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Mysql ASCII() Function Example Using Java Servlet

Posted in : Java Posted on : September 12, 2011 at 7:54 PM Comments : [ 0 ]

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

Mysql ASCII() Function Example Using Java Servlet

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

ASCII function of mysql returns an ascii code for a character or left most character of a string. ASCII (American Standard Code for Information Interchange) is a technique for representing a character numerically. This function returns 'null' and '0' for null and empty string respectively and it may return an error or can ignored for the characters which doesn't have ASCII code depends on the different RDBMS implementation.

Syntax :

ascii('expressions');

Here expression can be either a single character, special character or a string

Now, since I have to use this function in java servlet program, therefore I have created a java servlet class named MysqlAsciiServlet 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 ascii(" + "' " + aci + "' " + ")"; (This query will return an ascii code for the value input by the user. In this query aci is a variable name that stores the value that is taken by the user. getParameter() method is used to take and store the value in 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 :

ascii.html

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">

<title>Convert Character To Ascii Code</title>

</head>

<body>

<form method = "get" action="MysqlAsciiServlet">

<table>

<tr><td>Enter the character or string</td><td><input type="text" name = "txtName"/></td></tr>

<tr><td></td><td align="center"><input type="submit" value="Enter"/></td></tr>

</table>

</form>

</body>

</html>

MysqlAsciiServlet.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 MysqlAsciiServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws IOException, ServletException {
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		String className = "com.mysql.jdbc.Driver";
		String url = "jdbc:mysql://192.168.10.13";
		String user = "root";
		String password = "root";
		String aci = request.getParameter("txtName");

		Connection con;
		PreparedStatement ps, ps1;
		ResultSet rs, rs1;

		try {
			Class.forName(className);
			con = DriverManager.getConnection(url, user, password);
			String str = "select ascii(" + "'" + aci + "'" + ")";
			System.out.println(str);
			ps = con.prepareStatement(str);
			rs = ps.executeQuery();
			while (rs.next()) {
				aci = rs.getString(1);
				out.println(aci);
			}
		} 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>MysqlAsciiServlet</servlet-name>
<servlet-class>MysqlAsciiServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>MysqlAsciiServlet</servlet-name>
<url-pattern>/MysqlAsciiServlet</url-pattern>
</servlet-mapping>
</web-app>

Output :

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