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Mysql BIT_LENGTH() Function Example Using Java Servlet

Posted in : Java Posted on : September 15, 2011 at 6:35 PM Comments : [ 0 ]

In this tutorial you will learn how to use bit_length() function of mysql with java servlet

Mysql BIT_LENGTH() Function Example Using Java Servlet

In this tutorial you will learn how to use bit_length() function of mysql with java servlet

BIT_LENGTH() method of mysql, a string is passed into its parameter and then it gives back the length of that string in bits.

Syntax :

bit_length('expression')

Here expression can be a string, a character, special character or numbers.

Now, since I have to use this function in java servlet program, therefore I have created a java servlet class named MysqlBitLengthServlet which extends the HttpServlet class. In the body of class I overridden the method doGet() and created an objects of HttpServletRequest and HttpServletResponse into its parameter. Inside the doGet() method first I set the mime type that in which format the browser will show the output. In the next line I used the getWriter() method of ServletResponse interface with the object of HttpServletResponse. HttpServletResponse interface extends this method from the ServletResponse. In Next step I am taking an input using the getParameter() method of ServletRequest with the object of HttpServletRequest. In continue we have to establish a connection between java code and database system. So, since I am using Mysql in the example given below therefore, I am loading the driver of mysql and make a connection by using the getConnection() method of DriverManager class. It returns a Connection. Further I am passing the query "SELECT BIT_LENGTH("+"'"+bt+"'"+")"; (This query will return the length of string for the value input by the user. In this query bt is a variable name that stores the value that is given by the user. getParameter() method is used to take and store the value of this variable in source/java code.) into the parameter of prepareStatement() method of Connection interface which gives an object of PreparedStatement interface. In the next line I used the executeQuery() method of PreparedStatement interface which returns a ResultSet object that holds the result of query. At last I have extracted the result from the ResultSet object.

Example :

BitLength.html

<!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>String's length in bit</title>
</head>
<body>
<form method="get" action="MysqlBitLengthServlet">
<table><tr><td>Enter a String <input type="text" name="txtName"/></td></tr>
<tr><td align="center"><input type="submit" value="Find BitLength"/>
</table>
</form>
</body>
</html>

MysqlBitLengthServlet.java

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MysqlBitLengthServlet extends HttpServlet
{
 public void doGet(HttpServletRequest request, HttpServletResponse response)
  throws IOException, ServletException
  {
	response.setContentType("text/html");
	PrintWriter out = response.getWriter();

	String bt = request.getParameter("txtName");
	
	String className = "com.mysql.jdbc.Driver";
	String url = "jdbc:mysql://192.168.10.13";
	String user = "root";
	String password = "root";
	
	Connection con;
	PreparedStatement ps;
	ResultSet rs;
	
	try
	{
	 Class.forName(className);
	 con = DriverManager.getConnection(url, user, password);
	 
	 String sql = "SELECT BIT_LENGTH("+"'"+bt+"'"+")";
	 
	 ps= con.prepareStatement(sql);
	 rs= ps.executeQuery();
	 
	 while(rs.next())
	 {
	  sql = rs.getString(1);
	  out.println(sql);
	 }
	}
	catch(SQLException sx)
	{
	  out.println(sx);
	}
	catch(ClassNotFoundException cx)
	{
	  out.println(cx);
	}
  }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" 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">
<display-name>mysqlStringFunction</display-name>
<servlet>
<servlet-name>MysqlBitLengthServlet</servlet-name>
<servlet-class>MysqlBitLengthServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>MysqlBitLengthServlet</servlet-name>
<url-pattern>/MysqlBitLengthServlet</url-pattern>
</servlet-mapping>
</web-app>

Output

When you will execute the above example you will get the output as :