整個項目的整體結(jié)構(gòu)
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文件結(jié)構(gòu)
1. 首先創(chuàng)建一張數(shù)據(jù)表眷蚓，用于存儲用戶信息
create table tb_user(
id int(4) primary key auto_increment,
username varchar(50),
password varchar(50),
sex varchar(50),
question varchar(50),
answer varchar(50),
email varchar(50));
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2. JavaBean設(shè)計
- 實(shí)體類設(shè)計（放在entity包下面）
public class User {
private int id;
private String username;
private String password;
private String sex;
private String question;
private String answer;
private String email;
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;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getQuestion() {
return question;
}
public void setQuestion(String question) {
this.question = question;
}
public String getAnswer() {
return answer;
}
public void setAnswer(String answer) {
this.answer = answer;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}
2.數(shù)據(jù)庫連接工具類（放在util包下面）
public class DataBaseUtil {
//連接數(shù)據(jù)庫
public static Connection getConn() {
Connection conn = null;
try {
//加載數(shù)據(jù)庫驅(qū)動
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
String url = "jdbc:mysql://localhost:3306/jdbcdemo?useUnicode=true&characterEncoding=UTF-8";
try {
conn = DriverManager.getConnection(url, "root", "root");
if (conn != null) {
System.out.println(1123);
}
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
//關(guān)閉數(shù)據(jù)庫
public static void closeConn(Connection conn){
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
3.用戶數(shù)據(jù)庫操作
與用戶相關(guān)的數(shù)據(jù)庫操作方法被封裝到UserDao類中晴氨，實(shí)現(xiàn)數(shù)據(jù)的添加與查詢
public class UserDao {
//查詢數(shù)據(jù)庫信息
/**
* 在用戶提交注冊信息是毫捣，需要判斷該用戶名是否存在
*
* @param username
* @return
*/
public boolean userExist(String username) {
Connection conn = DataBaseUtil.getConn();
//根據(jù)指定的用戶名查詢信息
String sql = "select * from tb_user where username = ?";
try {
//獲取PreparedStatement對象，用于執(zhí)行數(shù)據(jù)庫查詢
PreparedStatement preparedStatement = conn.prepareStatement(sql);
preparedStatement.setString(1, username);
//執(zhí)行查詢獲取結(jié)果集
ResultSet resultSet = preparedStatement.executeQuery();
while (!resultSet.next()) {
//如果沒有此數(shù)據(jù)果复，證明該用戶名可用
return true;
}
//釋放資源,后創(chuàng)建的先銷毀
resultSet.close();
preparedStatement.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
DataBaseUtil.closeConn(conn);
}
return true;
}
/**
* 在用戶提交注冊信息時逻炊，如果注冊成功需要將秤掌，需要將用戶注冊的信息存入數(shù)據(jù)庫
*/
public void saveUser(User user) {
//獲取數(shù)據(jù)庫連接
Connection conn = DataBaseUtil.getConn();
//插入信息的sql語句
String sql = "insert into tb_user(username,password,sex,question,answer,email) values(?,?,?,?,?,?)";
try {
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, user.getUsername());
ps.setString(2, user.getPassword());
ps.setString(3, user.getSex());
ps.setString(4, user.getQuestion());
ps.setString(5, user.getAnswer());
ps.setString(6, user.getEmail());
//執(zhí)行更新操作
ps.executeUpdate();
//釋放資源
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
/**
* 注冊成功后，用戶既可通過注冊的用戶及密碼進(jìn)行登錄再来，對于程序而言蒙兰，此操作實(shí)質(zhì)是根據(jù)
* 用戶所提供的用戶名及密碼在數(shù)據(jù)庫進(jìn)行查詢，如果查詢成功其弊，則登錄成功
*/
public User login(String username, String password) {
//實(shí)例化一個用戶對象
User user =null;
Connection conn = DataBaseUtil.getConn();
String sql = "select * from tb_user where username = ? and password = ?";
try {
PreparedStatement ps = conn.prepareStatement(sql);
ps.setString(1, username);
ps.setString(2, password);
//執(zhí)行查詢獲取結(jié)果集
ResultSet rs = ps.executeQuery();
//判斷結(jié)果集是否有效,如過有效癞己，則對用戶進(jìn)行賦值
while (rs.next()) {
user = new User();
//對用戶對象進(jìn)行復(fù)制
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
user.setSex(rs.getString("sex"));
user.setQuestion(rs.getString("question"));
user.setAnswer(rs.getString("answer"));
user.setEmail(rs.getString("email"));
}
//釋放資源
rs.close();
ps.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
DataBaseUtil.closeConn(conn);
}
return user;
}
}
3.實(shí)現(xiàn)過程
- 用戶注冊
（1）創(chuàng)建RegServlet的類，用于處理用戶注冊請求的servlet
public class RegServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setContentType("text/html;charset=utf-8");
req.setCharacterEncoding("utf-8");
//獲取用戶注冊信息
String username = req.getParameter("username");
String password = req.getParameter("password");
String sex = req.getParameter("sex");
String question = req.getParameter("question");
String answer = req.getParameter("answer");
String email = req.getParameter("email");
//實(shí)例化UserDao對象
UserDao userDao = new UserDao();
if (username != null) {
//實(shí)例化一個User對象
User user = new User();
//對用戶對象的屬性賦值
user.setUsername(username);
user.setPassword(password);
user.setSex(sex);
user.setQuestion(question);
user.setAnswer(answer);
user.setEmail(email);
userDao.saveUser(user);
req.setAttribute("info", "注冊成功梭伐！ <br>");
} else {
req.setAttribute("info", "此用戶一存在痹雅！<br>");
}
//轉(zhuǎn)發(fā)到message.jsp頁面
req.getRequestDispatcher("message.jsp").forward(req, resp);
}
}
（2）創(chuàng)建注冊頁面
<%--
Created by IntelliJ IDEA.
User: pc
Date: 17-5-11
Time: 下午3:01
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>注冊界面</title>
</head>
<body>
<form action="/RegServlet" method="post" onsubmit="return reg(this)">
<table align="center" border="0" width="500">
<tr>
<td align="right" width="30%">用戶名：</td>
<td><input type="text" name="username" class="box"></td>
</tr>
<tr>
<td align="right" width="30%">密碼：</td>
<td><input type="password" name="password" class="box"></td>
</tr>
<tr>
<td align="right" width="30%">確認(rèn)密碼：</td>
<td><input type="password" name="password" class="box"></td>
</tr>
<tr>
<td align="right" width="30%">性別：</td>
<td>
<input type="radio" name="sex" value="男" checked="checked">男
<input type="radio" name="sex" value="女">女
</td>
</tr>
<tr>
<td align="right" width="30%">密碼找回問題：</td>
<td><input type="text" name="question" class="box"></td>
</tr>
<tr>
<td align="right" width="30%">密碼找回答案：</td>
<td><input type="text" name="answer" class="box"></td>
</tr>
<tr>
<td align="right" width="30%">郵箱：</td>
<td><input type="text" name="email" class="box"></td>
</tr>
<tr>
<td colspan="2" align="center" height="40">
<input type="submit" value="注冊">
<input type="reset" value="重置">
</td>
</tr>
</table>
</form>
</body>
</html>
用戶注冊界面
2.用戶登錄
（1）創(chuàng)建LoginServlet,處理用戶登錄請求的servlet.
/**
* Created by pc on 17-5-11.
*/
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setContentType("text/html;charset=utf-8");
req.setCharacterEncoding("utf-8");
String username = req.getParameter("username");
String password = req.getParameter("password");
UserDao userDao = new UserDao();
//根據(jù)密碼查詢用戶
User user = userDao.login(username, password);
//判斷user是否為空
if (user != null) {
//將用戶的對象放到session中
req.getSession().setAttribute("user", user);
//轉(zhuǎn)發(fā)到result.jsp頁面
req.getRequestDispatcher("message.jsp").forward(req, resp);
/**
response.sendRedirect(url)跳轉(zhuǎn)到指定的URL地址，產(chǎn)生一個新的request糊识，所以要傳遞參數(shù)只有在url后加參
數(shù)绩社，如：
url?id=1.
request.getRequestDispatcher(url).forward(request,response)是直接將請求轉(zhuǎn)發(fā)到指定URL，所以該請求
能夠直接獲得上一個請求的數(shù)據(jù)赂苗，也就是說采用請求轉(zhuǎn)發(fā)愉耙，request對象始終存在，不會重新創(chuàng)建拌滋。而
sendRedirect()會新建request對象朴沿，所以上一個request中的數(shù)據(jù)會丟失。
*/
}else {
//登錄失敗
req.setAttribute("info","用戶名或密碼錯誤败砂！");
req.getRequestDispatcher("message.jsp").forward(req, resp);
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
}
(2)創(chuàng)建用戶登錄的頁面
<%--
Created by IntelliJ IDEA.
User: pc
Date: 17-5-11
Time: 下午3:31
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登錄界面</title>
</head>
<body>
<form action="/LoginServlet" method="post" onsubmit="return login(this);">
<input type="text" name="username"><br>
<input type="password" name="password"><br>
<input type="submit" value="登錄">
<input type="reset" value="重置">
</form>
</body>
</html>
用戶登錄界面
3.用戶退出
創(chuàng)建UserExitServlet類赌渣，用來處理用戶推出請求
在處理過程中，需要將存放在session中的User清楚昌犹，達(dá)到用戶退出的效果
/**
* Created by pc on 17-5-11.
*/
public class UserExitServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
resp.setContentType("text/html;charset=utf-8");
//獲取session
HttpSession session = req.getSession();
//獲取用戶對象
User user = (User) session.getAttribute("user");
//判斷用戶是否有效
if (user != null) {
//將用戶對象逐出Session
session.removeAttribute("user");
//設(shè)置提示信息
req.setAttribute("info", user.getUsername() + "已成功退出坚芜！");
}
req.getRequestDispatcher("message.jsp").forward(req, resp);
}
}
4.提示頁面信息
程序在處理業(yè)務(wù)請求后，需要告知用戶處理結(jié)果斜姥，如用戶注冊成功鸿竖，用戶登錄失敗等信息，因此創(chuàng)建message.jsp頁面铸敏，用于顯示系統(tǒng)提示信息缚忧。
<%@ page import="model.User" %><%--
Created by IntelliJ IDEA.
User: pc
Date: 17-5-11
Time: 下午4:23
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>提示信息頁面</title>
</head>
<body>
<%
//獲取提示信息
String info = (String) request.getAttribute("info");
if (info != null) {
out.print(info);
}
/*獲取用戶的登錄信息*/
User user = (User) session.getAttribute("user");
if (user != null) {
%>
<table align="center" width="600" border="1" height="550" bordercolor="#E8F4CC">
<tr>
<td align="center" colspan="2">
<span style="font-weight: bold;font-size: 18px;"><%=user.getUsername()%></span>登錄成功！
</td>
</tr>
<tr>
<td align="center" colspan="2">性別：</td>
<td align="center" colspan="2"><%=user.getSex()%></td>
</tr>
<tr>
<td align="center" colspan="2">郵箱</td>
<td align="center" colspan="2"><%=user.getEmail()%></td>
</tr>
</table>
<%
}else {
out.print("<br>對不起您沒有登錄搞坝！");
}
%>
</body>
</html>
注冊
注冊成功
注冊的信息保存到數(shù)據(jù)庫
4. 一些容易混淆的知識點(diǎn)
-
session.setAttribute()和session.getAttribute()配對使用搔谴，作用域是整個會話期間，在所有的頁面都使用這些數(shù)據(jù)的時候使用桩撮。
-
request.setAttribute()和request.getAttribute()配對使用敦第，作用域是請求和被請求頁面之間峰弹。request.setAttribute()是只在此action的下一個forward需要使用的時候使用；request.getAttribute()表示從request范圍取得設(shè)置的屬性芜果，必須要先setAttribute設(shè)置屬性鞠呈，才能通過getAttribute來取得，設(shè)置與取得的為Object對象類型右钾。其實(shí)表單控件中的Object的name與value是存放在一個哈希表中的蚁吝，所以在這里給出Object的name會到哈希表中找出對應(yīng)它value。setAttribute()的參數(shù)是String和Object舀射。
-
request.getParameter()表示接收參數(shù)窘茁，參數(shù)為頁面提交的參數(shù)。包括：表單提交的參數(shù)脆烟、URL重寫(就是xxx?id=1中的id)傳的參數(shù)等山林，因此這個并沒有設(shè)置參數(shù)的方法(沒有setParameter())，而且接收參數(shù)返回的不是Object邢羔，而是String類型驼抹。
-
request.getParameter() 和request.getAttribute() 區(qū)別
#######（1）request.getParameter()取得是通過容器的實(shí)現(xiàn)來取得通過類似post，get等式傳入的數(shù)據(jù)拜鹤，request.setAttribute()和getAttribute()只是在web容器內(nèi)部流轉(zhuǎn)框冀，僅僅是請求處理階段。
#######（2）request.getParameter()方法傳遞的數(shù)據(jù)敏簿，會從Web客戶端傳到Web服務(wù)器端明也，代表HTTP請求數(shù)據(jù)。request.getParameter()方法返回String類型的數(shù)據(jù)惯裕。request.setAttribute()和getAttribute()方法傳遞的數(shù)據(jù)只會存在于Web容器內(nèi)部還有一點(diǎn)就是诡右，HttpServletRequest類有setAttribute()方法，而沒有setParameter()方法轻猖。
-
request.getAttribute()與request.setAttribute()
-
request.getAttribute("nameOfObj")可得到JSP頁面一表單中控件的Value。其實(shí)表單控件中的Object的name與value是存放在一個哈希表中的域那，所以在這里給出Object的name會到哈希表中找出對應(yīng)它的value咙边。而不同頁面間傳值使用request.setAttribute(position, nameOfObj)時，只會從a.jsp到b.jsp一次傳遞次员，之后這個request就會失去它的作用范圍败许，再傳就要再設(shè)一個request.setAttribute()。而使用session.setAttribute()會在一個過程中始終保有這個值淑蔚。
-
response.sendRedirect(url)與request.getRequestDispatcher(url).forward(request,response)的區(qū)別
- #######response.sendRedirect(url)跳轉(zhuǎn)到指定的URL地址市殷，產(chǎn)生一個新的request，所以要傳遞參數(shù)只有在url后加參數(shù)刹衫，如：url?id=1.
- #######request.getRequestDispatcher(url).forward(request,response)是直接將請求轉(zhuǎn)發(fā)到指定URL醋寝，所以該請求能夠直接獲得上一個請求的數(shù)據(jù)搞挣，也就是說采用請求轉(zhuǎn)發(fā)，request對象始終存在音羞，不會重新創(chuàng)建囱桨。而sendRedirect()會新建request對象，所以上一個request中的數(shù)據(jù)會丟失嗅绰。
