Servlet File Upload

Hi,

html
-----
    <form action="UploadForm" enctype="multipart/form-data" method="POST">
            <input type="file" name="file1"><br>
            <input type="Submit" value="Upload File"><br>
        </form>
web.xml
--------
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    <servlet>
        <servlet-name>UploadForm</servlet-name>
        <servlet-class>UploadFormServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>UploadForm</servlet-name>
        <url-pattern>/UploadForm</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>


servlet
------

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
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.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class UploadFormServlet extends HttpServlet {

    private static final String TMP_DIR_PATH = "c:\\tmp";
    private File tmpDir;
    private static final String DESTINATION_DIR_PATH = "/files";
    private File destinationDir;

    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        tmpDir = new File(TMP_DIR_PATH);
        if (!tmpDir.isDirectory()) {
            throw new ServletException(TMP_DIR_PATH + " is not a directory");
        }
        String realPath = getServletContext().getRealPath(DESTINATION_DIR_PATH);
        destinationDir = new File(realPath);
        if (!destinationDir.isDirectory()) {
            throw new ServletException(DESTINATION_DIR_PATH + " is not a directory");
        }

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        response.setContentType("text/plain");
        out.println("<h1>Servlet File Upload Example using Commons File Upload</h1>");
        out.println();

        DiskFileItemFactory fileItemFactory = new DiskFileItemFactory();
        /*
         *Set the size threshold, above which content will be stored on disk.
         */
        fileItemFactory.setSizeThreshold(1 * 1024 * 1024); //1 MB
        /*
         * Set the temporary directory to store the uploaded files of size above threshold.
         */
        fileItemFactory.setRepository(tmpDir);

        ServletFileUpload uploadHandler = new ServletFileUpload(fileItemFactory);
        try {
            /*
             * Parse the request
             */
            List items = uploadHandler.parseRequest(request);
            Iterator itr = items.iterator();
            while (itr.hasNext()) {
                FileItem item = (FileItem) itr.next();
                /*
                 * Handle Form Fields.
                 */
                if (item.isFormField()) {
                    out.println("File Name = " + item.getFieldName() + ", Value = " + item.getString());
                } else {
                    //Handle Uploaded files.
                    out.println("Field Name = " + item.getFieldName()
                            + ", File Name = " + item.getName()
                            + ", Content type = " + item.getContentType()
                            + ", File Size = " + item.getSize());
                    /*
                     * Write file to the ultimate location.
                     */
                    File file = new File(destinationDir, item.getName());
                    item.write(file);
                }
                out.close();
            }
        } catch (FileUploadException ex) {
            log("Error encountered while parsing the request", ex);
        } catch (Exception ex) {
            log("Error encountered while uploading file", ex);
        }

    }
}

Jars Needed

http://mirrors.ibiblio.org/pub/mirrors/maven2/org/apache/commons/commons-io/1.3.2/commons-io-1.3.2.jar

http://mirrors.ibiblio.org/pub/mirrors/maven2/commons-fileupload/commons-fileupload/1.2.1/commons-fileupload-1.2.1.jar

 

Thanks

Rajesh   Kumar Yuvaraj

use of identityHashCode() of System class

Hi,
    As we know that we can override the hashCode() method of Object class with our own representation,What if i want to get the original hashCode() of a specific object. For that jdk provides a method inside of System class. Please go through the following example.


public class HashCodeDemo {

    @Override
    public int hashCode() {
        return 20;
    }

    public static void main(String ar[]) {

        HashCodeDemo hashObj = new HashCodeDemo();
        System.out.println(hashObj);
        System.out.println(hashObj.toString());
        System.out.println(hashObj.hashCode());
        System.out.println(System.identityHashCode(hashObj));

    }
}

OutPut
--------
javaapplications.HashCodeDemo@14
javaapplications.HashCodeDemo@14
20
4072869


Thanks

Rajesh Kumar Yuvaraj

usage of Map.Entry interface in java collections

Hi,

    
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
// TODO code application logic here
// Create a hash map
        HashMap hm = new HashMap();
// Put elements to the map
        hm.put("John Doe", new Double(3434.34));
        hm.put("Tom Smith", new Double(123.22));
        hm.put("Jane Baker", new Double(1378.00));
        hm.put("Todd Hall", new Double(99.22));
        hm.put("Ralph Smith", new Double(-19.08));
// Get a set of the entries
        Set set = hm.entrySet();
// Get an iterator
        Iterator i = set.iterator();
// Display elements
        while (i.hasNext()) {
            Map.Entry me = (Map.Entry) i.next();
            System.out.print(me.getKey() + ": ");
            System.out.println(me.getValue());
        }
        System.out.println();
// Deposit 1000 into John Doe's account
        double balance = ((Double) hm.get("John Doe")).doubleValue();
        hm.put("John Doe", new Double(balance + 1000));
        System.out.println("John Doe's new balance: "
                + hm.get("John Doe"));
    }
}

what is SQLite ?

                                          SQLite  is a tiny, embedded RDBMS (~275kb) which is used by the most of the local/client storage in  application software such as web browsers.Simply its a embedded data base for web browsers.
Ex.  Mozilla stores the cookies information inside a cookie.sqlite  file in the location C:\Users\Mypc\AppData\Roaming\Mozilla\Firefox\Profiles\gwj7th6j.default.
 This file is encrypted internally.We can explore this data base using a firefox plug in called SQLite.

https://addons.mozilla.org/en-US/firefox/addon/sqlite-manager/

Thanks,

Rajesh Kumar Yuvaraj