|--要求
|--实现方式：
1、前台使用使用函数检测输入内容，并使用jQuery的ajax异步将检测到的内容发送到后台对比
2、如果输入内容在数据库内已经存在，就提醒已经存在
|--代码
1 package cn.exercise.dao;
2
3 import cn.exercise.util.ConfigManager;
4
5 import java.sql.*;
6
7 public class BaseDao {
8 //引入ps对象，conn对象，rs对象
9 private PreparedStatement ps = null;
10 private Connection conn = null;
11 private ResultSet rs = null;
12
13 //引入连接数据库需要的配置信息
14 public final String driver = ConfigManager.getInstance().getString("jdbc.driver");
15 public final String url = ConfigManager.getInstance().getString("jdbc.url");
16 public final String user = ConfigManager.getInstance().getString("jdbc.userName");
17 public final String pwd = ConfigManager.getInstance().getString("jdbc.password");
18
19 /**
20 * 获取数据库连接
21 *
22 * @return
23 */
24 public Connection getConn() {
25 try {
26 Class.forName(driver);
27 conn = DriverManager.getConnection(url, user, pwd);
28 } catch (ClassNotFoundException e) {
29 e.printStackTrace();
30 } catch (SQLException e) {
31 e.printStackTrace();
32 }
33 return conn;
34 }
35
36 /**
37 * 查询方法
38 *
39 * @param sql
40 * @param obj
41 * @return
42 */
43 public ResultSet executeQuery(String sql, Object... obj) {
44 getConn();
45 try {
46 ps = conn.prepareStatement(sql);
47 for (int i = 0; i < obj.length; i++) {
48 ps.setObject((i + 1), obj[i]);
49 }
50 rs = ps.executeQuery();
51 } catch (SQLException e) {
52 e.printStackTrace();
53 }
54 return rs;
55 }
56
57
58 /**
59 * 更新数据库的方法
60 *
61 * @param sql
62 * @param obj
63 * @return
64 */
65 public int executeUpdate(String sql, Object... obj) {
66 getConn();
67 int result = 0;
68 try {
69 ps = conn.prepareStatement(sql);
70 for (int i = 0; i < obj.length; i++) {
71 ps.setObject((i + 1), i);
72 }
73 result = ps.executeUpdate();
74 } catch (SQLException e) {
75 e.printStackTrace();
76 }
77
78 return result;
79 }
80
81 public void closeAll() {
82 try {
83 if (rs != null) {
84 rs.close();
85 }
86 if (ps != null) {
87 ps.close();
88 }
89 if (conn != null) {
90 conn.close();
91 }
92 } catch (SQLException e) {
93 e.printStackTrace();
94 }
95 }
96
97
98
99 }
BaseDao--访问数据库的基类
1 package cn.exercise.dao;
2
3 import cn.exercise.pojo.JsonAnalysis;
4 import cn.exercise.pojo.User;
5 import com.sun.org.apache.xpath.internal.objects.XObject;
6
7 import java.sql.ResultSet;
8 import java.sql.SQLException;
9
10 public class UserDaoImpl extends BaseDao implements UserDao {
11 ResultSet rs = null;
12 JsonAnalysis jsonAnalysis = null;
13
14 @Override
15 public JsonAnalysis getUserByEmail(String uemail) {
16 //SELECT * from jsonanalysis WHERE uemail=?
17 String sql = "SELECT * from jsonanalysis WHERE uemail=?";
18 Object obj = (Object) uemail;
19 rs = executeQuery(sql, uemail);
20 // System.out.println(rs);
21
22 try {
23 if (rs.next()) {
24 jsonAnalysis = new JsonAnalysis();
25 // System.out.println(rs.getInt("uid")+rs.getString("uname")+rs.getString("uemail"));
26 jsonAnalysis.setUid(rs.getInt("uid"));
27 jsonAnalysis.setUname(rs.getString("uname"));
28 jsonAnalysis.setUemail(rs.getString("uemail"));
29 }
30 } catch (SQLException e) {
31 e.printStackTrace();
32 }
33 // System.out.println(jsonAnalysis);
34 return jsonAnalysis;
35 }
36
37
38 // public static void main(String[] args) {
39 // UserDao user = new UserDaoImpl();
40 // System.out.println(user.getUserByEmail("[email protected]"));
41 // }
42 }
实体类Dao ---负责具体查询
1 package cn.exercise.service;
2
3 import cn.exercise.dao.UserDao;
4 import cn.exercise.dao.UserDaoImpl;
5 import cn.exercise.pojo.JsonAnalysis;
6
7 public class JsonAnalysisServiceImpl implements JsonAnalysisService {
8 @Override
9 public boolean existByEmail(String uemail) {
10 boolean flag = false;
11 UserDao userDao = new UserDaoImpl();
12 JsonAnalysis user = userDao.getUserByEmail(uemail);
13 if (user != null) {
14 flag = true;
15 } else {
16 flag = false;
17 }
18 return flag;
19 }
20
21 // public static void main(String[] args) {
22 // JsonAnalysisServiceImpl j=new JsonAnalysisServiceImpl();
23 // System.out.println(j.existByEmail("[email protected]"));
24 // }
25 }
业务层的实现类---用于判定是否查到了信息
1 package cn.exercise.web.serlet;
2
3 import cn.exercise.service.JsonAnalysisServiceImpl;
4
5 import javax.servlet.ServletException;
6 import javax.servlet.annotation.WebServlet;
7 import javax.servlet.http.HttpServlet;
8 import javax.servlet.http.HttpServletRequest;
9 import javax.servlet.http.HttpServletResponse;
10 import java.io.IOException;
11 import java.io.PrintWriter;
12
13 //@WebServlet(name = "AjaxServlet", urlPatterns = "/email")
14 @WebServlet("/email")
15 public class AjaxServlet extends HttpServlet {
16 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
17 // this.doGet(request, response);
18 doGet(request, response);
19 }
20
21 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
22 System.out.println("测试是否有接到请求");
23 response.setContentType("text/html;charset=UTF-8");
24 String uemail = request.getParameter("uemail");
25 String uname = request.getParameter("uname");
26 String pwd = request.getParameter("pwd");
27 JsonAnalysisServiceImpl jasi = new JsonAnalysisServiceImpl();
28
29 String reback = "";
30 if (jasi.existByEmail(uemail)) {
31 reback = "该邮箱已经注册,请换个邮箱注册";
32 } else {
33 reback = "该邮箱未注册，可以使用";
34 }
35 PrintWriter writer = response.getWriter();
36 writer.println(reback);
37 }
38 }
Servlet类---负责控制业务
前端
1 <%--
2 Created by IntelliJ IDEA.
3 User: Administrator
4 Date: 2019/10/17
5 Time: 9:09
6 To change this template use File | Settings | File Templates.
7 --%>
8 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
9 <html>
10 <head>
11 <title>邮箱验证</title>
12 <script src="js/jquery-1.12.4.js"></script>
13 <script>
14 function test() {
15 var a = document.getElementById("input").value;
16 // alert(a);
17 $.ajax({
18 "url": "email",
19 "type": "get",
20 "data": "uemail="+a,
21 "dataType":"text",
22 "success":function (data) {
23 document.getElementById("a").innerText=data;
24 },
25 "error":function () {
26 alert("请联系管理员");
27 }
28 })
29 }
30 </script>
31 </head>
32 <body>
33 <form action="/email" method="get">
34 <table>
35 <tr>
36 <td>注册邮箱：</td>
37 <td><input type="email" name="uemail" onblur="test()" id="input"></td>
38 <td id="a">*</td>
39 </tr>
40 <tr>
41 <td>用 户 名：</td>
42 <td><input type="text" name="uname"></td>
43 <td>*</td>
44 </tr>
45 <tr>
46 <td>密 码：</td>
47 <td><input type="text" name="pwd"></td>
48 <td>*</td>
49 </tr>
50 <tr align="center">
51 <td colspan="3"><input type="submit" value="提交"></td>
52 </tr>
53 </table>
54 </form>
55
56 </body>
57 </html>
Jsp--负责展示效果
|--过程中的错误
1、jsp访问servlet路径不对-----将jsp从一个目录里面取出来之后OK
2、resources文件夹没能被JDBC的ConfigManager读取到----右击resources文件夹，选择Make directory as --> resuorce root
3、servlet命名不规范，将"/email.do"写成“/Email.do”之后，服务器报错
4、将过滤器设置成了Servlet......导致服务器无法运行
原文地址：https://www.cnblogs.com/twuxian/p/11695538.html
时间： 2024-10-13 14:35:19