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Save data from JSP text box to database

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posted 18 years ago

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hi....i'm very new in JSP and Java...but now i handle a project that need to use this 2 Language....

the problem is that i need add the data that i keyin in the webapplication text box to my database....all the process i need to do in java...

in my webapplication only got 2 text box...one is Country Name and another one is Country Population....i want to save this 2 field to my database after i key in a value/data...

can any one who know this help me...really appreciate yr knowledge....Thanks..

Natasza Biecek

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Posts: 28

posted 18 years ago

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Hi,
also hello to all, it's my first post here...

You need two things to do that:
1. a html/jsp page to allow user to input data
2. a servlet to process incoming data

So, let's write dataInputPage.jsp

It is a very simple form having two edit-boxes named
'form_country_name' and 'form_country_population'.
This form posts user input to 'dataProcessingServlet' which
will be our backend...

Now, dataProcessingServlet.java

import java.io.*;
import java.lang.Integer;
import java.net.*;
import java.util.ArrayList;
import java.sql.*;
 
import javax.servlet.*;
import javax.servlet.http.*;
 
public class dataProcessingServlet extends HttpServlet {
    
    // not the best way...but it works
    public void init(ServletConfig config) throws ServletException {
super.init( config );
try {
    Class.forName("com.mysql.jdbc.Driver").newInstance();
} catch ( Exception ex ) {
    ex.printStackTrace();
}
    }
    
    private void addToDatabase ( String countryName, int countryPopulation ) {
// here we have country name and population ready
// to be added to database...
// very simple  example how to do it in MySQL
String dbURL = "jdbc:mysql://localhost/test_db";
try {    
    // we need db connection
    Connection conn = DriverManager.getConnection( dbURL, "root", null );
    // and statement to execute
    Statement st = conn.createStatement();
    // let's prepare SQL query: 'insert into...'
    String insertQuery = "insert into COUNTRIES ( NAME, POPULATION ) ";
    insertQuery += " values ( '" + countryName + "', " + countryPopulation + " )"; 
    // print it for debug (appears in server log files)
    System.out.println( "sql:" + insertQuery ); 
    // let's exetute
    st.execute ( insertQuery );    
    // that's all folks...
    conn.close();    
} catch ( SQLException ex ) {
    System.out.println( ex.getMessage() );
}
    }
 
    private void showErrorMessage ( ArrayList errMsgList, HttpServletResponse response )
    throws IOException {
PrintWriter out = response.getWriter();
out.println( "<html><body>" );
out.println( "Your request is very important for us, but:<br>" );
for (int i = 0; i < errMsgList.size(); i++ ) {
    out.println( "<li>" + errMsgList.get( i ) );
}
out.println( "<br><br>" );
out.println( "<a href='dataInputPage.jsp'>go back and correct you input please...</a>" );
out.println( "</body></html>" );
out.close();

}
    
    protected void processRequest( HttpServletRequest request, HttpServletResponse response )
    throws ServletException, IOException {
ArrayList errorMessages = new ArrayList();
String countryName;
String tempStr;
int countryPopulation = 0;
 
// basic validation
// for country name
countryName = (String)request.getParameter( "form_country_name" );
if ( countryName == null ) {
    errorMessages.add( "Country name parameter is missing (check input form!)" );
}
else {
    countryName = countryName.trim();
    if ( countryName.length() == 0 ) {
errorMessages.add("Country name is empty...");
    }
}

// and for population
tempStr = (String)request.getParameter( "form_country_population" );
if ( tempStr == null ) {
    errorMessages.add("Country population parameter is missing (check input form!)");
}
else {
    try {
countryPopulation = Integer.parseInt( tempStr );
    }
    catch( NumberFormatException ex ) {
errorMessages.add("Country population must be a number");
    }
}

//do we have any errors?
if ( errorMessages.size() != 0 ) {
    showErrorMessage( errorMessages, response );
}
else {
    addToDatabase ( countryName, countryPopulation );
}
    }
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
processRequest(request, response);
    }
    
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
processRequest(request, response);
    }    
}

Servlet performes basic validation of incoming data
and when something is wrong - shows list of problems...
When input data looks more-or-less good it establishes connection
to database and tries to insert data.

Please, treat all of this as a kind of draft, many things
should be done better...

regards,
Natasza
[ October 26, 2006: Message edited by: Natasza Biecek ]

Mag Yeoh

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Posts: 42

posted 18 years ago

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Thanks Natasza....this is my first time write a project using JSP...

oh...i forget to tell that, they dont want me to use servlet in my java file...need to use useBean/java....it is possible to do that???

Problem...
1. dont want use servlet in my java file
2. they need me to use "useBean"? It is possible to do that?
3. i using db4o database....i not using mySQL....

Mag Yeoh

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Posts: 42

posted 18 years ago

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Really Thanks a lot....yr coding very good....

Mag Yeoh

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posted 18 years ago

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Thanks Natasza ....

when i run your coding i having this error....i using eclipse to run jsp and java....

error is ....below is the error i get when i run your coding...i scare that i having a setting problem....you know what happen to this error..it is my setting problem.....
type Status report

message /SampleProject/Forum/SimpleExample.dataProcessingServlet

description The requested resource (/SampleProject/Forum/SimpleExample.dataProcessingServlet) is not available.

--------------------------------------------------------------------------------

Apache Tomcat/5.5.17

Adeel Ansari

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posted 18 years ago

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Mag Yeoh, all you need is a good tutorial or a book for JSP/Servlet beginners.

Mag Yeoh

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posted 18 years ago

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ok. Thanks your very much....Thanks for you help....i use your way idea to run in another way....

Haha....i copy right your idea....

anyway, thanks.....

Cheers....