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User Login with servlet (vi)

Source: Internet
Author: User
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We use the servlet to implement a user login function. first, the database 





DROP TABLE IF EXISTS ' user ';
CREATE TABLE ' user ' (
  ' id ' int (one) not NULL,
  ' username ' varchar () DEFAULT NULL,
  ' password ' varchar () DEFA ULT null,
  ' email ' varchar (default NULL,
  PRIMARY KEY (' id ')
) engine=innodb default Charset=utf8;

------------------------------
-Records of user
------------------------------
INSERT into ' user ' VALUES (' 1 ', ' Tom ', ' 123 ', ' tom@163.com ');
INSERT into ' user ' VALUES (' 2 ', ' Lucy ', ' 123 ', ' lucy@163.com ');


second, the front page



login.jsp 


<% @ page language = "java" contentType = "text / html; charset = UTF-16"
     pageEncoding = "UTF-16"%>
<! DOCTYPE html PUBLIC "-// W3C // DTD HTML 4.01 Transitional // EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv = "Content-Type" content = "text / html; charset = UTF-16">
<title> Insert title here </ title>
</ head>
<body>

<form action = "/ servlet_first / login" method = "post">
Username: <input type = "text" name = "username"> <br/>
Password: <input type = "password" name = "password"> <br/>
<input type = "submit" name = "login"> <br/>
</ form>

</ body>
</ html>


Third、Servlet 

package com.ken.login;

import java.io.IOException;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;

import com.ken.domain.User;
import com.ken.utils.DataSourceUtils;

public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

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

// 1. get username and password
String username = request.getParameter ("username");
String password = request.getParameter ("password");

// 2. Verify that the username and password are correct from the database
QueryRunner runner = new QueryRunner (DataSourceUtils.getDataSource ());

String sql = "select * from user where username =? And password =?";
User user = null;
try {
user = runner.query (sql, new BeanHandler <User> (User.class), username, password);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace ();
}

// 3. Different display information to the user according to the returned result
if (user! = null) {
// The user logs in successfully
response.getWriter (). write (user.toString ());
} else {
// user login failed
response.getWriter (). write ("sorry your username or password is wrong");
}
}

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

Fourth, connect to the database
  4.1 Tool class DataSourceUtils
package com.ken.utils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class DataSourceUtils {

private static DataSource dataSource = new ComboPooledDataSource ();

private static ThreadLocal <Connection> tl = new ThreadLocal <Connection> ();

// You can directly get a connection pool
public static DataSource getDataSource () {
return dataSource;
}

// Get the connection object
public static Connection getConnection () throws SQLException {

Connection con = tl.get ();
if (con == null) {
con = dataSource.getConnection ();
tl.set (con);
}
return con;
}

// start transaction
public static void startTransaction () throws SQLException {
Connection con = getConnection ();
if (con! = null) {
con.setAutoCommit (false);
}
}

// transaction is rolled back
public static void rollback () throws SQLException {
Connection con = getConnection ();
if (con! = null) {
con.rollback ();
}
}

// Commit and close resources and release from ThreadLocall
public static void commitAndRelease () throws SQLException {
Connection con = getConnection ();
if (con! = null) {
con.commit (); // transaction commit
con.close (); // Close the resource
tl.remove (); // Remove from thread binding
}
}

// Close the resource method
public static void closeConnection () throws SQLException {
Connection con = getConnection ();
if (con! = null) {
con.close ();
}
}

public static void closeStatement (Statement st) throws SQLException {
if (st! = null) {
st.close ();
}
}

public static void closeResultSet (ResultSet rs) throws SQLException {
if (rs! = null) {
rs.close ();
}
}

}

4.2 c3p0-config.xml 

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
	<default-config>
		<property name="user">root</property>
		<property name="password">123456</property>
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="jdbcUrl">jdbc:mysql:///servlet_first</property>
	</default-config> 
</c3p0-config>

Fifth、web.xml 

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://java.sun.com/xml/ns/javaee"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
	id="WebApp_ID" version="2.5">
	<display-name>servlet_first</display-name>
	<servlet>
		<servlet-name>abc</servlet-name>
		<servlet-class>com.ken.servlet.QuickStartServlet</servlet-class>
		<init-param>
			<param-name>url</param-name>
			<param-value>jdbc:mysql:///mydb</param-value>
		</init-param>
	</servlet>
	<servlet-mapping>
		<servlet-name>abc</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
	<servlet>
		<servlet-name>QuickStartServlet2</servlet-name>
		<servlet-class>com.ken.servlet.QuickStartServlet2</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>QuickStartServlet2</servlet-name>
		<url-pattern>/quickStartServlet2</url-pattern>
	</servlet-mapping>
	<servlet>
		<description></description>
		<display-name>LoginServlet</display-name>
		<servlet-name>LoginServlet</servlet-name>
		<servlet-class>com.ken.login.LoginServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>LoginServlet</servlet-name>
		<url-pattern>/login</url-pattern>
	</servlet-mapping>
</web-app>

 










 

                

                    
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