Java Web实现用户登录界面

一、学习Java Web需要的技术：

Java语言基础：算法基础、常用数据结构、编程规范。

　　掌握常见的数据结构和实用算法；培养良好的编程习惯。

Java面向对象：封装、继承、多态等，面向对象程序设计，基础设计模式等。

　　掌握面向对象的基本原则以及在编程实践中的意义；掌握Java面向对象编程基本实现原理。

JDK核心API：语言核心包、异常处理、常用工具包、集合框架。

　　熟练掌握JDK核心API编程技术；理解API设计原则；具备熟练的阅读API文档的能力。

JavaSE核心：异常处理、多线程基础、IO系统、网络编程、Java反射机制、JVM性能调优（JVM内存结构剖析、GC分析及调优、JVM内存参数优化）、Java泛型、JDK新特性

　　熟练掌握JavaSE核心内容，特别是IO和多线程；初步具备面向对象设计和编程的能力；掌握基本的JVM优化策略。

SQL语言：SQL语句基础和提高、SQL语句调优。

　　熟练的掌握SQL语句；掌握一定的数据库查询技巧及SQL语句优化技巧。

Oracle数据库：Oracle体系结构及系统管理、Oracle数据库高级编程、数据库设计基础。

　　掌握Oracle体系结构及核心编程技术

XML：XML语法、XML解析（SAX、DOM）、Dom4j组件、Digester组件。

　　熟练掌握XML语法规则；理解DOM模型；熟悉Java对XML的各种解析方式。

HTML/CSS：TML基本文档结构、掌握CSS基础语法、关于HTML文档块、链接、列表、表格、表单等

　　掌握HTML基本原理；掌握CSS各种选择器及常见样式设置；熟练使用HTML常用元素。

JavaScript核心：JavaScript语言基础（数据类型、函数、对象、闭包）、Java DOM编程、事件模型、JavaScript面向对象编程。

　　深入理解JavaScript语言原理；熟练的使用JavaScript对HTML DOM进行编程；熟练掌握JavaScript对象对象封装技巧，为后续的JavaScript学习打下坚实的基础。

Servlet/JSP：Servlet生命周期及Servlet服务器、Tomcat部署配置、JSP语法、自定义标记、JSTL和EL表达式、JSP 新特性、Java Web 设计模式。

　　透彻理解Servlet核心原理；熟练掌握Servlet API；透彻理解JSP引擎工作原理；透彻理解标记库原理；熟悉常见的Java Web设计模式；为后续的Java Web开发打下坚实的理论基础。

Ajax：Ajax基础、XHR对象、Ajax设计模式、JSON技术。

　　掌握Ajax的基本通信原理；掌握基于XML和JSON的Ajax数据规则。

 二、课堂测试源代码

IUserDao.java

package com.jaovo.msg.dao;

import java.util.List;

import com.jaovo.msg.model.User;

public interface IUserDao {
public void add(User user);
public void delete(int id);
public void update(User user);
public User load(int id);
public User load(String username);
public List<User> load();

}

UserDaoImpl.java

package com.jaovo.msg.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.jaovo.msg.Util.DBUtil;
import com.jaovo.msg.Util.UserException;
import com.jaovo.msg.model.User;

import sun.net.www.content.text.plain;

public class UserDaoImpl implements IUserDao {

@Override
public void add(User user) {
//获得链接对象
Connection connection = DBUtil.getConnection();
//准备sql语句
String sql = "select count(*) from t_user where username = ?";
//创建语句传输对象
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, user.getUsername());
//接收结果集
resultSet = preparedStatement.executeQuery();
//遍历结果集
while(resultSet.next()) {
if (resultSet.getInt(1) > 0) {
throw new UserException("用户已存在") ;
}
}

sql = "insert into t_user(username,password) value (?,?)";
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, user.getUsername());
preparedStatement.setString(2, user.getPassword());
preparedStatement.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
//关闭资源
DBUtil.close(resultSet);
DBUtil.close(preparedStatement);
DBUtil.close(connection);
}

}

@Override
public void delete(int id) {
Connection connection = DBUtil.getConnection();
String sql = "delete from t_user where id = ?";
PreparedStatement preparedStatement = null;

try {
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1, id);
preparedStatement.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
DBUtil.close(preparedStatement);
DBUtil.close(connection);
}

}

@Override
public void update(User user) {
Connection connection = DBUtil.getConnection();
//准备sql语句
String sql = "update t_user set password = ? , nickname=? where id = ?";
//创建语句传输对象
PreparedStatement preparedStatement = null;
try {
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, user.getPassword());
preparedStatement.setInt(3, user.getId());
preparedStatement.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
DBUtil.close(preparedStatement);
DBUtil.close(connection);
}
}

@Override
public User load(int id) {
Connection connection = DBUtil.getConnection();
//准备sql语句
String sql = "select * from t_user where id = ?";
//创建语句传输对象
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
User user = null;
try {
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1, id);
resultSet = preparedStatement.executeQuery();
while(resultSet.next()) {
user = new User();
user.setId(id);
user.setUsername(resultSet.getString("username"));
user.setPassword(resultSet.getString("password"));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
DBUtil.close(resultSet);
DBUtil.close(preparedStatement);
DBUtil.close(connection);
}
return user;
}

@Override
public User load(String username) {
// TODO Auto-generated method stub
Connection connection = DBUtil.getConnection();
//准备sql语句
String sql = "select * from t_user where username = ?";
//创建语句传输对象
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
User user = null;
try {
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, username);
resultSet = preparedStatement.executeQuery();
while(resultSet.next()) {
user = new User();
user.setUsername(username);
user.setId(resultSet.getInt("username"));
user.setPassword(resultSet.getString("password"));
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
DBUtil.close(resultSet);
DBUtil.close(preparedStatement);
DBUtil.close(connection);
}
return user;

}

@Override
public List<User> load() {
Connection connection = DBUtil.getConnection();
//准备sql语句
String sql = "select * from t_user ";
//创建语句传输对象
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
//集合中只能放入user对象
List<User> users = new ArrayList<User>();
User user = null;
try {
preparedStatement = connection.prepareStatement(sql);
resultSet = preparedStatement.executeQuery();
while(resultSet.next()) {
user = new User();
user.setId(resultSet.getInt("id"));
user.setUsername(resultSet.getString("username"));
user.setPassword(resultSet.getString("password"));
users.add(user);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
DBUtil.close(resultSet);
DBUtil.close(preparedStatement);
DBUtil.close(connection);
}
return users;
}

}

User.java

package com.jaovo.msg.model;

public class User {

private int id;
private String username;
private String password;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}

}

DBUtil.java

package com.jaovo.msg.Util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DBUtil {

public static Connection getConnection() {
try {
//1 加载驱动
Class.forName("com.mysql.jdbc.Driver").newInstance();
} catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String user = "root";
String password = "a13293581799";
String url = "jdbc:mysql://localhost:3306/login";
Connection connection = null;
try {
//2 创建链接对象connection
connection = DriverManager.getConnection(url,user,password);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return connection;
}

//关闭资源的方法
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) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void close(ResultSet resultSet ) {
try {
if (resultSet != null) {
resultSet.close();
}

} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}

UserException.java

package com.jaovo.msg.Util;

public class UserException extends RuntimeException{

public UserException() {
super();
// TODO Auto-generated constructor stub
}

public UserException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
super(message, cause, enableSuppression, writableStackTrace);
// TODO Auto-generated constructor stub
}

public UserException(String message, Throwable cause) {
super(message, cause);
// TODO Auto-generated constructor stub
}

public UserException(String message) {
super(message);
// TODO Auto-generated constructor stub
}

public UserException(Throwable cause) {
super(cause);
// TODO Auto-generated constructor stub
}

}

indexcheck.jsp

<%@ page import="com.jaovo.msg.Util.DBUtil" language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ page import="com.jaovo.msg.model.User"%>>
<%@ page import="com.jaovo.msg.dao.UserDaoImpl"%>>
<!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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<%
request.setCharacterEncoding("UTF-8");
String username=(String)request.getParameter("username");
String password=(String)request.getParameter("password");//取出login.jsp的值
UserDaoImpl a=new UserDaoImpl();

User user=a.load(username);
String password1=user.getPassword();
if(password.equals(password1)){
response.sendRedirect("loginsuccess.jsp");
}
else{
out.print("<script language='javaScript'> alert('密码错误');</script>");
response.setHeader("refresh", "0;url=login.jsp");
}
%>
</body>
</html>

login.jsp

<%@ page import="java.sql.*" 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">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>登录界面</title>
</head>
<body>
<center>
<h1 style="color:red">登录</h1>
<form id="indexform" name="indexForm" action="indexcheck.jsp" method="post">
<table border="0">
<tr>
<td>账号：</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>密码：</td>
<td><input type="password" name="password">
</td>
</tr>
</table>
<br>
<input type="submit" value="登录" style="color:#BC8F8F">
</form>
<form action="zhuce.jsp">
<input type="submit" value="注册" style="color:#BC8F8F">
</form>
</center>
</body>
</html>

loginsuccess.jsp

<%@ page import="java.sql.*" 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">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<h1>登陆成功</h1>
</body>
</html>

运行结果截图：

四、课堂测试未按时完成的原因

实话实说，自己花在编程，学习上的时间都太少，导致现在没有自学过任何东西，数据库连接，jsp等等，都是我刚刚开始接触，所以刚开始写一个关于登陆界面，对于现在自己的水平，非常吃力。

五、目标及计划

接下来要花时间学习数据库操作的语句，jsp，html语言。