I had a problem in my servlet regarding deleting record from my database.
Please look over my servlet code and please do correct me. Thank you in advance
DeleteRow servlet is working perfectly right when a single ID is given manually.
Scenario is:
ManageSinger.java servlet displays the records in database along with a "Delete" hyperLink in every row. But problem is whenever i try to press delete button.. it receives a null value for ID in deleterow.java servlet ..
Please guide me from here how can only that corresponding ID can be pass to another servlet.
ManageSinger.java
package com.ea.servlet;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class ManageSinger extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException {
PrintWriter out = res.getWriter();
res.setContentType("text/html");
out.println("<html><body>");
try {
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/EATWO","root","");
Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select * from singerdetails");
out.println("<form method = \"post\">");
out.println("<table border=1 width=50% height=50%>");
out.println("<tr><th align=\"center\">Singer Name</th><th align=\"center\">StageName</th><th align=\"center\">Language</th><th></th><tr>");
while (rs.next()) {
String singername = rs.getString("singername");
String stagename = rs.getString("stagename");
String language = rs.getString("language");
String id = rs.getString("userID");
HttpSession session = req.getSession(true);
session.setAttribute("userID",id);
out.println("<tr><td align=\"center\">" + singername + "</td><td align=\"center\">" + stagename + "</td><td align=\"center\">" + language + "</td><td align=\"center\">Delete</td></tr>");
}
out.println("</table>");
out.println("</form");
out.println("</body></html>");
con.close();
}
catch (Exception e) {
e.printStackTrace();
}finally{
}
}
}
DeleteRow.java
package com.ea.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.jws.Oneway;
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.http.HttpSession;
public class DeleteRow extends HttpServlet
{
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws IOException, ServletException
{
res.setContentType("text/html");
PrintWriter pw = res.getWriter();
Connection con;
PreparedStatement st;
ResultSet rs;
try
{
HttpSession session = req.getSession(true);
Class.forName("com.mysql.jdbc.Driver");
String id = (String) session.getAttribute("id");
System.out.println(id);
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/EATWO","root","");
st= con.prepareStatement("delete from singerdetails where userID = ?");
st.setString(1, id);
st.executeUpdate();
int i = st.executeUpdate();
if(i!=0)
pw.println("Deleting row...");
else if (i==0)
{
pw.println("<br>Row has been deleted successfully.");
}
}
catch(SQLException sx)
{
pw.println(sx);
}
catch(ClassNotFoundException cx)
{
pw.println(cx);
}
}
}
In DeleteRow.java say you should do String id = (String) session.getAttribute("userID"); instead of (String) session.getAttribute("id") .In ManageSinger.java you are setting the attribute as follows session.setAttribute("userID",id);
As per your current ManageSinger.java only the last userID gets set in session, which is why the last userID gets deleted. In ManageSinger.java instead of setting the userID as session attribute you can set it as url parameter for each record.
Following lists the changes:
//HttpSession session = req.getSession(true);
//session.setAttribute("userID",id);
out.println("<tr><td align=\"center\">" + singername + "</td><td align=\"center\">" + stagename + "</td><td align=\"center\">" + language + "</td><td align=\"center\">Delete</td></tr>");
In DeleteRow.java instead of getting the userID from session, you can get it from the url as following:
//HttpSession session = req.getSession(true);
//String id = (String) session.getAttribute("id");
String id = req.getParameter("userID").toString();
Related
Working on a project where I am trying to allow a user to enter an ISBN on the client (LibrarySystem), and when the button searchARL is pressed, it sends the ISBN to the server (ARLibrary). If the ISBN is present in the ARLibrary, it tells the client its available. If it doesn't exist in the ARLibrary database, it tells the client that the ISBN does not exist.
My problem is that I cannot seem to establish a connection between my server/client. I really have no idea what I am doing wrong but any help would be appreciated.
UPDATE: It seems like I DID get them to connect, but on line 164:
String resultFromARLibrary = (String) inputStream.readObject();
I am getting an exception that states:
Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
How do I go about fixing this?
Server code:
import java.net.ServerSocket;
import java.net.Socket;
import java.net.InetAddress;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.IOException;
import javax.swing.JOptionPane;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.ResultSet;
public class ARLibraryServer{
private ServerSocket serverSocket;
private Socket socket;
private ObjectInputStream inputStream;
private ObjectOutputStream outputStream;
private ResultSet result;
public ARLibraryServer(){
String URL = "jdbc:mysql://localhost/mulibrary?user=root&password=";
System.out.println("Server is running...");
try{
serverSocket = new ServerSocket(1098, 500);
while(true){
socket = serverSocket.accept();
inputStream = new ObjectInputStream(socket.getInputStream());
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection(URL);
int isbn = (int) inputStream.readObject();
socket = new Socket(InetAddress.getByName("localhost"), 1097);
outputStream = new ObjectOutputStream(socket.getOutputStream());
String messageMU = "ISBN: " + isbn +
"\nAvailable at Arlington Library";
Statement search_arlingtonrs = con.createStatement();
String sql_statement = "select title from book where isbn = "+isbn+"";
result = search_arlingtonrs.executeQuery(sql_statement);
int iffound = 0;
while(result.next()) {
iffound = 1;
System.out.println(result.getString(1));
outputStream.writeObject("ISBN: " +isbn+
"\nTitle: " + result.getString(1) +
"\nAvailable at Arlington Library");
outputStream.flush();
}
if (iffound == 0){
String notfound = "ISBN: " +isbn+ "is not available at Arlington Library.";
outputStream.flush();
}
}
}
catch(ClassNotFoundException e){e.printStackTrace();}
catch(SQLException e){e.printStackTrace();}
catch(IOException e){e.printStackTrace();}
}
public static void main(String [] args){
new ARLibraryServer();
}
}
Client Code:
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JButton;
import javax.swing.JTextField;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.JPanel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JOptionPane;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.ResultSet;
import java.net.Socket;
import java.net.InetAddress;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.io.ObjectInputStream;
//COMMANDS USED TO CREATE DATABASE:
//Applications/XAMPP/bin/mysql -u root
//show databases;
//create database mulibrary;
//use mulibrary;
//create table book (
//isbn char(9) primary key not null,
//title varchar(25));
public class LibrarySystem extends JFrame implements ActionListener{
private JLabel isbnLabel, titleLabel;
private JTextField isbnField, titleField;
private JButton addBook, searchMU, searchARL;
private JPanel centerPanel, centerPanel2, southPanel;
private ServerSocket serverSocket;
private Socket socket;
private ObjectInputStream inputStream;
private ObjectOutputStream outputStream;
private ResultSet result;
public LibrarySystem() {
isbnLabel = new JLabel("ISBN:");
titleLabel = new JLabel("Title:");
centerPanel = new JPanel();
centerPanel2 = new JPanel();
isbnField = new JTextField(15);
titleField = new JTextField(15);
centerPanel.add(isbnLabel);
centerPanel.add(isbnField);
centerPanel.add(titleLabel);
centerPanel.add(titleField);
centerPanel2.add(centerPanel);
centerPanel.setLayout(new GridLayout(2,2));
add(centerPanel2, BorderLayout.CENTER);
addBook = new JButton("Add New Book:");
addBook.addActionListener(this);
searchMU = new JButton("Search ISBN - MU Library");
searchMU.addActionListener(this);
searchARL = new JButton("Search ISBN - Arlington Library");
searchARL.addActionListener(this);
southPanel = new JPanel();
southPanel.add(addBook);
southPanel.add(searchMU);
southPanel.add(searchARL);
add(southPanel, BorderLayout.SOUTH);
setTitle("Library System");
setSize(600, 150);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent event) {
String URL = "jdbc:mysql://localhost/mulibrary?user=root&password=";
if(event.getSource()==addBook){
try{
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection(URL);
String isbnint = isbnField.getText();
int isbn = Integer.parseInt(isbnint);
String title = titleField.getText();
String output = "The following book has been added to the Marymount Library:" +
"\nISBN: " + isbn +
"\nTitle: " + title;
String insert_add = "insert into book (isbn, title) values ('"+isbn+"','"+title+"')";
Statement add = con.createStatement();
add.execute(insert_add);
System.out.println("Insert Successful.");
JOptionPane.showMessageDialog(null, output);
}
catch(ClassNotFoundException e){
e.printStackTrace();
}
catch(SQLException e){
e.printStackTrace();
}
}
else if(event.getSource()==searchMU){
try{
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection(URL);
String isbnint = isbnField.getText();
int isbn = Integer.parseInt(isbnint);
String title = titleField.getText();
Statement search_marymount = con.createStatement();
String sql_statement = "select title from book where isbn = "+isbn+"";
ResultSet result = search_marymount.executeQuery(sql_statement);
int lookfor = 0;
while(result.next()){
lookfor = 1;
System.out.println(result.getString(1));
JOptionPane.showMessageDialog(null, "ISBN: " + isbn + "\nTitle: " +
result.getString(1) + "\nAvailable at MU Library");
}
if(lookfor == 0){
String notfound = "ISBN: " + isbn + " is not available at MU Library.";
JOptionPane.showMessageDialog(null, notfound);
}
}
catch(ClassNotFoundException e){
e.printStackTrace();
}
catch(SQLException e){
e.printStackTrace();
}
}
else if(event.getSource()==searchARL){
try{
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection(URL);
String isbnint = isbnField.getText();
int isbn = Integer.parseInt(isbnint);
String title = titleField.getText();
serverSocket = new ServerSocket(1098, 500);
while(true){
socket = new Socket(InetAddress.getByName("localhost"), 1098);
outputStream = new ObjectOutputStream(socket.getOutputStream());
outputStream.writeObject(isbn);
outputStream.flush();
System.out.println("Message has been sent.");
socket = serverSocket.accept();
inputStream = new ObjectInputStream(socket.getInputStream());
String resultFromARLibrary = (String) inputStream.readObject();
JOptionPane.showMessageDialog(null, resultFromARLibrary);
}
}
catch(ClassNotFoundException e){
e.printStackTrace();
}
catch(SQLException e){
e.printStackTrace();
}
catch (IOException e){
e.printStackTrace();
}
}
}
public static void main(String [] args){
LibrarySystem app = new LibrarySystem();
}
}
An attempt you can try is to replace localhost with 127.0.0.1
Register.java
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
*
* #author srini
*/
#WebServlet(urlPatterns = {"/RegisterServlet"})
public class RegisterServlet extends HttpServlet {
/**
* Processes requests for both HTTP <code>GET</code> and <code>POST</code>
* methods.
*
* #param request servlet request
* #param response servlet response
* #throws ServletException if a servlet-specific error occurs
* #throws IOException if an I/O error occurs
*/
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws IOException,ServletException{
processRequset (request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequset (request,response);
}
#SuppressWarnings("unused")
public void processRequset(HttpServletRequest request,HttpServletResponse response)
throws IOException,ServletException{
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
String phone =request.getParameter("phone");
String username =request.getParameter("uname");
String password =request.getParameter("pass");
try{
Class.forName("com.mysql.jdbc.Driver");
Connection con=DriverManager.getConnection(
"jdbc:mysql://localhost:3306/register","root","toor");
PreparedStatement pstmt=con.prepareStatement("select * from headwy where unmae=? " );
ResultSet rs = pstmt.executeQuery();
if(rs.next()==true)
{
out.print("username already exist");
}
else {
String insertquery = "insert into headwwy (phone,uname,pass) values(?,?,?)";
pstmt.executeQuery("insertquery");
pstmt.setString(1,phone);
pstmt.setString(2,username);
pstmt.setString(3,password);
out.print("You are successfully registered...");
pstmt.close();
con.close();
}
}
catch (Exception e2) {System.out.println(e2);
}
out.close();
}
}
I am trying to check the existing data in database and insert the record.In the above try to execute it shows the blank page.
before insert command is worked but we adding the select command its not working.
using the select command for the check the database and in case any data existing the database it shows the record is already exist ,please choose the another name.
In case of no duplicate data not found,insert command perform the action and insert the new record into the database and it shows the new record in to database successfully.
But my code is not working for the properly.
thank you.
You have mistake in your code :
PreparedStatement pstmt=con.prepareStatement("select * from headwy where unmae=? " );
check your column name its "uname" not "unmae".
There are multiple issues in your code. First there is a typo. If that is the reason for failure.
select * from headwy where unmae=?
insert into headwwy (phone,uname,pass) values(?,?,?)
Also
pstmt.executeQuery("insertquery");
should be executed after you have set the parameters
pstmt.setString(1,phone);
pstmt.setString(2,username);
pstmt.setString(3,password);
I'll recommend to go through JDBC tutorial and run again.
You should set the parameters in your preparedstatement before executing your preparedstatement.
PreparedStatement pstmt=con.prepareStatement("select * from headwy where unmae=? " );
pstmt.setString(1,username);
ResultSet rs = pstmt.executeQuery();
if(rs.next())
{
System.out.print("username already exist");
}
How can I retrieve and display images from a database in a JSP page?
Let's see in steps what should happen:
JSP is basically a view technology which is supposed to generate HTML output.
To display an image in HTML, you need the HTML <img> element.
To let it locate an image, you need to specify its src attribute.
The src attribute needs to point to a valid http:// URL and thus not a local disk file system path file:// as that would never work when the server and client run at physically different machines.
The image URL needs to have the image identifier in either the request path (e.g. http://example.com/context/images/foo.png) or as request parameter (e.g. http://example.com/context/images?id=1).
In JSP/Servlet world, you can let a Servlet listen on a certain URL pattern like /images/*, so that you can just execute some Java code on specific URL's.
Images are binary data and are to be obtained as either a byte[] or InputStream from the DB, the JDBC API offers the ResultSet#getBytes() and ResultSet#getBinaryStream() for this, and JPA API offers #Lob for this.
In the Servlet you can just write this byte[] or InputStream to the OutputStream of the response the usual Java IO way.
The client side needs to be instructed that the data should be handled as an image, thus at least the Content-Type response header needs to be set as well. You can obtain the right one via ServletContext#getMimeType() based on image file extension which you can extend and/or override via <mime-mapping> in web.xml.
That should be it. It almost writes code itself. Let's start with HTML (in JSP):
<img src="${pageContext.request.contextPath}/images/foo.png">
<img src="${pageContext.request.contextPath}/images/bar.png">
<img src="${pageContext.request.contextPath}/images/baz.png">
You can if necessary also dynamically set src with EL while iterating using JSTL:
<c:forEach items="${imagenames}" var="imagename">
<img src="${pageContext.request.contextPath}/images/${imagename}">
</c:forEach>
Then define/create a servlet which listens on GET requests on URL pattern of /images/*, the below example uses plain vanilla JDBC for the job:
#WebServlet("/images/*")
public class ImageServlet extends HttpServlet {
// content=blob, name=varchar(255) UNIQUE.
private static final String SQL_FIND = "SELECT content FROM Image WHERE name = ?";
#Resource(name="jdbc/yourDB") // For Tomcat, define as <Resource> in context.xml and declare as <resource-ref> in web.xml.
private DataSource dataSource;
#Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String imageName = request.getPathInfo().substring(1); // Returns "foo.png".
try (Connection connection = dataSource.getConnection(); PreparedStatement statement = connection.prepareStatement(SQL_FIND)) {
statement.setString(1, imageName);
try (ResultSet resultSet = statement.executeQuery()) {
if (resultSet.next()) {
byte[] content = resultSet.getBytes("content");
response.setContentType(getServletContext().getMimeType(imageName));
response.setContentLength(content.length);
response.getOutputStream().write(content);
} else {
response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
}
}
} catch (SQLException e) {
throw new ServletException("Something failed at SQL/DB level.", e);
}
}
}
That's it. In case you worry about HEAD and caching headers and properly responding on those requests, use this abstract template for static resource servlet.
See also:
How should I connect to JDBC database / datasource in a servlet based application?
How to upload an image and save it in database?
Simplest way to serve static data from outside the application server in a Java web application
I suggest you address that as two problems. There are several questions and answer related to both.
How to load blob from MySQL
See for instance Retrieve image stored as blob
How to display image dynamically
See for instance Show thumbnail dynamically
I've written and configured the code in JSP using Oracle database.
Hope it will help.
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.http.HttpSession;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class displayfetchimage
*/
#WebServlet("/displayfetchimage")
public class displayfetchimage extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* #see HttpServlet#HttpServlet()
*/
public displayfetchimage() {
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
Statement stmt = null;
String sql = null;
BufferedInputStream bin = null;
BufferedOutputStream bout = null;
InputStream in = null;
response.setContentType("image/jpeg");
ServletOutputStream out;
out = response.getOutputStream();
Connection conn = employee.DbConnection.getDatabaseConnection();
HttpSession session = (HttpSession) request.getSession();
String ID = session.getAttribute("userId").toString().toLowerCase();
try {
stmt = conn.createStatement();
sql = "select user_image from employee_data WHERE username='" + ID + "' and rownum<=1";
ResultSet result = stmt.executeQuery(sql);
if (result.next()) {
in = result.getBinaryStream(1);// Since my data was in first column of table.
}
bin = new BufferedInputStream(in);
bout = new BufferedOutputStream(out);
int ch = 0;
while ((ch = bin.read()) != -1) {
bout.write(ch);
}
} catch (SQLException ex) {
Logger.getLogger(displayfetchimage.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
if (bin != null)
bin.close();
if (in != null)
in.close();
if (bout != null)
bout.close();
if (out != null)
out.close();
if (conn != null)
conn.close();
} catch (IOException | SQLException ex) {
System.out.println("Error : " + ex.getMessage());
}
}
}
// response.getWriter().append("Served at: ").append(request.getContextPath());
/**
* #see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Statement stmt = null;
String sql = null;
BufferedInputStream bin = null;
BufferedOutputStream bout = null;
InputStream in = null;
response.setContentType("image/jpeg");
ServletOutputStream out;
out = response.getOutputStream();
Connection conn = employee.DbConnection.getDatabaseConnection();
HttpSession session = (HttpSession) request.getSession();
String ID = session.getAttribute("userId").toString().toLowerCase();
try {
stmt = conn.createStatement();
sql = "select user_image from employee_data WHERE username='" + ID + "' and rownum<=1";
ResultSet result = stmt.executeQuery(sql);
if (result.next()) {
in = result.getBinaryStream(1);
}
bin = new BufferedInputStream(in);
bout = new BufferedOutputStream(out);
int ch = 0;
while ((ch = bin.read()) != -1) {
bout.write(ch);
}
} catch (SQLException ex) {
Logger.getLogger(displayfetchimage.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
if (bin != null)
bin.close();
if (in != null)
in.close();
if (bout != null)
bout.close();
if (out != null)
out.close();
if (conn != null)
conn.close();
} catch (IOException | SQLException ex) {
System.out.println("Error : " + ex.getMessage());
}
}
}
}
Try to flush and close the output stream if it does not display.
Blob image = rs.getBlob(ImageColName);
InputStream in = image.getBinaryStream();
// Output the blob to the HttpServletResponse
response.setContentType("image/jpeg");
BufferedOutputStream o = new BufferedOutputStream(response.getOutputStream());
byte by[] = new byte[32768];
int index = in.read(by, 0, 32768);
while (index != -1) {
o.write(by, 0, index);
index = in.read(by, 0, 32768);
}
o.flush();
o.close();
I used SQL SERVER database and so the answer's code is in accordance. All you have to do is include an <img> tag in your jsp page and call a servlet from its src attribute like this
<img width="200" height="180" src="DisplayImage?ID=1">
Here 1 is unique id of image in database and ID is a variable. We receive value of this variable in servlet. In servlet code we take the binary stream input from correct column in table. That is your image is stored in which column. In my code I used third column because my images are stored as binary data in third column. After retrieving input stream data from table we read its content in an output stream so it can be written on screen. Here is it
import java.io.*;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.*;
import javax.servlet.http.*;
import model.ConnectionManager;
public class DisplayImage extends HttpServlet {
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws IOException
{
Statement stmt=null;
String sql=null;
BufferedInputStream bin=null;
BufferedOutputStream bout=null;
InputStream in =null;
response.setContentType("image/jpeg");
ServletOutputStream out;
out = response.getOutputStream();
Connection conn = ConnectionManager.getConnection();
int ID = Integer.parseInt(request.getParameter("ID"));
try {
stmt = conn.createStatement();
sql = "SELECT * FROM IMAGETABLE WHERE ID="+ID+"";
ResultSet result = stmt.executeQuery(sql);
if(result.next()){
in=result.getBinaryStream(3);//Since my data was in third column of table.
}
bin = new BufferedInputStream(in);
bout = new BufferedOutputStream(out);
int ch=0;
while((ch=bin.read())!=-1)
{
bout.write(ch);
}
} catch (SQLException ex) {
Logger.getLogger(DisplayImage.class.getName()).log(Level.SEVERE, null, ex);
}finally{
try{
if(bin!=null)bin.close();
if(in!=null)in.close();
if(bout!=null)bout.close();
if(out!=null)out.close();
if(conn!=null)conn.close();
}catch(IOException | SQLException ex){
System.out.println("Error : "+ex.getMessage());
}
}
}
}
After the execution of your jsp or html file you will see the image on screen.
You can also create custom tag for displaying image.
1) create custom tag java class and tld file.
2) write logic to display image like conversion of byte[] to string by Base64.
so it is used for every image whether you are displaying only one image or multiple images in single jsp page.
This question already has an answer here:
jdbc to MYSQL error: No suitable driver found for jdbc:mysql://localhost:3306/test?user='root'&password='' [duplicate]
(1 answer)
Closed 7 years ago.
I've put mysql driver in .../ROOT/WEB-INF/lib and Tomcat 8.0/lib but it has no effect. I'm using the following class to connect to DB:
package db;
import java.sql.*;
public class ConnectToDB implements AutoCloseable {
Connection con;
public ConnectToDB(String server, String database, String user,
String password) throws SQLException {
con = DriverManager.getConnection("jdbc:mysql://" + server + "/"
+ database, user, password);
}
#Override
public void close() throws SQLException {
con.close();
}
public Connection getConnection() {
return con;
}
}
The following classes are included in the Eclipse project:
1. src/nr3/model
package nr3.model;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import db.ConnectToDB;
public class MusikkHandler {
private ConnectToDB db;
private Connection con;
private String tableName;
private PreparedStatement pstmtGetRows;
public MusikkHandler(String server, String database, String user,
String password) throws SQLException {
db = new ConnectToDB(server, database, user, password);
con = db.getConnection();
tableName = "album";
}
public void close() throws SQLException {
db.close();
}
public ArrayList<Album> getRows(String genre) throws SQLException {
ArrayList<Album> list = new ArrayList<Album>();
pstmtGetRows = con.prepareStatement("SELECT * FROM " + tableName
+ " WHERE SJANGER = ?");
pstmtGetRows.setString(1, genre);
ResultSet rs = pstmtGetRows.executeQuery();
while (rs.next()) {
list.add(new Album(rs.getString(1), rs.getString(2), rs.getInt(3),
rs.getInt(4), rs.getString(5)));
}
rs.close();
pstmtGetRows.close();
return list;
}
}
-
package nr3.model;
public class Album {
private String tittel;
private String artist;
private int spor;
private int utgitt;
private String sjanger;
public Album (String artist, String tittel, int spor, int utgitt, String sjanger){
setArtist(artist);
setTittel(tittel);
setUtgitt(utgitt);
setSpor(spor);
setSjanger(sjanger);
}
public Album(){
this(null, null, 0, 0, null);
}
public void setTittel(String tittel){
this.tittel = tittel;
}
public void setArtist(String artist){
this.artist = artist;
}
public void setSpor(int spor) {
this.spor = spor;
}
public void setUtgitt(int utgitt) {
this.utgitt = utgitt;
}
public void setSjanger(String sjanger) {
this.sjanger = sjanger;
}
public String getTittel() {
return tittel;
}
public String getArtist() {
return artist;
}
public int getSpor() {
return spor;
}
public int getUtgitt() {
return utgitt;
}
public String getSjanger() {
return sjanger;
}
public String toString(){
return getTittel() + " (" + getArtist() + ")" + " Utgitt: "
+ getUtgitt();
}
}
2. src/nr3/servlets
package nr3.servlets;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import nr3.model.Album;
import nr3.model.MusikkHandler;
public class MusikkValg extends HttpServlet {
private static final long serialVersionUID = 428937262021570370L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String genre = request.getParameter("sjanger");
response.setCharacterEncoding("UTF-8");
response.setContentType("text/html");
PrintWriter out = response.getWriter();
MusikkHandler mh;
out.println("<html>");
out.println("<head>");
out.println("<title>Musikk</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>MUSIKK-ANBEFALINGER</h1>");
out.println("<br/>");
out.println("<br/>");
out.println("<h3>Da bør du kanskje forsøke en av disse:</h3>");
out.println("<br/>");
out.println("<br/>");
try {
mh = new MusikkHandler(" ", " ", " ", " ");
for (Album a : mh.getRows(genre))
out.println("<p>" + a + "</p>");
} catch (SQLException e) {
e.printStackTrace(out);
}
out.println("</body>");
out.println("</html>");
}
}
Update: I've got the following error stacktrace in the browser:
java.sql.SQLException: No suitable driver found for
jdbc:mysql://localhost/pg3100 at
java.sql.DriverManager.getConnection(Unknown Source) at
java.sql.DriverManager.getConnection(Unknown Source) at
db.ConnectToDB.(ConnectToDB.java:10) at
nr3.model.MusikkHandler.(MusikkHandler.java:20) at
nr3.servlets.MusikkValg.doGet(MusikkValg.java:39) at
javax.servlet.http.HttpServlet.service(HttpServlet.java:618) at
javax.servlet.http.HttpServlet.service(HttpServlet.java:725) at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:534)
at
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1081)
at
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:658)
at
org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:277)
at
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2381)
at
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2370)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
First, you must register your driver at the beginning so DriverManager can user it when getting a connection. It might vary on the implementation.
DriverManager.registerDriver (new com.mysql.jdbc.Driver());
or
Class.forName("com.mysql.jdbc.Driver");
Then you can perform a getConnection() because you'll have a driver registered to be used by DriverManager.
Second: /webapps/ROOT/WEB-INF/lib is a different context and its libraries won't be available for your app unless you are setting the context path of your app as shown in this question. If you wanna add it, try placing your JDBC driver on /webapps/<yourapp>/lib first. Tomcat lib should work as well (but it's not nice when you distribute your app, might conflict with other apps deployed there, using different versions of the driver, etc.)
Third: When asking here, try to reduce your verifiable example to something readable. There's a lot of code which is not relevant to your problem. Reducing makes it easier to read your question and provide help.
How can I retrieve and display images from a database in a JSP page?
Let's see in steps what should happen:
JSP is basically a view technology which is supposed to generate HTML output.
To display an image in HTML, you need the HTML <img> element.
To let it locate an image, you need to specify its src attribute.
The src attribute needs to point to a valid http:// URL and thus not a local disk file system path file:// as that would never work when the server and client run at physically different machines.
The image URL needs to have the image identifier in either the request path (e.g. http://example.com/context/images/foo.png) or as request parameter (e.g. http://example.com/context/images?id=1).
In JSP/Servlet world, you can let a Servlet listen on a certain URL pattern like /images/*, so that you can just execute some Java code on specific URL's.
Images are binary data and are to be obtained as either a byte[] or InputStream from the DB, the JDBC API offers the ResultSet#getBytes() and ResultSet#getBinaryStream() for this, and JPA API offers #Lob for this.
In the Servlet you can just write this byte[] or InputStream to the OutputStream of the response the usual Java IO way.
The client side needs to be instructed that the data should be handled as an image, thus at least the Content-Type response header needs to be set as well. You can obtain the right one via ServletContext#getMimeType() based on image file extension which you can extend and/or override via <mime-mapping> in web.xml.
That should be it. It almost writes code itself. Let's start with HTML (in JSP):
<img src="${pageContext.request.contextPath}/images/foo.png">
<img src="${pageContext.request.contextPath}/images/bar.png">
<img src="${pageContext.request.contextPath}/images/baz.png">
You can if necessary also dynamically set src with EL while iterating using JSTL:
<c:forEach items="${imagenames}" var="imagename">
<img src="${pageContext.request.contextPath}/images/${imagename}">
</c:forEach>
Then define/create a servlet which listens on GET requests on URL pattern of /images/*, the below example uses plain vanilla JDBC for the job:
#WebServlet("/images/*")
public class ImageServlet extends HttpServlet {
// content=blob, name=varchar(255) UNIQUE.
private static final String SQL_FIND = "SELECT content FROM Image WHERE name = ?";
#Resource(name="jdbc/yourDB") // For Tomcat, define as <Resource> in context.xml and declare as <resource-ref> in web.xml.
private DataSource dataSource;
#Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String imageName = request.getPathInfo().substring(1); // Returns "foo.png".
try (Connection connection = dataSource.getConnection(); PreparedStatement statement = connection.prepareStatement(SQL_FIND)) {
statement.setString(1, imageName);
try (ResultSet resultSet = statement.executeQuery()) {
if (resultSet.next()) {
byte[] content = resultSet.getBytes("content");
response.setContentType(getServletContext().getMimeType(imageName));
response.setContentLength(content.length);
response.getOutputStream().write(content);
} else {
response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
}
}
} catch (SQLException e) {
throw new ServletException("Something failed at SQL/DB level.", e);
}
}
}
That's it. In case you worry about HEAD and caching headers and properly responding on those requests, use this abstract template for static resource servlet.
See also:
How should I connect to JDBC database / datasource in a servlet based application?
How to upload an image and save it in database?
Simplest way to serve static data from outside the application server in a Java web application
I suggest you address that as two problems. There are several questions and answer related to both.
How to load blob from MySQL
See for instance Retrieve image stored as blob
How to display image dynamically
See for instance Show thumbnail dynamically
I've written and configured the code in JSP using Oracle database.
Hope it will help.
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.http.HttpSession;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class displayfetchimage
*/
#WebServlet("/displayfetchimage")
public class displayfetchimage extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* #see HttpServlet#HttpServlet()
*/
public displayfetchimage() {
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
Statement stmt = null;
String sql = null;
BufferedInputStream bin = null;
BufferedOutputStream bout = null;
InputStream in = null;
response.setContentType("image/jpeg");
ServletOutputStream out;
out = response.getOutputStream();
Connection conn = employee.DbConnection.getDatabaseConnection();
HttpSession session = (HttpSession) request.getSession();
String ID = session.getAttribute("userId").toString().toLowerCase();
try {
stmt = conn.createStatement();
sql = "select user_image from employee_data WHERE username='" + ID + "' and rownum<=1";
ResultSet result = stmt.executeQuery(sql);
if (result.next()) {
in = result.getBinaryStream(1);// Since my data was in first column of table.
}
bin = new BufferedInputStream(in);
bout = new BufferedOutputStream(out);
int ch = 0;
while ((ch = bin.read()) != -1) {
bout.write(ch);
}
} catch (SQLException ex) {
Logger.getLogger(displayfetchimage.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
if (bin != null)
bin.close();
if (in != null)
in.close();
if (bout != null)
bout.close();
if (out != null)
out.close();
if (conn != null)
conn.close();
} catch (IOException | SQLException ex) {
System.out.println("Error : " + ex.getMessage());
}
}
}
// response.getWriter().append("Served at: ").append(request.getContextPath());
/**
* #see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Statement stmt = null;
String sql = null;
BufferedInputStream bin = null;
BufferedOutputStream bout = null;
InputStream in = null;
response.setContentType("image/jpeg");
ServletOutputStream out;
out = response.getOutputStream();
Connection conn = employee.DbConnection.getDatabaseConnection();
HttpSession session = (HttpSession) request.getSession();
String ID = session.getAttribute("userId").toString().toLowerCase();
try {
stmt = conn.createStatement();
sql = "select user_image from employee_data WHERE username='" + ID + "' and rownum<=1";
ResultSet result = stmt.executeQuery(sql);
if (result.next()) {
in = result.getBinaryStream(1);
}
bin = new BufferedInputStream(in);
bout = new BufferedOutputStream(out);
int ch = 0;
while ((ch = bin.read()) != -1) {
bout.write(ch);
}
} catch (SQLException ex) {
Logger.getLogger(displayfetchimage.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
if (bin != null)
bin.close();
if (in != null)
in.close();
if (bout != null)
bout.close();
if (out != null)
out.close();
if (conn != null)
conn.close();
} catch (IOException | SQLException ex) {
System.out.println("Error : " + ex.getMessage());
}
}
}
}
Try to flush and close the output stream if it does not display.
Blob image = rs.getBlob(ImageColName);
InputStream in = image.getBinaryStream();
// Output the blob to the HttpServletResponse
response.setContentType("image/jpeg");
BufferedOutputStream o = new BufferedOutputStream(response.getOutputStream());
byte by[] = new byte[32768];
int index = in.read(by, 0, 32768);
while (index != -1) {
o.write(by, 0, index);
index = in.read(by, 0, 32768);
}
o.flush();
o.close();
I used SQL SERVER database and so the answer's code is in accordance. All you have to do is include an <img> tag in your jsp page and call a servlet from its src attribute like this
<img width="200" height="180" src="DisplayImage?ID=1">
Here 1 is unique id of image in database and ID is a variable. We receive value of this variable in servlet. In servlet code we take the binary stream input from correct column in table. That is your image is stored in which column. In my code I used third column because my images are stored as binary data in third column. After retrieving input stream data from table we read its content in an output stream so it can be written on screen. Here is it
import java.io.*;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.*;
import javax.servlet.http.*;
import model.ConnectionManager;
public class DisplayImage extends HttpServlet {
public void doGet(HttpServletRequest request,HttpServletResponse response)
throws IOException
{
Statement stmt=null;
String sql=null;
BufferedInputStream bin=null;
BufferedOutputStream bout=null;
InputStream in =null;
response.setContentType("image/jpeg");
ServletOutputStream out;
out = response.getOutputStream();
Connection conn = ConnectionManager.getConnection();
int ID = Integer.parseInt(request.getParameter("ID"));
try {
stmt = conn.createStatement();
sql = "SELECT * FROM IMAGETABLE WHERE ID="+ID+"";
ResultSet result = stmt.executeQuery(sql);
if(result.next()){
in=result.getBinaryStream(3);//Since my data was in third column of table.
}
bin = new BufferedInputStream(in);
bout = new BufferedOutputStream(out);
int ch=0;
while((ch=bin.read())!=-1)
{
bout.write(ch);
}
} catch (SQLException ex) {
Logger.getLogger(DisplayImage.class.getName()).log(Level.SEVERE, null, ex);
}finally{
try{
if(bin!=null)bin.close();
if(in!=null)in.close();
if(bout!=null)bout.close();
if(out!=null)out.close();
if(conn!=null)conn.close();
}catch(IOException | SQLException ex){
System.out.println("Error : "+ex.getMessage());
}
}
}
}
After the execution of your jsp or html file you will see the image on screen.
You can also create custom tag for displaying image.
1) create custom tag java class and tld file.
2) write logic to display image like conversion of byte[] to string by Base64.
so it is used for every image whether you are displaying only one image or multiple images in single jsp page.