SERvet的表单 - 走看看

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SERvet的表单
首先要建立好数据库。

好了，先写好两个静态页面，分别负责登录和注册。

代码清单1：login.jsp（登录页面）
```
<%--
    Document   : login
    Created on : 2013-8-29, 17:14:30
    Author     : Barudisshu
--%>

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <title>登录</title>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    </head>
    <body>
        <div>
            <form action="login.do" method="post">
                <table>
                    <tr>
                        <td><label for="user">用户名：</label></td>
                        <td><input type="text" id="user" name="user" value=""></td>
                    </tr>
                    <tr>
                        <td><label for="password">密码：</label></td>
                        <td><input type="password" id="password" name="password" value=""></td>
                    </tr>
                    <tr>
                        <td colspan="2"><input type="submit" name="submit" value="登录"></td>
                    </tr>
                </table>
            </form>
        </div>
    </body>
</html>
```
代码清单2：register.jsp （注册页面）
```
<%--
    Document   : register
    Created on : 2013-8-29, 17:14:50
    Author     : Barudisshu
--%>

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>注册</title>
    </head>
    <body>
        <div>
            <form action="register.do" method="post">
                <table>
                    <tr>
                        <td><label for="user">用户名：</label></td>
                        <td><input type="text" id="user" name="user" value=""></td>
                    </tr>
                    <tr>
                        <td><label for="password">密码：</label></td>
                        <td><input type="password" id="password" name="password" value=""></td>
                    </tr>
                    <tr>
                        <td><label for="resure">确认密码：</label></td>
                        <td><input type="password" id="resure" name="resure" value=""></td>
                    </tr>
                    <tr>
                        <td><label for="email">邮箱地址：</label></td>
                        <td><input type="email" id="password" name="email" value=""></td>
                    </tr>
                    <tr>
                        <td colspan="2"><input type="submit" name="submit" value="注册"></td>
                    </tr>
                </table>
            </form>
        </div>
    </body>
</html>
```
建立数据库模型，主要实现数据库连接建立、执行查询、释放连接、判断等操作。

代码清单3：DataProvider.java （数据模型）
1. import java.sql.Connection;
2. import java.sql.DriverManager;
3. import java.sql.ResultSet;
4. import java.sql.SQLException;
5. import java.sql.Statement;
6. import java.util.logging.Level;
7. import java.util.logging.Logger;
9. /**
10. *
11. * @author Barudisshu
12. */
13. public class DataProvider {
15. //指定驱动名
16. protected static String driver = "com.mysql.jdbc.Driver";
17. //指定访问的URL
18. protected static String url = "jdbc:mysql://localhost:3306/gossip";
19. //MySQL用户名
20. protected static String user = "root";
21. //MySQL密码
22. protected static String password = "***";
23. //初始Connection
24. protected static Connection connection = null;
26. //建立连接
27. public static Connection getConnection() {
28. try {
29. Class.forName(driver);
30. connection = DriverManager.getConnection(url, user, password);
31. return connection;
32. } catch (ClassNotFoundException | SQLException e) {
33. return null;
34. }
35. }
37. //获取结果集
38. public static ResultSet getResultSet(String sql) {
39. Statement statement;
40. ResultSet resultSet = null;
41. Connection conn = getConnection();
42. if (conn != null) {
43. System.out.println("连接成功！");
44. try {
45. statement = conn.createStatement();
46. resultSet = statement.executeQuery(sql);
47. } catch (Exception e) {
48. }
49. return resultSet;
50. } else {
51. return null;
52. }
53. }
55. //判断结果集是否为空
56. public static boolean isResultSetNull(String sql) {
57. int count = 0;
58. ResultSet resultSet = getResultSet(sql);
59. try {
60. while (resultSet.next()) {
61. count += 1;
62. }
63. } catch (SQLException ex) {
64. Logger.getLogger(DataProvider.class.getName()).log(Level.SEVERE, null, ex);
65. }
66. if (count == 0) {
67. return true;
68. } else {
69. return false;
70. }
71. }
73. //是否执行
74. public static boolean execute(String sql) {
75. boolean success;
76. Statement statement;
77. Connection conn = getConnection();
78. if (conn != null) {
79. try {
80. statement = conn.createStatement();
81. success = statement.execute(sql);
82. } catch (Exception e) {
83. success = false;
84. }
85. } else {
86. success = false;
87. }
88. return success;
89. }
91. //释放连接
92. public static void releaseConnection() {
93. try {
94. if (connection != null) {
95. connection.close();
96. }
97. } catch (Exception e) {
98. }
99. }
100. }
创建注册验证Servlet，将取得请求参数、验证请求参数，业务跳转。逻辑业务部分。

代码清单4：Register.java （注册）
1. import java.io.IOException;
2. import java.util.ArrayList;
3. import java.util.List;
4. import javax.servlet.ServletException;
5. import javax.servlet.http.HttpServlet;
6. import javax.servlet.http.HttpServletRequest;
7. import javax.servlet.http.HttpServletResponse;
8. import net.individuals.mysql.data.DataProvider;
10. /**
11. *
12. * @author Barudisshu
13. */
14. public class RegisterServlet extends HttpServlet {
16. private final String SUCCESS_VIEW = "success.view";
17. private final String ERROR_VIEW = "error.view";
19. protected void processRequest(HttpServletRequest request, HttpServletResponse response)
20. throws ServletException, IOException {
21. response.setContentType("text/html;charset=UTF-8");
22. request.setCharacterEncoding("utf-8");
23. //获取请求参数
24. String email = request.getParameter("email");
25. String user = request.getParameter("user");
26. String password = request.getParameter("password");
27. String confirmedPasswd = request.getParameter("resure");
28. List<String> errors = new ArrayList<>();
29. if (isInvalidEmail(email)) {
30. errors.add("未填写邮件或邮件格式不正确");
31. }
32. if (isInvalidUsername(user)) {
33. errors.add("用户名为空或已存在");
34. }
35. if (isInvalidPassword(password, confirmedPasswd)) {
36. errors.add("请确认密码符合格式并再次确认密码");
37. }
38. String resultPage = ERROR_VIEW;
39. if (!errors.isEmpty()) {
40. request.setAttribute("errors", errors);
41. } else {
42. resultPage = SUCCESS_VIEW;
43. createUserData(email, user, password);
44. }
46. request.getRequestDispatcher(resultPage).forward(request, response);
47. }
49. //判断邮箱输入格式是否正确
50. private boolean isInvalidEmail(String email) {
51. return email == null || !email.matches("^[_a-z0-9-]+([.]"
52. + "[_a-z0-9-]+)*@[a-z0-9-]+([.][a-z0-9-]+)*$");
53. }
55. //判断是否存在该用户
56. private boolean isInvalidUsername(String username) {
57. return !DataProvider.isResultSetNull("select * from gossip.userinfo where username = '" + username + "'");
58. }
60. //判断密码是否有效
61. private boolean isInvalidPassword(String password, String confirmedPasswd) {
62. return password == null
63. || password.length() < 6
64. || password.length() > 16
65. || !password.equals(confirmedPasswd);
66. }
68. //创建用户资料并写入数据库
69. private void createUserData(String email, String username, String password) {
70. DataProvider.execute("insert into gossip.userinfo(email,username,password)"
71. + " values ('" + email + "','" + username + "','" + password + "')");
72. }
74. @Override
75. protected void doGet(HttpServletRequest request, HttpServletResponse response)
76. throws ServletException, IOException {
77. processRequest(request, response);
78. }
80. @Override
81. protected void doPost(HttpServletRequest request, HttpServletResponse response)
82. throws ServletException, IOException {
83. processRequest(request, response);
84. }
86. @Override
87. public String getServletInfo() {
88. return "Short description";
89. }// </editor-fold>
90. }
下面分别建立注册成功与失败的视图。

代码清单5：Error.java （注册失败）
```
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author Barudisshu
 */
public class Error extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<meta charset="utf-8">");
            out.println("<title>新增会员失败</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>新增会员失败</h1>");
            out.println("<ul style='color:red;'>");
            List<String> errors = (List<String>) request.getAttribute("errors");
            for (String error : errors) {
                out.println("<li>" + error + "</li>");
            }
            out.println("</ul>");
            out.println("<a href='register.html'>返回注册页面</a>");
            out.println("</body>");
            out.println("</html>");
        } finally {
            out.close();
        }
    }

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

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }
}
```
代码清单6：Success.java （注册成功）
1. import java.io.IOException;
2. import java.io.PrintWriter;
3. import javax.servlet.ServletException;
4. import javax.servlet.http.HttpServlet;
5. import javax.servlet.http.HttpServletRequest;
6. import javax.servlet.http.HttpServletResponse;
8. /**
9. *
10. * @author Barudisshu
11. */
12. public class Success extends HttpServlet {
14. protected void processRequest(HttpServletRequest request, HttpServletResponse response)
15. throws ServletException, IOException {
16. response.setContentType("text/html;charset=UTF-8");
17. try (PrintWriter out = response.getWriter()) {
18. /* TODO output your page here. You may use following sample code. */
19. out.println("<!DOCTYPE html>");
20. out.println("<html>");
21. out.println("<head>");
22. out.println("<meta charset="utf-8">");
23. out.println("<title>新增会员成功</title>");
24. out.println("</head>");
25. out.println("<body>");
26. out.println("<h1>会员" + request.getParameter("user") + "注册成功</h1>");
27. out.println("<a href="login.jsp">回首页登录");
28. out.println("</body>");
29. out.println("</html>");
30. }
31. }
33. @Override
34. protected void doGet(HttpServletRequest request, HttpServletResponse response)
35. throws ServletException, IOException {
36. processRequest(request, response);
37. }
39. @Override
40. protected void doPost(HttpServletRequest request, HttpServletResponse response)
41. throws ServletException, IOException {
42. processRequest(request, response);
43. }
44. }
注册成功后就可以登录了，登录需要进行相关验证操作。

代码清单7：Login.java （验证用户登录）
1. import java.io.IOException;
2. import javax.servlet.ServletException;
3. import javax.servlet.http.HttpServlet;
4. import javax.servlet.http.HttpServletRequest;
5. import javax.servlet.http.HttpServletResponse;
6. import net.individuals.mysql.data.DataProvider;
8. /**
9. *
10. * @author Barudisshu
11. */
12. public class LoginServlet extends HttpServlet {
14. private final String SUCCESS_VIEW = "member.view";
15. private final String ERROR_VIEW = "login.jsp";
17. protected void processRequest(HttpServletRequest request, HttpServletResponse response)
18. throws ServletException, IOException {
19. response.setContentType("text/html;charset=UTF-8");
20. request.setCharacterEncoding("utf-8");
21. String user = request.getParameter("user");
22. String password = request.getParameter("password");
23. if(checkLogin(user, password)){
24. request.getRequestDispatcher(SUCCESS_VIEW).forward(request, response);
25. }else{
26. response.sendRedirect(ERROR_VIEW);
27. }
29. }
31. //读取数据库，验证登录
32. private boolean checkLogin(String username, String password) {
33. if (username != null && password != null) {
34. return !DataProvider.isResultSetNull("select * from gossip.userinfo "
35. + "where username = '" + username + "' and password = '" + password + "'");
36. }
37. return false;
38. }
40. @Override
41. protected void doGet(HttpServletRequest request, HttpServletResponse response)
42. throws ServletException, IOException {
43. processRequest(request, response);
44. }
46. @Override
47. protected void doPost(HttpServletRequest request, HttpServletResponse response)
48. throws ServletException, IOException {
49. processRequest(request, response);
50. }
51. }
验证失败，则从新登录，通过sendRedirect()跳转到登录页面；验证成功，则进行下一步操作。

代码清单8：Member.java （登录成功）
1. import java.io.IOException;
2. import java.io.PrintWriter;
3. import javax.servlet.ServletException;
4. import javax.servlet.http.HttpServlet;
5. import javax.servlet.http.HttpServletRequest;
6. import javax.servlet.http.HttpServletResponse;
8. /**
9. *
10. * @author Barudisshu
11. */
12. public class Member extends HttpServlet {
14. protected void processRequest(HttpServletRequest request, HttpServletResponse response)
15. throws ServletException, IOException {
16. response.setContentType("text/html;charset=UTF-8");
17. PrintWriter out = response.getWriter();
18. try {
19. /* TODO output your page here. You may use following sample code. */
20. out.println("<!DOCTYPE html>");
21. out.println("<html>");
22. out.println("<head>");
23. out.println("<meta charset="utf-8">");
24. out.println("<title>会员登录成功页面</title>");
25. out.println("</head>");
26. out.println("<body>");
27. out.println("<h1>会员 " + request.getParameter("user") + " 你好</h1>");
28. out.println("</body>");
29. out.println("</html>");
30. } finally {
31. out.close();
32. }
33. }
35. @Override
36. protected void doGet(HttpServletRequest request, HttpServletResponse response)
37. throws ServletException, IOException {
38. processRequest(request, response);
39. }
41. @Override
42. protected void doPost(HttpServletRequest request, HttpServletResponse response)
43. throws ServletException, IOException {
44. processRequest(request, response);
45. }
46. }
代码清单9：web.xml （标准依赖部署文件）
```
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>net.individuals.web.servlet.LoginServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>RegisterServlet</servlet-name>
        <servlet-class>net.individuals.web.servlet.RegisterServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>Error</servlet-name>
        <servlet-class>net.individuals.web.servlet.Error</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>Success</servlet-name>
        <servlet-class>net.individuals.web.servlet.Success</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>Member</servlet-name>
        <servlet-class>net.individuals.web.servlet.Member</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/login.do</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>RegisterServlet</servlet-name>
        <url-pattern>/register.do</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Error</servlet-name>
        <url-pattern>/error.view</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Success</servlet-name>
        <url-pattern>/success.view</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Member</servlet-name>
        <url-pattern>/member.view</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
</web-app>
```
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原文地址：https://www.cnblogs.com/yangshuyuan1009/p/10193489.html