How To Resolve The Installation Requirements For Windows XP SP3
February 26, 2022
If you have determined that you need to install Windows XP Service Pack 3, the following instructions will help you.
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This tutorial shows how Java implements a WWW application (using a servlet and a JSP) that specifically uploads files to the server and pulls files from the database. Content:
- Create MySQL database table
- Encode form boost page
- Encode file upload servlet
- Encode notification page < /li>
- Test each of our applications and check the files stored in the database
- Servlet 3.0+: Starting with Servlet 3.0, we can usually write code that handles image loading very well. For more information, see this important tutorial: Using a Servlet to Download Java Files. The code works with the latest version of the servlet API (servlet 4.0 or 4.1)
- MySQL 5.5 database or configuration: we store the uploaded files in a MySQL database. Read more about storing files in a MySQL database in this article.
- Upload.jsp: is a special form that allows users to enter some information (name and old name) and upload a file (portrait).
- FileUploadDBServlet: Captures input from any upload form, stores the upload content in the database, and redirects the browser to the message page.
- Message.jsp: Always displays a success or error message.
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Now let’s take a closer look at each part of the task.
1. Create A MySQL Database Table
First we create a data source and a table in MySQL. Run the following script using the MySQL command line client or MySQL Workbench:
Create AppDB database;Use AppDB;CREATE TABLE `Contacts` ( `contact_id` int(11) NOT NULL AUTO_INCREMENT, `firstname` varchar(45) DEFAULT NULL, `lastname` varchar(45) DEFAULT NULL, Medium "photo" blob, PRIMARY KEY (`contact_id`)) ENGINE=InnoDB default character set=latin1
The script creates a special database named AppDB and a desktop named Contacts. If the Photo column file is not used, it is considered a Medium Blob and can store up to 16 MB of binary data. For large files, use longblob (up to 4 GB).
2. Download Form Page Code
<%@language="java" contentType="text/html; charset=ISO-8859-one"pageEncoding="ISO-8859-1"%>Uploading a file to the demo database Upload File To Demo Database
This web page displays two text fields (first and last name) and an application field that allows users to select a file to upload. The activity attribute of this form corresponds to uploadServlet, which is the URL of the servlet application that we will build in the next section.
3. Servlet For Downloading Encoding Files
package net.codejava.upload;import java.io.IOException;import java.io.InputStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.SQLException;importedis javax.servlet.ServletException;import javax.servlet.annotation.MultipartConfig;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.part;@WebServlet("/uploadServlet")@MultipartConfig (maxFileSize is 16177215) // Upload file size increased to 16MBThe public class FileUploadDBServlet extends HttpServlet// DB connection parametersprivate string dbURL = "jdbc:mysql://localhost:3306/AppDB";private String dbUser implies "root";private string dbPass = "secret";protected empty doPost(HttpServletRequest,HttpServletResponse) throws ServletException, IOException// Values are retrieved from text fieldsThe string firstName is request.getParameter("firstName");String lastName = request.getParameter("lastName");inputStream inputStream is null; // Input stream of the uploaded file// Get the part of the image loaded in this multipart requestThe part corresponds to filePart request.getPart("photo");if (file_part != null)// dump some info as debug infoSystem.out.println(filePart.getName());System.out.println(filePart.getSize());System.out.println(filePart.getContentType());// get the input stream from the increase fileinputStream = filePart.getInputStream();conn connection is empty; // ConnectRide to the baseString message means null; // message is sent to the clientTo attempt// to connect your databaseDriverManager.registerDriver(new com.mysql.jdbc.Driver());conn = DriverManager.getConnection(dbURL, dbUser, dbPass);// SQL create statementsql string equivalent to "INSERT IN Contacts (First Name, Last Name, Photo) Think (?,?,?)";The PreparedStatement statement means conn.prepareStatement(sql);Statement.setString(1, Name);operator.setString(2, LastName);if (input stream != null)// fetch input download stream declared for blob columnoperator.InputStream);// setblob(3, send instruction to database serverint row = instruction.executeUpdate();if (string > 0)message = "Additionally loaded file, saved in database";catch Ex) (sqExceptionMessage = "ERROR: " + ex.getMessage();ex.printStackTrace();minimumif (conn != null) Close// database connectionTo attemptclose connection();Find (SQLException ex)ex.printStackTrace();// Set up messaging within the requestrequest.setAttribute("message", message);// redirect this to the news pagegetServletContext().getRequestDispatcher("/Message.jsp").forward(request, response);- @WebServlet: mark my servlet to be loaded by the servlet panel on startup and simply Map it to the /uploadServlet schedule URL.
- @MultipartConfig: Specifies that this servlet handle can perform a multipart request. We limit the maximum file upload size to 16MB.
The doPost() method takes care of all the details. Three points stand out here:
- Getting a partial file element in a request:
Part filePart = request.getPart("photo");The name or company name of “Photos” can be found in the “File Experts” field on the Upload.jsp page.
- Get a stream of uploaded files:
< pre> inputStream is equal to filePart.getInputStream () ; - And pass the flow of expertise in the declaration:
Prepared statement.setBlob(3, inputStream);
If anyone wants to learn Java Servlet and JSP programming, I highly recommend reading this excellent book First Head Off Servlet and JSP.
4. Code News Page
Create a JSP description page named Message.jsp with the following code:
<%@page language="java" contentType="text/html; charset=ISO-8859-1" Page encoding="ISO-8859-1"%>Message <%=request.getAttribute("message")%>