JDBC操作数据库之查询数据
时间：2021-07-01 10:21:17
帮助过：4人阅读
package com.lyq.bean;
2 import java.io.IOException;
3 import java.sql.Connection;
4 import java.sql.DriverManager;
5 import java.sql.ResultSet;
6 import java.sql.SQLException;
7 import java.sql.Statement;
8 import java.util.ArrayList;
9 import java.util.List;
10 import javax.servlet.ServletException;
11 import javax.servlet.http.HttpServlet;
12 import javax.servlet.http.HttpServletRequest;
13 import javax.servlet.http.HttpServletResponse;
14 public class FindServlet
extends HttpServlet {
15 private static final long serialVersionUID = 1L
;
16
17 protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
18 try {
19 // 加载数据库驱动，注册到驱动管理器
20 Class.forName("com.mysql.jdbc.Driver"
);
21 // 数据库连接字符串
22 String url = "jdbc:mysql://localhost:3306/db_database10"
;
23 // 数据库用户名
24 String username = "root"
;
25 // 数据库密码
26 String password = "111"
;
27 // 创建Connection连接
28 Connection conn =
DriverManager.getConnection(url,username,password);
29 // 获取Statement
30 Statement stmt =
conn.createStatement();
31 // 添加图书信息的SQL语句
32 String sql = "select * from tb_books"
;
33 // 执行查询
34 ResultSet rs =
stmt.executeQuery(sql);
35 // 实例化List对象
36 List<Book> list =
new ArrayList<Book>
();
37 // 判断光标向后移动，并判断是否有效
38 while(rs.next()){
39 // 实例化Book对象
40 Book book =
new Book();
41 // 对id属性赋值
42 book.setId(rs.getInt("id"
));
43 // 对name属性赋值
44 book.setName(rs.getString("name"
));
45 // 对price属性赋值
46 book.setPrice(rs.getDouble("price"
));
47 // 对bookCount属性赋值
48 book.setBookCount(rs.getInt("bookCount"
));
49 // 对author属性赋值
50 book.setAuthor(rs.getString("author"
));
51 // 将图书对象添加到集合中
52 list.add(book);
53 }
54 // 将图书集合放置到request之中
55 request.setAttribute("list"
, list);
56 rs.close();
// 关闭ResultSet
57 stmt.close();
// 关闭Statement
58 conn.close();
// 关闭Connection
59 }
catch (ClassNotFoundException e) {
60 e.printStackTrace();
61 }
catch (SQLException e) {
62 e.printStackTrace();
63 }
64 // 请求转发到book_list.jsp request.getRequestDispatcher("book_list.jsp").forward(request, response);
65 }
66 }
（3）图书信息展示页面book_list.jsp代码
1 <%@ page language="java" contentType="text/html; charset=UTF-8"
2 pageEncoding="UTF-8"%>
3 <%@ page import="java.util.List" %>
4 <%@ page import="com.java.Book" %>
5 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
6 <html>
7 <head>
8 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
9 <title>查看所有图书</title>
10 <style type="text/css">
11 h2{
12 margin:0px;
13 }
14 div,td{
15 font-size:12px;
16 }
17 </style>
18 </head>
19 <body>
20 <div style="text-align:center;">
21 <table width="45px" border="1px" height="180px">
22 <tr bgcolor="white">
23 <td colspan="4">
24 <h2>所有图书信息</h2>
25 </td>
26 </tr>
27 <tr bgcolor="#e1ffc1">
28 <td><b>图书名称</b></td>
29 <td><b>图书价格</b></td>
30 <td><b>图书数量</b></td>
31 <td><b>图书作者</b></td>
32 </tr>
33 <%
34 //获取图书信息集合
35 List<Book> list = (List<Book>)request.getAttribute("list");
36 //判断集合是否有效
37 if(list == null || list.size() < 1){
38 out.print("没有数据");
39 }else{
40 //遍历图书集合中的数据
41 for(Book book:list){
42 %>
43 <tr bgcolor="white">
44 <td><%= book.getName() %></td>
45 <td><%= book.getPrice() %></td>
46 <td><%= book.getBookcout() %></td>
47 <td><%= book.getAuthor() %></td>
48 </tr>
49 <%
50 }
51 }
52 %>
53 </table>
54 </div>
55 </body>
56 </html>
（4）最后web.xml中Servlet的配置信息为：
1 <servlet>
2 <servlet-name>FindServlet</servlet-name>
3 <servlet-class>com.java.FindServlet</servlet-class>
4 </servlet>
5 <servlet-mapping>
6 <servlet-name>FindServlet</servlet-name>
7 <url-pattern>/FindServlet</url-pattern>
8 </servlet-mapping>
JDBC操作数据库之查询数据
标签：html4 manage col content table version tps back log
