This tutorial assumes you have understanding on how JDBC application
works. Before starting with database access through a servlet, make sure
you have proper JDBC environment setup along with a database.
For more detail on how to access database using JDBC and its environment setup you can go through our JDBC Tutorial.
To start with basic concept, let us create a simple table and create few records in that table as follows:
For more detail on how to access database using JDBC and its environment setup you can go through our JDBC Tutorial.
To start with basic concept, let us create a simple table and create few records in that table as follows:
Create Table
To create the Employees table in TEST database, use the following steps:Step 1:
Open a Command Prompt and change to the installation directory as follows:C:\> C:\>cd Program Files\MySQL\bin C:\Program Files\MySQL\bin>
Step 2:
Login to database as followsC:\Program Files\MySQL\bin>mysql -u root -p Enter password: ******** mysql>
Step 3:
Create the table Employee in TEST database as follows:mysql> use TEST; mysql> create table Employees ( id int not null, age int not null, first varchar (255), last varchar (255) ); Query OK, 0 rows affected (0.08 sec) mysql>
Create Data Records
Finally you create few records in Employee table as follows:mysql> INSERT INTO Employees VALUES (100, 18, 'Zara', 'Ali'); Query OK, 1 row affected (0.05 sec) mysql> INSERT INTO Employees VALUES (101, 25, 'Mahnaz', 'Fatma'); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Employees VALUES (102, 30, 'Zaid', 'Khan'); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Employees VALUES (103, 28, 'Sumit', 'Mittal'); Query OK, 1 row affected (0.00 sec) mysql>
Accessing a Database:
Here is an example which shows how to access TEST database using Servlet.// Loading required libraries import java.io.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; import java.sql.*; public class DatabaseAccess extends HttpServlet{ public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // JDBC driver name and database URL static final String JDBC_DRIVER="com.mysql.jdbc.Driver"; static final String DB_URL="jdbc:mysql://localhost/TEST"; // Database credentials static final String USER = "root"; static final String PASS = "password"; // Set response content type response.setContentType("text/html"); PrintWriter out = response.getWriter(); String title = "Database Result"; String docType = "<!doctype html public \"-//w3c//dtd html 4.0 " + "transitional//en\">\n"; out.println(docType + "<html>\n" + "<head><title>" + title + "</title></head>\n" + "<body bgcolor=\"#f0f0f0\">\n" + "<h1 align=\"center\">" + title + "</h1>\n"); try{ // Register JDBC driver Class.forName("com.mysql.jdbc.Driver"); // Open a connection Connection conn = DriverManager.getConnection(DB_URL, USER, PASS); // Execute SQL query Statement stmt = conn.createStatement(); String sql; sql = "SELECT id, first, last, age FROM Employees"; ResultSet rs = stmt.executeQuery(sql); // Extract data from result set while(rs.next()){ //Retrieve by column name int id = rs.getInt("id"); int age = rs.getInt("age"); String first = rs.getString("first"); String last = rs.getString("last"); //Display values out.println("ID: " + id + "<br>"); out.println(", Age: " + age + "<br>"); out.println(", First: " + first + "<br>"); out.println(", Last: " + last + "<br>"); } out.println("</body></html>"); // Clean-up environment rs.close(); stmt.close(); conn.close(); }catch(SQLException se){ //Handle errors for JDBC se.printStackTrace(); }catch(Exception e){ //Handle errors for Class.forName e.printStackTrace(); }finally{ //finally block used to close resources try{ if(stmt!=null) stmt.close(); }catch(SQLException se2){ }// nothing we can do try{ if(conn!=null) conn.close(); }catch(SQLException se){ se.printStackTrace(); }//end finally try } //end try } }Now let us compile above servlet and create following entries in web.xml
.... <servlet> <servlet-name>DatabaseAccess</servlet-name> <servlet-class>DatabaseAccess</servlet-class> </servlet> <servlet-mapping> <servlet-name>DatabaseAccess</servlet-name> <url-pattern>/DatabaseAccess</url-pattern> </servlet-mapping> ....Now call this servlet using URL http://localhost:8080/DatabaseAccess which would display following response:
Database Result
ID: 100, Age: 18, First: Zara, Last: Ali ID: 101, Age: 25, First: Mahnaz, Last: Fatma ID: 102, Age: 30, First: Zaid, Last: Khan ID: 103, Age: 28, First: Sumit, Last: Mittal
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