JDBC, jsp,servlet

              JDBC (Java Database Connectivity)


in above image
orange color: classes hai
Blue color: interfaces hai
download mysql driver and set classpath : youtube link


                                         

FirstJDBC.java

import java.sql.*;

class FirstJDBC{

    public static void main(String args[]){

        try {
     // load the driver
       Class.forName("com.mysql.cj.jdbc.Driver");

        // creating connection
        String url="jdbc:mysql://localhost:3306/youtube";
        String username="root";
        String password="root";
        Connection con=DriverManager.getConnection(url,username,password);

        if(con.isClosed()){
            System.out.println("Connection is Closed");
        }else{
            System.out.println("Connection is Created....");
        }
           
        } catch (Exception e) {
         
            System.out.println("Error is : "+e);
        }
    }
}
E:\java\jdbc>javac FirstJDBC.java E:\java\jdbc>java FirstJDBC Connection is Created.... E:\java\jdbc>

InsertJDBC.java  // are yr table create krenge

import java.sql.*;

class InsertJDBC{

    public static void main(String args[]){

        try {
     // load the driver
       Class.forName("com.mysql.cj.jdbc.Driver");

        // creating connection
        String url="jdbc:mysql://localhost:3306/youtube";
        String username="root";
        String password="root";
        Connection con=DriverManager.getConnection(url,username,password);

        //create query
         String q="create table table1(tId int(20) primary key auto_increment,tName varchar(200) not null,tCity varchar(400))";
         Statement stmt=con.createStatement();
         stmt.executeUpdate(q);
          // stmt.executeUpdate(q); chlne ke baad hi neeche wala code chalega
         System.out.println("table created in database..");

        con.close();
           
        } catch (Exception e) {
         
            System.out.println("Error is : "+e);
        }
    }
}
E:\java\jdbc>javac InsertJDBC.java E:\java\jdbc>java InsertJDBC table created in database..

InsertDataJDBC.java

import java.sql.*;

class InsertDataJDBC{

    public static void main(String args[]){

        try {
     // load the driver
       Class.forName("com.mysql.cj.jdbc.Driver");

        // creating connection
        String url="jdbc:mysql://localhost:3306/youtube";
        String username="root";
        String password="root";
        Connection con=DriverManager.getConnection(url,username,password);

        //create query
         String q="insert into table1(tName,tCity) values(?,?)";
        //  get the preparedStatement object
        PreparedStatement pstmt=con.prepareStatement(q);

        //set the values to query
        pstmt.setString(1, "Shivam");
        pstmt.setString(2, "Kanpur");
         pstmt.executeUpdate();
          // stmt.executeUpdate(q); chlne ke baad hi neeche wala code chalega
         System.out.println("values inserted....");

        con.close();
           
        } catch (Exception e) {
         
            System.out.println("Error is : "+e);
        }
    }
}
E:\java\jdbc>javac InsertDataJDBC.java E:\java\jdbc>java InsertDataJDBC values inserted....

mysql> use youtube;
Database changed
mysql> select * from table1;
+-----+--------+--------+
| tId | tName  | tCity  |
+-----+--------+--------+
|   1 | Shivam | Kanpur |
+-----+--------+--------+
1 row in set (0.07 sec)

InsertDataViaInputJDBC.java

import java.sql.*;
import java.io.*;

class InsertDataViaInputJDBC{

    public static void main(String args[]){

        try {
     // load the driver
       Class.forName("com.mysql.cj.jdbc.Driver");

        // creating connection
        String url="jdbc:mysql://localhost:3306/youtube";
        String username="root";
        String password="root";
        Connection con=DriverManager.getConnection(url,username,password);

        //create query
         String q="insert into table1(tName,tCity) values(?,?)";
        //  get the preparedStatement object
        PreparedStatement pstmt=con.prepareStatement(q);
   
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        System.out.println("Enter Name : ");
        String name=br.readLine();

        System.out.println("Enter City : ");
        String city= br.readLine();
       
        //set the values to query
        pstmt.setString(1, name);
        pstmt.setString(2, city);
         pstmt.executeUpdate();
          // stmt.executeUpdate(q); chlne ke baad hi neeche wala code chalega
         System.out.println("values inserted....");

        con.close();
           
        } catch (Exception e) {
         
            System.out.println("Error is : "+e);
        }
    }
}
E:\java\jdbc>javac InsertDataViaInputJDBC.java E:\java\jdbc>java InsertDataViaInputJDBC Enter Name : Anmol Garg Enter City : Saharanpur values inserted....
mysql> select * from table1;
+-----+-------------+------------+
| tId | tName       | tCity      |
+-----+-------------+------------+
|   1 | Shivam      | Kanpur     |
|   2 | Ankit Kumar | Noida      |
|   3 | Anmol Garg  | Saharanpur |
+-----+-------------+------------+
3 rows in set (0.00 sec)

InsertImageJDBC.java

BLOB Types

Object typeValue length that the object can hold
TINYBLOBfrom 0 to 255 bytes
BLOBfrom 0 to 65535 bytes
MEDIUMBLOBfrom 0 to 16 777 215 bytes
LONGBLOBfrom 0 to 4 294 967 295 bytes

--

Type of BLOBMaximum amount of Data that can be storedOverhead
TINYBLOBUp to 255 bytes1 byte
BLOBUp to 64 Kb2 bytes
MEDIUMBLOBUp to 16 Mb3 bytes
LONGBLOBUp to 4 Gb1 Bytes
mysql> create table images(id int primary key auto_increment, pic blob); Query OK, 0 rows affected (0.17 sec)

import java.sql.*;
import java.io.*;
class InsertImageJDBC{

    public static void main(String args[]){

        try {
     // load the driver
       Class.forName("com.mysql.cj.jdbc.Driver");

        // creating connection
        String url="jdbc:mysql://localhost:3306/youtube";
        String username="root";
        String password="root";
        Connection con=DriverManager.getConnection(url,username,password);

        //create query
         String q="insert into images(pic) values(?)";
        //  get the preparedStatement object
        PreparedStatement pstmt=con.prepareStatement(q);
       
        FileInputStream fis=new FileInputStream("C:\\Users\\Lenovo\\Pictures\\Screenshots\\Screenshot (812).png");
         
        //set the values to query
        pstmt.setBinaryStream(1,fis,fis.available());
       
         pstmt.executeUpdate();
          // stmt.executeUpdate(q); chlne ke baad hi neeche wala code chalega
         System.out.println("image inserted....");

        con.close();
           
        } catch (Exception e) {
         
            System.out.println("Error is : "+e);
        }
    }
}
E:\java\jdbc>javac InsertImageJDBC.java E:\java\jdbc>java InsertImageJDBC image inserted....

Work in netbeans
Add JAR to Java project in Neatbeans 12 using Maven
                                        Run Java Program Using NetBeans 12.0

ConnectionProvider.java


package com.mycompany.jdbc;

import java.sql.*;
public class ConnectionProvider{

   private static Connection con;

  public static Connection getConnection(){
 
try{


  if(con==null){
        // load the driver
       Class.forName("com.mysql.cj.jdbc.Driver");
             // creating connection
         con=DriverManager.getConnection("jdbc:mysql://localhost:3306/youtube","root","root");
}
}catch(Exception e){
  System.out.println("Error is : "+e);
}
return con;

}

}


Main.java

package com.mycompany.jdbc;

import java.sql.*;
public class Main{

  public static void main(String args[]){

  try{

   Connection conn=ConnectionProvider.getConnection();
   System.out.println("Connection Successfull....");


}catch(Exception e){

   e.printStackTrace();
}

}

}

UpdateDataJDBC.java

package com.mycompany.jdbc;

import java.sql.*;
import java.io.*;
public class UpdateDataJDBC{

  public static void main(String args[]){

  try{

   Connection conn=ConnectionProvider.getConnection();
   
   String q="update table1 set tName=? , tCity=? where tId=?";
PreparedStatement pstmt=conn.prepareStatement(q);
   BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
   System.out.println("Enter new Name : ");
   String name=br.readLine();

 System.out.println("Enter new City Name : ");
 String city=br.readLine();

 System.out.println("Enter the student id: ");
 int id=Integer.parseInt(br.readLine());

pstmt.setString(1,name);
pstmt.setString(2,city);

pstmt.setInt(3,id);

pstmt.executeUpdate();

System.out.println("updation done....");

}catch(Exception e){

   e.printStackTrace();
}

}

}
SelectJDBC.java

package com.mycompany.jdbc;

import java.sql.*;
import java.io.*;
public class SelectJDBC{

  public static void main(String args[]){

  try{

   Connection conn=ConnectionProvider.getConnection();
   
   String q="select * from table1";
   
Statement stmt=conn.createStatement();
ResultSet sett=stmt.executeQuery(q);

 while(sett.next()){
   int id=sett.getInt(1);
   String name=sett.getString(2);
   String city=sett.getString(3);
   
   System.out.println(id+" : "+name+" : "+city);

}
   

conn.close();

}catch(Exception e){

   e.printStackTrace();
}

}

}


jsp & Servlet


Working in eclipse ide:

nodejs res.send() equivalent:

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
   // TODO Auto-generated method stub
     
   response.getWriter().println("<h1>Hello World!</h1>");
//    response.getWriter().append("Served at: ").append(request.getContextPath());
}
or
PrintWriter out=response.getWriter();
out.println("jo bhi print krans chaho");


url se value fetch krna:
request.getParameter("variable");
url :http://localhost:8080/servlet2/tmpServlet?value1=Ankit&value2=kumar
PrintWriter out=response.getWriter();
out.println("value 1"+request.getParameter("value1"));
out.println("value 2"+request.getParameter("value2"));

servlet life cycle:
5 jsp scripting element:


JSP scriptlet tag:

syntax:
  1. <%  java source code %>  

Examples:
  1. <body>  
  2. <% out.print("welcome to jsp"); %>  
  3. </body>  

Example of JSP scriptlet tag that prints the user name:

File: index.html

  1. <html>  
  2. <body>  
  3. <form action="welcome.jsp">  
  4. <input type="text" name="uname">  
  5. <input type="submit" value="go"><br/>  
  6. </form>  
  7. </body>  
  8. </html>  

File: welcome.jsp

  1. <html>  
  2. <body>  
  3. <%  
  4. String name=request.getParameter("uname");  
  5. out.print("welcome "+name);  
  6. %>  
  7. </form>  
  8. </body>  
  9. </html> 

JSP expression tag:

syntax:
  1. <%=  statement %>  
Examples:
  1. <body>  
  2. <%= "welcome to jsp" %>  
  3. </body>  
Note: Do not end your statement with semicolon in case of expression tag.

Example of JSP expression tag that prints current time:

  1. Current Time: <%= java.util.Calendar.getInstance().getTime() %>  
  2. or 
  3.   <%= new java.util.Date() %>
Example of JSP expression tag that prints the user name:

File: index.jsp

  1. <html>  
  2. <body>  
  3. <form action="welcome.jsp">  
  4. <input type="text" name="uname"><br/>  
  5. <input type="submit" value="go">  
  6. </form>  
  7. </body>  
  8. </html>  

File: welcome.jsp

  1. <html>  
  2. <body>  
  3. <%= "Welcome "+request.getParameter("uname") %>  
  4. </body>  
  5. </html> 

JSP Declaration Tag:

syntax:
  1. <%!  field or method declaration %>  


Difference between JSP Scriptlet tag and Declaration tag:

Jsp Scriptlet TagJsp Declaration Tag
The jsp scriptlet tag can only declare variables not methods.The jsp declaration tag can declare variables as well as methods.
The declaration of scriptlet tag is placed inside the _jspService() method.The declaration of jsp declaration tag is placed outside the _jspService() method.

Example of JSP declaration tag that declares field:
  1. <%! int data=50; %>  
  2. <%= "Value of the variable is:"+data %>  

Example of JSP declaration tag that declares method:
  1. <%!   
  2. int cube(int n){  
  3. return n*n*n*;  
  4. }  
  5. %>  
  6. <%= "Cube of 3 is:"+cube(3) %>  

dusri file jsp me load krna taki web page me display ho jaye:

<body>
        <!-- for adding static content -->
        <%@ include file="file1.txt" %>
        <br>
        <!-- for adding dynamic content -->
        <jsp:include page="file2.txt"/>

</body>

another class ke method ko call krna:

UserDefined.java
package tmppackage;

public class UserDefined {

     public String getText(String name) {
         return "Person Name is : "+name;
     }
}

tmpJsp.jsp

<%@ page import="tmppackage.UserDefined" %>
 <% out.print(newUserDefined().getText("Ankit Kumar")); %>

output on browser:

Person Name is : Ankit Kumar 

Built in class import in jsp file:

<%@ page import="java.util.Date" %>
<%= new Date() %>

output on browser:

Mon Oct 11 18:11:34 IST 2021 

ek hi tag me multiple class import kr ske hain:

<%@ page import="tmppackage.UserDefined,java.util.Date" %>

Assignment: (Login ko click krne pr login page khule and so on): Based on MVC concept

Home Page

solution:

index.jsp

<body>
   <h1>Home Page</h1>
   <ul>
   <li>   <a href="<%=request.getContextPath() %>/Controller?page=login">Login</a></li>
 <li>  <a href="<%=request.getContextPath() %>/Controller?page=signUp">Sign Up</a> </li>
  <li> <a href="<%=request.getContextPath() %>/Controller?page=about">About</a>  </li>
   </ul>
</body>

Controller.java (servlet file)

   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      String param=request.getParameter("page");
      if(param.equals("login")) {
         getServletContext().getRequestDispatcher("/login.jsp").forward(request,response);
      }else if(param.equals("signUp")) {
         getServletContext().getRequestDispatcher("/signUp.jsp").forward(request,response);
      }else if(param.equals("about")) {
         getServletContext().getRequestDispatcher("/about.jsp").forward(request,response);
      }else {
      getServletContext().getRequestDispatcher("/notFound.jsp").forward(request,response);
   }
   }

login.jsp

<body>
   login page
</body>


Form ko sumit krne pr uski values dusri file ki help se display krana:

Without Using Controller:

form.jsp
<form action="submit.jsp">
 
    <div>
     <label>Full Name</label>
     <input type="text" name="full_name" required>
    </div>
        <div>
     <label>Gender</label>
     <input type="radio" name="gender" value="male" checked>Male
     <input type="radio" name="gender" value="female">Female
    </div>
  <div>
     <label>Language know</label>
     <input type="checkbox" name="language" value="English">English
     <input type="checkbox" name="language" value="Hindi">Hindi
     <input type="checkbox" name="language" value="French">French
     
    </div>
     <div>
     <label>Country</label>
     <select name="country">
     <option value="India">India</option>
     <option value="USA">USA</option>
     <option value="UK">UK</option>
     <option value="Japan">Japan</option>
     <option value="Nepal">Nepal</option>
     </select>
     
    </div>
    <div>
    <input type="submit" value="submit">
    </div>
 
  </form>

submit.jsp
<body>
 
 
  Name : <%= request.getParameter("full_name") %> <br>
  Gender : <%= request.getParameter("gender") %><br>
  Language Know : <%
   String[] languages=request.getParameterValues("language");

   if(languages!=null){
     for(int i=0;i<languages.length;i++){
       out.print(languages[i]+"<br>");
     }
   }else{
     out.print("Not Selected");
   }
  %>
  Country : <%= request.getParameter("country") %> <br>
</body>

Using Controller:

form.jsp
 <form action="<%= request.getContextPath() %>/Controller" method="post">...baki same as above

Controller.java (servlet)

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         String name=request.getParameter("full_name");
         String gender=request.getParameter("gender");
         String[] languages=request.getParameterValues("language");
         String country=request.getParameter("country");
       
         PrintWriter out=response.getWriter();
         
         
         out.println(name+"<br>"+gender+"<br>");
         if(languages!=null) {
             for(int i=0;i<languages.length;i++) {
                 out.println(languages[i]+"<br>");
             }
         }else {
             out.println("Not Selected");
         }
         
         out.println(country);
        doGet(request, response);
    }



                                    javaBeans awareness

JavaBeans are classes that encapsulate many objects into a single object (the bean).





-----------

references:

https://www.javatpoint.com


----

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