JDBC and jdbc connect to the database

JDBC and jdbc connect to the database

JDBC-development instance-MVC Mode

1. Configure the database connection information in web. xml

Web. xml:

<Context-param>

<Param-name> server </param-name> // host name

<Param-value> localhost </param-value>

</Context-param>

<Context-param>

<Param-name> db </param-name> // Database

<Param-value> test </param-value>

</Context-param>

<Context-param>

<Param-name> user </param-name> // user name

<Param-value> root </param-value>

</Context-param>

<Context-param>

<Param-name> password </param-name> // password

<Param-value> 1234 </param-value>

</Context-param>

2. Data Layer-create entity class Student. java

Student. java:

Package gh. test. entity;

　　

Public class Student {

Private int id;

Private String name;

Private int gender;

Private int age;

Private String address;

Private String tel;

Public void setId (int id) {// student id

This. id = id;

}

Public int getId (){

Return id;

}

Public void setName (String name) {// name

This. name = name;

}

Public String getName (){

Return name;

}

Public void setGender (int gender) {// gender

This. gender = gender;

}

Public int getGender (){

Retuen gender;

}

Public void setAge (int age) {// age

This. age = age;

}

Public int getAge (){

Return age;

}

Public void setAddress (String address) {// address

This. address = address;

}

Public String getAddress (){

Return address;

}

Public void setTel (String tel ){

Return tel;

}

}

3. Data access layer-create database operation class DB. java & StudentDao class StudentDao. java

DB. java:

Package gh. test. dao;

 

Import java. SQL. DriverManager;

Import java. SQL. Connection;

Import java. SQL. PreparedStatement;

Import java. SQL. ResultSet;

Import java. SQL. SQLException;

　　

Public class DB {

Connection conn = null;

PreparedStatement ps = null;

ResultSet rs = null;

Public Connection getConn

(String server, String db, String user, String password) throws ClassNotFoundException, InstantiationException, IllegalAccessException, SQLException {// get object

String driver = "com. mysql. jdbc. Driver ";

String url = "jdbc: mysql: //" + server + ": 3306/" + db + "? User = "+ user +" & password = "+ password +" & characterEncoding = UTF-8 ";

Class. forName (driver); // load the driver

Connection conn = DriverManager. getConnection (url); // create a Connection object

Return conn;

}

Public ResultSet executeQuery (String SQL, String [] params) {// execute the query operation

Try {

Ps = conn. prepareStatement (SQL );

If (params! = Null ){

For (int I = 0; I <params. length; I ++ ){

Ps. setString (I + 1, params [I]);

}

}

Rs = ps.exe cuteQuery ();

}

Catch (SQLException ex ){

Ex. printStackTrace ();

}

Return rs;

}

Public int executeUpdate (String SQL, String [] params) {// execute the update operation

Int n = 0;

Try {

Ps = conn. prepareStatement (SQL );

If (params! = Null ){

For (int I = 0; I <params. length; I ++ ){

Ps. setString (I + 1, params [I]);

}

N = ps.exe cuteUpdate ();

}

} Catch (SQLException ex ){

Ex. printStackTrace ();

}

Return n;

}

Public void closeAll (){

If (rs! = Null ){

Try {

Rs. close ();

} Catch (SQLException ex ){

Ex. printStackTrace ();

}

}

If (ps! = Null ){

Try {

Ps. close ();

} Catch (SQLException ex ){

Ex. printStackTrace ();

}

}

If (conn! = Null ){

Try {

Conn. close ();

} Catch (SQLException ex ){

Ex. printStackTrace ();

}

}

}

}

 

StudentDao. java:

Package gh. test. dao;

Import gh. test. entity. Student;

　　

Public class StudentDao extends DB {

Public int addStudent (Student student ){

String name = student. getName ();

String gender = student. getGender () + "";

String age = student. getAge () + "";

String address = student. getAddress ();

String tel = student. getTel ();

String [] params = new String [] {name, gender, age, address, tel };

String SQL = "insert into studentInfo values (?,?,?,?,?) ";

Int result = super.exe cuteUpdate (SQL, params );

Return result;

}

}

 

4. Graphic Display layer &logic processing -addstudent.html & AddStudentServlet. java

AddStudent.html:

<Html>

<Head>

<Meta http-equiv = "Content-Type" content = "text/html; charset = UTF-8">

<Title> Add Student Information </title>

</Head>

<Body>

<Form name = "form1" action = "AddStudentServlet" method = "post">

<Table>

<Tr>

<Th colspan = "2"> Student Information </th>

</Tr>

<Tr>

<Td> name: </td>

<Td> <input type = "text" name = "name"/> </td>

</Tr>

<Tr>

<Td> Gender: </td>

<Td>

<Input type = "radio" name = "gender" value = "0" check = "checked"/> male & nbsp;

<Input type = "radio" name = "gender" value = "1"/> female

</Td>

</Tr>

<Tr>

<Td> Age: </td>

<Td>

<Select name = "age">

<Option value = "18" select = "selected"> 18 </option>

<Option value = "19"> 19 </option>

<Option value = "20"> 20 </option>

<Option value = "21"> 21 </option>

<Option value = "22"> 22 </option>

</Select>

</Td>

</Tr>

<Tr>

<Td> address: </td>

<Td> <input type = "text" name = "address"/> </td>

</Tr>

<Tr>

<Td> Tel: </td>

<Td> <input type = "text" name = "tel"/> </td>

</Tr>

<Tr>

<Td colspan = "2" align = "center">

<Input type = "submit" name = "tj" value = "submit" onclick = "check ();"/> & nbsp;

<Input type = "reset" name = "cz" value = "reset"/>

</Td>

</Tr>

</Table>

</Form>

<Script language = "javascript">

Function check (){

If (document. form1.name. value = ""){

Alert ("enter your name! ");

Document. form1.name. focus ();

Return false;

}

If (document. form1.age. value = ""){

Alert ("Enter age! ");

Document. form1.age. focus ();

Return false;

}

If (document. form1.address. value = ""){

Alert ("Enter the address! ");

Document. form1.address. focus ();

Return false;

}

If (document. form1.tel. value = ""){

Alert ("Enter your phone number! ");

Document. form1.tel. focus ();

Return false;

}

Return true;

}

</Script>

</Body>

</Html>

 

 

AddStudentServlet. java:

Package gh. test. servlet;

Import java. io. IOException;

Import java. io. PrintWriter;

Import java. SQL. SQLException;

Import javax. servlet. ServletContent;

Import javax. servlet. ServletException;

Import javax. servlet. http. HttpServlet;

Import javax. servlet. http. HttpServletRequest;

Import javax. servlet. http. HttpServletResponse;

 

Import gh. test. entity. Student;

Import gh. test. dao. StudentDao;

Public class AddStudentServlet extends HttpServlet {

Private static final long serialVersionUID = 1L;

Public AddStudentServlet (){

Super ();

}

Public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

DoPost (request, response );

}

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

Request. setCharacterEncoding ("UTF-8 ");

Response. setContentType ("text/html; charset = UTF-8 ");

PrintWriter out = response. getWriter ();

String name = request. getParameter ("name ");

Int gender = Integer. parseInt (request. getParameter ("gender "));

Int age = Integer. parseInt (request. getParameter ("age "));

String address = request. getParameter ("address ");

String tel = request. getParameter ("tel ");

Student student = new Student ();

Student. setName (name );

Student. setGender (gender );

Student. setAge (age );

Student. setAddress (address );

Student. setTel (tel );

ServletContext ctx = this. getServletContext ();

String server = ctx. getInitParameter ("server ");

String db = ctx. getInitParameter ("db ");

String user = ctx. getInitParameter ("user ");

String password = ctx. getInitParameter ("password ");

StudentDao studentDao = new StudentDao ();

Try {

StudentDao. getConn (server, db, user, password );

If (studentDao. addStudent (student) = 1 ){

Out. print ("new student information added successfully! <Br> ");

}

Else {

Out. print ("failed to add! <Br> ");

}

Out. print ("<a href='addStudent.html '> return </a> ");

} Catch (ClassNotFoundException ex ){

Ex. printStackTrace ();

} Catch (Exception ex ){

Ex. printStackTrace ();

}

}

}