如何在 Tomcat 7 中使用 Servlet 和 JSP 在 MySQL 数据库中插入图像
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时间：2020-08-31 13:12:08 来源:igfitidea点击:
How to insert image in MySQL database using Servlet and JSP in Tomcat 7
提问by Deepak Singh
I'm trying to insert an image in a MySQL database using Servlet and JSP in Tomcat 7. When I click on the save button, it displays null. I am not getting any errors.
我正在尝试在 Tomcat 7 中使用 Servlet 和 JSP 在 MySQL 数据库中插入图像。当我单击保存按钮时，它显示为空。我没有收到任何错误。
Also I set commons-fileupload.jarfile and commons-io.jarfile. If you have some demonstration code, please give me.
我还设置了commons-fileupload.jar文件和commons-io.jar文件。如果你有一些演示代码，请给我。
<%@ 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>File Upload to Database Demo</title>
</head>
<body>
<center>
<h1>File Upload to Database Demo</h1>
<form method="post" action="FileUploadDBServlet" enctype="multipart/form-data">
<table border="0">
<tr>
<td>First Name: </td>
<td><input type="text" name="firstName" size="50"/></td>
</tr>
<tr>
<td>Last Name: </td>
<td><input type="text" name="lastName" size="50"/></td>
</tr>
<tr>
<td>Portrait Photo: </td>
<td><input type="file" name="photo" size="50"/></td>
</tr>
<tr>
<td colspan="2">
<input type="submit" value="Save">
</td>
</tr>
</table
</form>
</center>
</body>
</html>
FileUploadDBServlet.java:
文件上传DBServlet.java:
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import 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("/FileUploadDBServlet")
@MultipartConfig(maxFileSize = 16177215) // upload file's size up to 16MB
public class FileUploadDBServlet extends HttpServlet {
// database connection settings
private String dbURL = "jdbc:mysql://localhost:3306/AppDB";
private String dbUser = "root";
private String dbPass = "root";
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// gets values of text fields
String firstName = request.getParameter("firstName");
String lastName = request.getParameter("lastName");
InputStream inputStream = null; // input stream of the upload file
// obtains the upload file part in this multipart request
Part filePart = request.getPart("photo");
if (filePart != null) {
// prints out some information for debugging
System.out.println(filePart.getName());
System.out.println(filePart.getSize());
System.out.println(filePart.getContentType());
// obtains input stream of the upload file
inputStream = filePart.getInputStream();
}
Connection conn = null; // connection to the database
String message = null; // message will be sent back to client
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection(dbURL,dbUser,dbPass);
String sql =("INSERT INTO contacts (first_name, last_name, photo) values (?, ?, ?)");
PreparedStatement statement = conn.prepareStatement(sql);
statement.setString(1, firstName);
statement.setString(2, lastName);
if (inputStream != null) {
// fetches input stream of the upload file for the blob column
statement.setBlob(3, inputStream);
}
// sends the statement to the database server
int row = statement.executeUpdate();
if (row > 0) {
message = "File uploaded and saved into database";
}
} catch (Exception ex) {
message = "ERROR: " + ex.getMessage();
ex.printStackTrace();
} finally {
if (conn != null) {
// closes the database connection
try {
conn.close();
} catch (SQLException ex) {
ex.printStackTrace();
}
}
// sets the message in request scope
request.setAttribute("Message", message);
// forwards to the message page
getServletContext().getRequestDispatcher("/Message.jsp").forward(request, response);
}
}
}
web.xml:
网页.xml:
<web-app>
<servlet>
<servlet-name>FileUploadDBServlet</servlet-name>
<servlet-class>FileUploadDBServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>FileUploadDBServlet</servlet-name>
<url-pattern>/FileUploadDBServlet</url-pattern>
</servlet-mapping>
</web-app>
回答by Arunkumar Papena
The following code explains how to store/retrieve an image to/from db.
以下代码解释了如何在 db 中存储/检索图像。
First create a table in your db using following code
首先使用以下代码在您的数据库中创建一个表
CREATE TABLE contacts (
contact_id int PRIMARY KEY AUTO_INCREMENT,
first_name varchar(45) DEFAULT NULL,
last_name varchar(45) DEFAULT NULL,
photo` mediumblob);
Create a jsp file for input parameters.
为输入参数创建一个jsp文件。
Upload.jsp:
上传.jsp：
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>File Upload to Database</title>
</head>
<body>
<h1>File Upload to Database</h1>
<form name="fileform" method="post" action="uploadServlet" enctype="multipart/form-data">
<label for="firstName">First Name:</label>
<input type="text" name="firstName" size="50" placeholder="Enter Your FirstName" required/><br><br>
<label for="lastName">Last Name: </label>
<input type="text" name="lastName" size="50" placeholder="Enter Your LastName" required/><br><br>
<label for="photo"> Portrait Photo: </label>
<input type="file" name="photo" size="50" placeholder="Upload Your Image" required/><br><br>
<input type="submit" value="Save">
</form>
</body>
</html>
Next create controller for uploading image. In this case, I'm using a servlet.
接下来创建用于上传图像的控制器。在本例中，我使用的是 servlet。
FileUploadDbServlet.java:
FileUploadDbServlet.java：
package com.fileupload.attach;
import java.io.IOException;
import java.io.InputStream;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.ResultSet;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
@MultipartConfig(maxFileSize = 16177215)
// upload file's size up to 16MB
public class FileUploadDBServlet extends HttpServlet {
private static final int BUFFER_SIZE = 4096;
// database connection settings
private String dbURL = "jdbc:mysql://localhost:3306/mysql";
private String dbUser = "root";
private String dbPass = "arun";
//naive way to obtain a connection to database
//this MUST be improved, shown for
private Connection getConnection() {
Connection conn = null;
try {
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
conn = DriverManager.getConnection(dbURL, dbUser, dbPass);
} catch (Exception e) {
//wrapping any exception and rethrowing it
//inside a RuntimeException
//so the method is silent to exceptions
throw new RuntimeException("Failed to obtain database connection.", e);
}
return conn;
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//get values of text fields
String firstName = request.getParameter("firstName");
String lastName = request.getParameter("lastName");
InputStream inputStream = null; // input stream of the upload file
// obtains the upload file part in this multipart request
Part filePart = request.getPart("photo");
if (filePart != null) {
// prints out some information for debugging
System.out.println(filePart.getName());
System.out.println(filePart.getSize());
System.out.println(filePart.getContentType());
//obtains input stream of the upload file
//the InputStream will point to a stream that contains
//the contents of the file
inputStream = filePart.getInputStream();
}
Connection conn = null; // connection to the database
String message = null; // message will be sent back to client
try {
// connects to the database
conn = getConnection();
// constructs SQL statement
String sql = "INSERT INTO contacts (first_name, last_name, photo) values (?, ?, ?)";
//Using a PreparedStatement to save the file
PreparedStatement pstmtSave = conn.prepareStatement(sql);
pstmtSave.setString(1, firstName);
pstmtSave.setString(2, lastName);
if (inputStream != null) {
//files are treated as BLOB objects in database
//here we're letting the JDBC driver
//create a blob object based on the
//input stream that contains the data of the file
pstmtSave.setBlob(3, inputStream);
}
//sends the statement to the database server
int row = pstmtSave.executeUpdate();
if (row > 0) {
message = "File uploaded and saved into database";
}
String filepath = "D:/Dev/JavaWorkSpaceNew/FileUploadDatabase/WebContent/FromDb.jpg";
//Obtaining the file from database
//Using a second statement
String sql1 = "SELECT photo FROM contacts WHERE first_name=? AND last_name=?";
PreparedStatement pstmtSelect = conn.prepareStatement(sql1);
pstmtSelect.setString(1, firstName);
pstmtSelect.setString(2, lastName);
ResultSet result = pstmtSelect.executeQuery();
if (result.next()) {
Blob blob = result.getBlob("photo");
InputStream inputStream1 = blob.getBinaryStream();
OutputStream outputStream = new FileOutputStream(filepath);
int bytesRead = -1;
byte[] buffer = new byte[BUFFER_SIZE];
while ((bytesRead = inputStream1.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
inputStream1.close();
outputStream.close();
System.out.println("File saved");
}
} catch (SQLException ex) {
message = "ERROR: " + ex.getMessage();
ex.printStackTrace();
} finally {
if (conn != null) {
// closes the database connection
try {
conn.close();
} catch (SQLException ex) {
//silent
}
}
// sets the message in request scope
request.setAttribute("message", message);
// forwards to the message page
getServletContext().getRequestDispatcher("/Message.jsp")
.include(request, response);
}
}
}
web.xml:
网页.xml：
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<display-name>servletFileUpload</display-name>
<welcome-file-list>
<welcome-file>Upload.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description></description>
<display-name>FileUploadDBServlet</display-name>
<servlet-name>FileUploadDBServlet</servlet-name>
<servlet-class>com.fileupload.attach.FileUploadDBServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>FileUploadDBServlet</servlet-name>
<url-pattern>/uploadServlet</url-pattern>
</servlet-mapping>
</web-app>
Message.jsp:
消息.jsp：
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Message</title>
</head>
<body>
<h3>Result of the operation: ${message}</h3>
</body>
</html>
回答by RAHUL CHAURASIA
Jsp Page
Save this page with any name
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<form action="abc" method="post" enctype="multipart/form-data"> <br><br>
<table>
<tr>
<td>UserName: </td>
<td width='10px'></td>
<td><input type="text" name="name"/></td>
</tr>
<tr>
<td>Upload: </td>
<td width='10px'></td>
<td><input type="file" name="file" value="Upload"/></td>
</tr>
<tr>
<td><input type="submit" value="submit"></td>
</tr>
</table>
</form>
</body>
</html>
Servlet page and save this page as abc.java
source code
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import 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(urlPatterns = {"/abc"})
@MultipartConfig(fileSizeThreshold = 1024 * 1024 * 10, maxFileSize = 1024 * 1024 * 50, maxRequestSize = 1024 * 1024 * 100)
public class abc extends HttpServlet {
// this if directory name where the file will be uploaded and saved
private static final String SAVE_DIR = "images";
// this is the method which is created by system it self
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
try (PrintWriter out = response.getWriter()) {
// this tyr is created by me for the connection of database
try {
// this is the path provide by me to save the image
String savePath = "C:" + File.separator + SAVE_DIR;
/*in place of C: you can place a path wher you need to save the image*/
// this comment will picup the image file and have convert it into file type
File fileSaveDir = new File(savePath);
if (!fileSaveDir.exists()) {
fileSaveDir.mkdir();
}
// this two comment will take the name and image form web page
String name = request.getParameter("name");
Part part = request.getPart("file");
// this comment will extract the file name of image
String fileName = extractFileName(part);
// this will print the image name and user provide name
out.println(fileName);
out.println("\n" + name);
/*if you may have more than one files with same name then you can calculate
some random characters and append that characters in fileName so that it will
make your each image name identical.*/
part.write(savePath + File.separator + fileName);
/*
You need this loop if you submitted more than one file
for (Part part : request.getParts()) {
String fileName = extractFileName(part);
part.write(savePath + File.separator + fileName);
}*/
// connectio to database
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("url", "host -name", "password");
// query to insert name and image name
String query = "INSERT INTO image_link (name,photourl) values (?, ?)";
PreparedStatement pst;
pst = con.prepareStatement(query);
pst.setString(1, name);
String filePath = savePath + File.separator + fileName;
pst.setString(2, filePath);
pst.executeUpdate();
} catch (Exception ex) {
out.println("error" + ex);
}
}
}
// the extractFileName() is method used to extract the file name
private String extractFileName(Part part) {
String contentDisp = part.getHeader("content-disposition");
String[] items = contentDisp.split(";");
for (String s : items) {
if (s.trim().startsWith("filename")) {
return s.substring(s.indexOf("=") + 2, s.length() - 1);
}
}
return "";
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
@Override
public String getServletInfo() {
return "Short description";
}// </editor-fold>
}
