UploadImage.java Source code

Introduction

Here is the source code for UploadImage.java

Source

/***
*  A sample program to demonstrate how to use servlet to 
*  load an image file from the client disk via a web browser
*  and insert the image into a table in Oracle DB.
*  
*  Copyright 2005 COMPUT 391 Team, CS, UofA                             
*  Author:  Fan Deng
*                                                                  
*  Licensed under the Apache License, Version 2.0 (the "License");         
*  you may not use this file except in compliance with the License.        
*  You may obtain a copy of the License at                                 
*      http://www.apache.org/licenses/LICENSE-2.0                          
*  Unless required by applicable law or agreed to in writing, software
*  distributed under the License is distributed on an "AS IS" BASIS,
*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*  See the License for the specific language governing permissions and
*  limitations under the License.
*
*
*  the table shall be created using the following
  CREATE TABLE pictures (
        pic_id int,
   pic_desc  varchar(100),
   pic  BLOB,
   primary key(pic_id)
  );
*
*  One may also need to create a sequence using the following 
*  SQL statement to automatically generate a unique pic_id:
*
*   CREATE SEQUENCE pic_id_sequence;
*
***/

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
import java.util.*;
import oracle.sql.*;
import oracle.jdbc.*;

/**
 *  The package commons-fileupload-1.0.jar is downloaded from 
 *         http://jakarta.apache.org/commons/fileupload/ 
 *  and it has to be put under WEB-INF/lib/ directory in your servlet context.
 *  One shall also modify the CLASSPATH to include this jar file.
*/
import org.apache.commons.fileupload.DiskFileUpload;
import org.apache.commons.fileupload.FileItem;

public class UploadImage extends HttpServlet {
    public String response_message;

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //  change the following parameters to connect to the oracle database
        String username = "wang8";
        String password = "Steelrose101";
        String drivername = "oracle.jdbc.driver.OracleDriver";
        String dbstring = "jdbc:oracle:thin:@gwynne.cs.ualberta.ca:1521:CRS";
        int pic_id;

        try {
            //Parse the HTTP request to get the image stream
            DiskFileUpload fu = new DiskFileUpload();
            List FileItems = fu.parseRequest(request);

            // Process the uploaded items, assuming only 1 image file uploaded
            Iterator i = FileItems.iterator();
            FileItem item = (FileItem) i.next();
            while (i.hasNext() && item.isFormField()) {
                item = (FileItem) i.next();
            }

            //Get the image stream
            InputStream instream = item.getInputStream();

            // Connect to the database and create a statement
            Connection conn = getConnected(drivername, dbstring, username, password);
            Statement stmt = conn.createStatement();

            /*
             *  First, to generate a unique pic_id using an SQL sequence
             */
            ResultSet rset1 = stmt.executeQuery("SELECT pic_id_sequence.nextval from dual");
            rset1.next();
            pic_id = rset1.getInt(1);

            //Insert an empty blob into the table first. Note that you have to 
            //use the Oracle specific function empty_blob() to create an empty blob
            stmt.execute("INSERT INTO pictures VALUES(" + pic_id + ",'test',empty_blob())");

            // to retrieve the lob_locator 
            // Note that you must use "FOR UPDATE" in the select statement
            String cmd = "SELECT * FROM pictures WHERE pic_id = " + pic_id + " FOR UPDATE";
            ResultSet rset = stmt.executeQuery(cmd);
            rset.next();
            BLOB myblob = ((OracleResultSet) rset).getBLOB(3);

            //Write the image to the blob object
            OutputStream outstream = myblob.getBinaryOutputStream();
            int size = myblob.getBufferSize();
            byte[] buffer = new byte[size];
            int length = -1;
            while ((length = instream.read(buffer)) != -1)
                outstream.write(buffer, 0, length);
            instream.close();
            outstream.close();

            stmt.executeUpdate("commit");
            response_message = " Upload OK!  ";
            conn.close();

        } catch (Exception ex) {
            //System.out.println( ex.getMessage());
            response_message = ex.getMessage();
        }

        //Output response to the client
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " + "Transitional//EN\">\n" + "<HTML>\n"
                + "<HEAD><TITLE>Upload Message</TITLE></HEAD>\n" + "<BODY>\n" + "<H1>" + response_message
                + "</H1>\n" + "</BODY></HTML>");
    }

    /*
    /*   To connect to the specified database
     */
    private static Connection getConnected(String drivername, String dbstring, String username, String password)
            throws Exception {
        Class drvClass = Class.forName(drivername);
        DriverManager.registerDriver((Driver) drvClass.newInstance());
        return (DriverManager.getConnection(dbstring, username, password));
    }
}