher ("/message.jsp"). Forward (request, response);
	    Return
	        }catch (fileuploadbase.sizelimitexceededexception e) {e.printstacktrace (); Response.getwriter (). println ("<script type= ' Text/javascript ' >alert" (' The total size of the uploaded file exceeds the maximum value of the limit ...).
	        ') </script> ");
	    Return }catch (Exception e) {response.getwriter (). println (' <script type= ' text/javascript ' >alert ' (' upload failed.
	        ') </script> ");
	    E.printstacktrace (); }/** * @Method: Makefilename * @Description: Generate the file name of the uploaded file, the filename is: uuid+ "_" + the original name of the file * @param the original name of the filename file
* @return Uuid+ "_" + the original name of the file */private string Makefilename (string filename) {//2.jpg	        To prevent file overwrite, create a unique filename for uploading files return Uuid.randomuuid (). toString () + "_" + filename; /** * To prevent the occurrence of too many files under a directory, use the hash algorithm to break storage * @Method: Makepath * @Description: * * @param  filename filename, to generate storage directory based on filename * @param savepath file storage path * @return New storage directory/private string Makepath (string		 
	 		Filename,string Savepath) {//Calendar date=calendar.getinstance () with date to get filename; 
	 		SimpleDateFormat format1=new SimpleDateFormat ("Yyyy-mm-dd");
	 		String Name=format1.format (Date.gettime ());  String dir = savepath + "\" + name;
	 		Upload\2\3 upload\3\5 file File=new file (dir);
	        If the directory does not exist if (!file.exists ()) {///Create directory File.mkdirs ();
	    } return dir; /** * @see Httpservlet#dopost (httpservletrequest request, httpservletresponse response) * * protected void DoPost (H Ttpservletrequest request, HttpServletResponse response) throws Servletexception, Ioexception {//TODO auto-generated Method stub doget (request, response);
 }

}
 

Third, download

Package mainservlet;
Import Java.io.File;
Import Java.io.FileInputStream;
Import java.io.IOException;
Import Java.io.OutputStream;
Import Java.net.URLEncoder;
Import Java.text.SimpleDateFormat;

Import Java.util.Calendar;
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 Imgdown/@WebServlet (urlpatterns= "/imgdown", Name= "Imgdown") public class Imgdown ex
       
    Tends HttpServlet {private static final long serialversionuid = 1L;
        * * @see Httpservlet#httpservlet () * * * ()/public Imgdown () {super (); TODO auto-generated constructor stub} protected void Doget (HttpServletRequest request, HttpServletResponse Respo NSE) throws Servletexception, IOException {//get the filename to download String filename = request.getparameter ("Fliename")
        ; Filename = new String (filename.getbytes ("iso8859-1"), "UTF-8");
        Uploaded files are stored in subdirectories under the Attfilepath (d:/code) directory String Savepath = Request.getparameter ("Fliepath");
               Locate the file's directory by file name String Path = Findfilesavepathbyfilename (Filename,savepath);
        Get the file that you want to download = filename = new file (path + "\" + fileName);
        	If the file does not exist if (!file.exists ()) {request.setcharacterencoding ("utf-8"); Response.getwriter (). println ("<script type= ' text/javascript ' >alert (') The resources you are downloading are deleted.
        ') </script> ");
        //process filename String realname = filename.substring (Filename.indexof ("_") +1); Set the response header to control the browser to download the file Response.setheader ("Content-disposition", "attachment;filename=" + urlencoder.encode (realname,
        "UTF-8"));
        Read the file to be downloaded, save to the file input stream FileInputStream in = new FileInputStream (path + "\" + fileName);
        Create output stream OutputStream out = Response.getoutputstream (); Create buffer byte buffer[]= new byte[1024];
        int len = 0; Loops read the contents of the input stream into the buffer while (len=in.read (buffer) >0) {//output buffer contents to the browser to implement the file download Out.write (BU
        Ffer, 0, Len);
        //close file Input stream in.close ();
    Turn off the output stream out.close (); * * * @Method: Findfilesavepathbyfilename * @Description: File root directory by file name and storage to find the path to the file to download * @param file Name to download the filename * @param saverootpath upload file to save the root directory, that is, the/web-inf/upload directory * @return The storage directory of the files to download */public String Findfilesavepathbyfilename (String filename,string saverootpath) {//Calendar date=calendar.getinstance with date file name (		 
 		); 
 		SimpleDateFormat format1=new SimpleDateFormat ("Yyyy-mm-dd");
 		String Name=format1.format (Date.gettime ());
 		String dir = saverootpath + "\" + name;
 		File File=new file (dir);
        If the directory does not exist if (!file.exists ()) {///Create directory File.mkdirs ();
    } return dir; } public void DoPost (httpservletrequestRequest, HttpServletResponse response) throws Servletexception, IOException {doget (request, response)
    ; }
}
Database section
1. Entity


Package Bean;

public class Tb_img {
	private int id;
	Private String fliename;
	Private String Fliepath;
	private String date;
	public int getId () {return
		ID;
	}
	public void setId (int id) {
		this.id = ID;
	}
	Public String Getfliename () {return
		fliename;
	}
	public void Setfliename (String fliename) {
		this.fliename = fliename;
	}
	Public String Getfliepath () {return
		fliepath;
	}
	public void Setfliepath (String fliepath) {
		this.fliepath = Fliepath;
	}
	public void setdate (String date) {
		this.date = date;
	}
	Public String Getdat () {return
		date;
	}
	Public tb_img () {} public
	tb_img (int id,string fliename,string fliepath,string date) {
		this.id=id;
		This.fliename=fliename;
		This.fliepath=fliepath;
		this.date=date;
	}
	Public tb_img (String fliename,string fliepath,string date) {
		this.fliename=fliename;
		This.fliepath=fliepath;
		This.date=date
	}
}
 

2, Data layer

Package Bean;
Import java.sql.Connection;
Import java.sql.PreparedStatement;
Import Java.sql.ResultSet;
Import java.sql.SQLException;
Import java.util.ArrayList;

Import java.util.List;

Import Sqldb.sqldb;
	public class Imgdao {private Connection conn=sqldb.getconnection ();
	Tb_img Tb_img=null;
	List<tb_img> Tb_imgs=null; /** * Upload file picture */public void upimg (Tb_img tb_img) throws sqlexception{String sql= ' insert into IMG (Fliename,fliepa
		Th,date) VALUES (?,?,?) ";
		PreparedStatement ptmt=conn.preparestatement (SQL);
		Ptmt.setstring (1, Tb_img.getfliename ());
		Ptmt.setstring (2, Tb_img.getfliepath ());
		Ptmt.setstring (3, Tb_img.getdat ());
	Ptmt.executeupdate ();
		/** * Get ALL data */public list<tb_img> allimg () throws sqlexception{tb_imgs=new arraylist<> ();
		String sql= "SELECT * from IMG";
		PreparedStatement ptmt=conn.preparestatement (SQL);
		ResultSet Rs=ptmt.executequery ();
			while (Rs.next ()) {tb_img=new tb_img ();
	Tb_img.setid (Rs.getint ("id"));		Tb_img.setfliename (rs.getstring ("Fliename"));
			Tb_img.setfliepath (rs.getstring ("Fliepath"));
			Tb_img.setdate (rs.getstring ("date"));
		Tb_imgs.add (TB_IMG);
	return TB_IMGS; /** * Download View file */public list<tb_img> findimg (String context) throws sqlexception{Tb_imgs=new ARRAYLIST&L
		T;> (); String sql= "SELECT * from IMG where fliename like '%" +context + "% ' or fliepath like '%" +context + "% ' or id like '%" +contex
		T + "% '";
		PreparedStatement ptmt=conn.preparestatement (SQL);
		ResultSet Rs=ptmt.executequery ();
			while (Rs.next ()) {tb_img=new tb_img ();
			Tb_img.setid (Rs.getint ("id"));
			Tb_img.setfliename (rs.getstring ("Fliename"));
			Tb_img.setfliepath (rs.getstring ("Fliepath"));
		Tb_imgs.add (TB_IMG);
	return TB_IMGS;
 }
}
 

3. Linked Database

Package sqldb;
Import java.sql.Connection;
Import Java.sql.DriverManager;
Import java.sql.PreparedStatement;
Import Java.sql.ResultSet;

Import java.sql.SQLException;
	public class Sqldb {private static final String driver= "Com.microsoft.sqlserver.jdbc.SQLServerDriver";
	private static final String URL = "Jdbc:sqlserver://localhost:1433;databasename=text";
	private static final String user= "sa";
	 private static final String password= "123456"; /** * Get connection * @return/public static Connection getconnection () {try {Cl  
            Ass.forname (DRIVER);  
            Connection conn = drivermanager.getconnection (Url,user,password);  
        Return conn; 
        catch (SQLException e) {System.out.println (E.getmessage ());
        catch (ClassNotFoundException e) {System.out.println (E.getmessage ());  
    return null; * * * Close database connection, pay attention to the order of shutdown * * Public VOID Close (ResultSet RS, PreparedStatement PS, Connection conn) {if (rs!=null) {try{  
                Rs.close ();  
            Rs=null;  
            }catch (SQLException e) {e.printstacktrace ();  
                } if (ps!=null) {try{ps.close ();  
            Ps=null;  
            }catch (SQLException e) {e.printstacktrace ();  
                } if (conn!=null) {try{conn.close ();  
            Conn=null;  
            }catch (SQLException e) {e.printstacktrace (); 
 }  
        }  
    }  
}