Introduction to Software engineering 01:javaweb connect SQL Server database and complete a login interface and its functional design.

1. Connect to the database
Package com.jaovo.msg.Util;
Import java.sql.*;

public class Dbutil {
public static Connection getconnection () {
Load Driver
String dbdrive= "Com.mysql.jdbc.Driver";
try {
try {
Class.forName (dbdrive). newinstance ();
} catch (Instantiationexception e) {

E.printstacktrace ();
} catch (Illegalaccessexception e) {

E.printstacktrace ();
}
} catch (ClassNotFoundException e) {

E.printstacktrace ();
}
Connecting to a database
Connection Connection=null;
String url= "Jdbc:mysql://localhost:3307/l_user";
try {
Connection=drivermanager.getconnection (URL, "root", "root");
} catch (SQLException e) {

E.printstacktrace ();
}
return connection;
}
public static void Close (Connection Connection) {
try {
if (connection! = null) {
Connection.close ();
}

} catch (SQLException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
}
public static void Close (PreparedStatement preparedstatement) {
try {
if (PreparedStatement! = null) {
Preparedstatement.close ();
}

} catch (SQLException e) {

E.printstacktrace ();
}
}
public static void Close (ResultSet ResultSet) {
try {
if (ResultSet! = null) {
Resultset.close ();
}

} catch (SQLException e) {

E.printstacktrace ();
}
}

}

Summary: Connect to a database step
1. Import java.sql Package
Import java.sql.*;
2. Load the database's connection address, user name and password.
Class.forName ("Com.mysql.jdbc.Driver");
3. Define the database's link address, user name and password.
String user = "root";
String password = "root";
String url = "Jdbc:mysql://localhost:3307/jaovo_msg";

4. Get the Connection object to the database.
Connection = Drivermanager.getconnection (Url,user,password);
5. Declare the SQL statement.
String sql = "SELECT * from User1";
6. Get the Statement object.
PreparedStatement = connection.preparestatement (sql);
7. Execute the SQL statement.
ResultSet = Preparedstatement.executequery ();
8. Process the return statement of the SQL statement.
while (Resultset.next ()) {
user = new User ();
User.setname (resultset.getstring ("user"));
User.setpassword (resultset.getstring ("password"));
Users.add (user);
}
9. Close the object
Dbutil.close (ResultSet);
Dbutil.close (PreparedStatement);
Dbutil.close (connection);
3. Login User Class
Package Com.jaovo.msg.model;

public class User {
private String name;
private String password;
Public String GetName () {
return name;
}
Public String GetPassword () {
return password;
}
public void SetName (String name) {
This.name=name;
}
public void SetPassword (String password) {
This.password=password;
}

}

4. Interface of program function method
Package Com.jaovo.msg.dao;

Import java.util.List;

Import Com.jaovo.msg.model.User;

Public interface Iuserdao {
Public list<user> load ();
Public User Load (String name);

}

5. Classes that implement functional methods

Package Com.jaovo.msg.dao;
Import Com.jaovo.msg.Util.DBUtil;
Import Com.jaovo.msg.model.User;
Import java.sql.*;
Import java.util.ArrayList;
Import java.util.List;
public class Userdaoimpl implements iuserdao{
@Override
Public User Load (String name) {

Connection Connection = Dbutil.getconnection ();
Preparing SQL statements
String sql = "SELECT * from user1 where user = '" +name+ "'";
To create a statement transfer object
PreparedStatement preparedstatement = null;
ResultSet ResultSet = null;
Only user objects can be placed in the collection
User user = null;
try {
PreparedStatement = connection.preparestatement (sql);
ResultSet = Preparedstatement.executequery ();
if (Resultset.next ()) {
user = new User ();
User.setpassword (resultset.getstring ("password"));
}
} catch (SQLException e) {

E.printstacktrace ();
}finally {
Close Resource
Dbutil.close (ResultSet);
Dbutil.close (PreparedStatement);
Dbutil.close (connection);
}
return user;
}
@Override
Public list<user> load () {
Connection Connection = Dbutil.getconnection ();
Preparing SQL statements
String sql = "SELECT * from User1";
To create a statement transfer object
PreparedStatement preparedstatement = null;
ResultSet ResultSet = null;
Only user objects can be placed in the collection
list<user> users = new arraylist<user> ();
User user = null;

try {
PreparedStatement = connection.preparestatement (sql);
ResultSet = Preparedstatement.executequery ();
while (Resultset.next ()) {
user = new User ();
User.setname (resultset.getstring ("user"));
User.setpassword (resultset.getstring ("password"));
Users.add (user);
}
} catch (SQLException e) {

E.printstacktrace ();
}finally {
Close Resource
Dbutil.close (ResultSet);
Dbutil.close (PreparedStatement);
Dbutil.close (connection);
}

return users;
}
}

6. User Login Interface
<!--login.jsp--
<%@ page language= "java" contenttype= "text/html; Charset=utf-8 "
pageencoding= "UTF-8"%>
<! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" "HTTP://WWW.W3.ORG/TR/HTML4/LOOSE.DTD" >
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 ">
<title> User Login </title>
<body>
<form action= "dologin.jsp" method= "Get" >
<table align= "center" width= "30%" border= "1" >
<tr><td> Login name:</td> s
<td><input type= "text" name= "username"/></td></tr>
<tr><td> Login Password:</td>
<td><input type= "password" name= "password"/></td></tr>
&LT;TR&GT;&LT;TD colspan= "2" align= "center" ><input type= "submit" value= "Login" ><td></tr>
</table>
</form>
</body>

7. Implement user Login.
<% @page import= "Com.jaovo.msg.dao.UserDaoImpl"%>
<% @page import= "Com.jaovo.msg.model.User"%>
<% @page import= "Java.util.List"%>
<%@ page language= "java" contenttype= "text/html; Charset=utf-8 "
pageencoding= "UTF-8"%>
<! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" "HTTP://WWW.W3.ORG/TR/HTML4/LOOSE.DTD" >

<%
The parameters that the receiving client passed over
String username = request.getparameter ("username");
String Password = request.getparameter ("password");
Userdaoimpl a=new Userdaoimpl ();

User user=a.load (username);
String Password1=user.getpassword ();//The password passed by the login window is more than the password queried in the database
if (Password.equals (Password1)) {
OUT.PRINTLN ("Login Successful");
}
Else
OUT.PRINTLN ("Input password or login name is wrong!") ");
%>

Introduction to Software engineering 01:javaweb connect SQL Server database and complete a login interface and its functional design.