jsp+servlet+jdbc实现对数据库的增删改查

来源：互联网收集：自由互联发布时间：2021-06-25

一、JSP和Servlet的简单介绍 1、Servlet和JSP简介： Java开发Web应用程序时用到的技术主要有两种，即Servlet和JSP，Servlet是在服务器端执行的Java程序，一个被称为Servlet容器的程序（其实就是服

一、JSP和Servlet的简单介绍

1、Servlet和JSP简介：

Java开发Web应用程序时用到的技术主要有两种，即Servlet和JSP，Servlet是在服务器端执行的Java程序，一个被称为Servlet容器的程序（其实就是服务器）负责执行Java程序，而JSP(Java Server Page)则是一个页面，由JSP容器负责执行.

2、Servlet和JSP的区别：

Servlet以Java程序为主，输出HTML代码时需要使用out.println函数，也就是说Java中内嵌HTML；而JSP则以HTML页面为主，需要写Java代码时则在页面中直接插入Java代码，即HTML中内嵌Java.

3、MVC模型

MVC模型就是将数据、逻辑处理、用户界面分离的一种方法
1）、M(Model, 模型)：用于数据处理、逻辑处理
2）、V(View，视图)：用于显示用户界面
3）、C(Controller，控制器)：根据客户端的请求控制逻辑走向和画面

而在Java中，MVC这三个部分则分别对应于 JavaBeans、JSP和Servlet
1）、M = JavaBeans：用于传递数据，拥有与数据相关的逻辑处理
2）、V = JSP：从Model接收数据并生成HTML
3）、C = Servlet：接收HTTP请求并控制Model和View

4、jdbc连接，可参考文章：点击打开链接

二、代码演示，实现了book的添加删除和修改功能

1、环境的配置

myeclipse+tomcat+mysql

2、Book中bean类

[java] view plain copy

package example.bean.book;
public class Book {
// 编号
private int id;
// 图书名称
private String name;
// 价格
private double price;
// 数量
private int bookCount;
// 作者
private String author;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public int getBookCount() {
return bookCount;
}
public void setBookCount(int bookCount) {
this.bookCount = bookCount;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
}

3、Servlet类

1)、FindServlet.java

[java] view plain copy

package example.servlet.book;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import example.bean.book.Book;
/**
* Servlet implementation class FindServlet
*/
public class FindServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
try {
// 加载数据库驱动，注册到驱动管理器
Class.forName("com.mysql.jdbc.Driver");
// 数据库连接字符串
String url = "jdbc:mysql://localhost:3306/db_book?useUnicode=true&characterEncoding=utf-8";
// 数据库用户名
String username = "root";
// 数据库密码
String password = "";
// 创建Connection连接
Connection conn = DriverManager.getConnection(url, username,
password);
// 添加图书信息的SQL语句
String sql = "select * from tb_books";
// 获取Statement
Statement statement = conn.createStatement();
ResultSet resultSet = statement.executeQuery(sql);
List<Book> list = new ArrayList<Book>();
while (resultSet.next()) {
Book book = new Book();
book.setId(resultSet.getInt("id"));
book.setName(resultSet.getString("name"));
book.setPrice(resultSet.getDouble("price"));
book.setBookCount(resultSet.getInt("bookCount"));
book.setAuthor(resultSet.getString("author"));
list.add(book);
}
request.setAttribute("list", list);
resultSet.close();
statement.close();
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
request.getRequestDispatcher("book_list.jsp")
.forward(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}

2)、UpdateServlet.java类

[java] view plain copy

package example.servlet.book;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class UpdateServlet
*/
public class UpdateServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
int id = Integer.valueOf(request.getParameter("id"));
int bookCount = Integer.valueOf(request.getParameter("bookCount"));
try {
// 加载数据库驱动，注册到驱动管理器
Class.forName("com.mysql.jdbc.Driver");
// 数据库连接字符串
String url = "jdbc:mysql://localhost:3306/db_book";
// 数据库用户名
String username = "root";
// 数据库密码
String password = "";
// 创建Connection连接
Connection conn = DriverManager.getConnection(url, username,
password);
// 更新SQL语句
String sql = "update tb_books set bookcount=? where id=?";
// 获取PreparedStatement
PreparedStatement ps = conn.prepareStatement(sql);
// 对SQL语句中的第一个参数赋值
ps.setInt(1, bookCount);
// 对SQL语句中的第二个参数赋值
ps.setInt(2, id);
// 执行更新操作
ps.executeUpdate();
// 关闭PreparedStatement
ps.close();
// 关闭Connection
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
// 重定向到FindServlet
response.sendRedirect("FindServlet");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}

3）、DeleteServlet类
[java] view plain copy

package example.servlet.book;
import java.io.IOException;
import java.sql.Connection;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import example.dao.book.BookJdbcDao;
import example.dao.book.ConnectionFactory;
/**
* Servlet implementation class DeleteServlet
*/
public class DeleteServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
int id = Integer.valueOf(request.getParameter("id"));
try {
// // 加载数据库驱动，注册到驱动管理器
// Class.forName("com.mysql.jdbc.Driver");
// // 数据库连接字符串
// String url = "jdbc:mysql://localhost:3306/db_book";
// // 数据库用户名
// String username = "root";
// // 数据库密码
// String password = "";
// // 创建Connection连接
// Connection conn = DriverManager.getConnection(url, username,
// password);
// // 删除图书信息的SQL语句
// String sql = "delete from tb_books where id=?";
// // 获取PreparedStatement
// PreparedStatement ps = conn.prepareStatement(sql);
// // 对SQL语句中的第一个占位符赋值
// ps.setInt(1, id);
// // 执行更新操作
// ps.executeUpdate();
// // 关闭PreparedStatement
// ps.close();
// // 关闭Connection
// conn.close();
BookJdbcDao bookDao=new BookJdbcDao();
Connection conn=ConnectionFactory.getInstance().getConnection();
bookDao.delete(conn,id);
} catch (Exception e) {
e.printStackTrace();
}
// 重定向到FindServlet
response.sendRedirect("FindServlet");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}

4、servlet访问url映射配置：

由于客户端是通过URL地址访问web服务器中的资源，所以Servlet程序若想被外界访问，必须把servlet程序映射到一个URL地址上，这个工作在web.xml文件中使用<servlet>元素和<servlet-mapping>元素完成，<servlet>元素用于注册Servlet，它包含有两个主要的子元素：<servlet-name>和<servlet-class>，分别用于设置Servlet的注册名称和Servlet的完整类名。一个<servlet-mapping>元素用于映射一个已注册的Servlet的一个对外访问路径，它包含有两个子元素：<servlet-name>和<url-pattern>，分别用于指定Servlet的注册名称和Servlet的对外访问路径.另外：同一个Servlet可以被映射到多个URL上，即多个<servlet-mapping>元素的<servlet-name>子元素的设置值可以是同一个Servlet的注册名.

eg:上例中的web.xml

[html] view plain copy

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>JdbcConnection</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description></description>
<display-name>FindServlet</display-name>
<servlet-name>FindServlet</servlet-name>
<servlet-class>example.servlet.book.FindServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>FindServlet</servlet-name>
<url-pattern>/FindServlet</url-pattern>
</servlet-mapping>
<servlet>
<description></description>
<display-name>UpdateServlet</display-name>
<servlet-name>UpdateServlet</servlet-name>
<servlet-class>example.servlet.book.UpdateServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UpdateServlet</servlet-name>
<url-pattern>/UpdateServlet</url-pattern>
</servlet-mapping>
<servlet>
<description></description>
<display-name>DeleteServlet</display-name>
<servlet-name>DeleteServlet</servlet-name>
<servlet-class>example.servlet.book.DeleteServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DeleteServlet</servlet-name>
<url-pattern>/DeleteServlet</url-pattern>
</servlet-mapping>
</web-app>

5、jsp页面

1）、index.jsp web页面主界面

[html] view plain copy

<%@page import="java.sql.SQLException"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.Connection"%>
<%@ page 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>添加图书信息</title>
<script type="text/javascript">
function check(form) {
with (form) {
if (name.value == "") {
alert("图书名称不能为空");
return false;
}
if (price.value == "") {
alert("图书价格不能为空");
return false;
}
if (author.value == "") {
alert("作者不能为空");
return false;
}
}
}
</script>
</head>
<body>
<form action="addbook.jsp" method="post" onsubmit="check(this)">
<table align="center" width="450">
<tr>
<td align="center" colspan="2">
<h2>添加图书信息</h2>
<hr>
</td>
</tr>
<tr>
<td align="right">图书名称：</td>
<td><input type="text" name="name"></td>
</tr>
<tr>
<td align="right">价格：</td>
<td><input type="text" name="price"></td>
</tr>
<tr>
<td align="right">数量：</td>
<td><input type="text" name="bookCount" /></td>
</tr>
<tr>
<td align="right">作者：</td>
<td><input type="text" name="author" /></td>
</tr>
<tr>
<td align="center" colspan="2"><input type="submit" value="添　加">
</td>
</tr>
</table>
</form>
<h2 align="center">
<a href="FindServlet">查询图书信息</a>
</h2>
</body>
</html>

2)、addbook.jsp 添加书籍成功或者失败后的显示页面

[html] view plain copy

<%@ page 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">
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.PreparedStatement"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>添加结果</title>
</head>
<body>
<%
request.setCharacterEncoding("utf-8");
%>
<jsp:useBean id="book" class="example.bean.book.Book"></jsp:useBean>
<jsp:setProperty property="*" name="book" />
<%
try {
// 加载数据库驱动，注册到驱动管理器
Class.forName("com.mysql.jdbc.Driver");
// 数据库连接字符串
String url = "jdbc:mysql://localhost:3306/db_book?useUnicode=true&characterEncoding=utf-8";
// 数据库用户名
String username = "root";
// 数据库密码
String password = "";
// 创建Connection连接
Connection conn = DriverManager.getConnection(url, username,
password);
// 添加图书信息的SQL语句
String sql = "insert into tb_books(name,price,bookCount,author) values(?,?,?,?)";
// 获取PreparedStatement
PreparedStatement ps = conn.prepareStatement(sql);
// 对SQL语句中的第1个参数赋值
ps.setString(1, book.getName());
// 对SQL语句中的第2个参数赋值
ps.setDouble(2, book.getPrice());
// 对SQL语句中的第3个参数赋值
ps.setInt(3, book.getBookCount());
// 对SQL语句中的第4个参数赋值
ps.setString(4, book.getAuthor());
// 执行更新操作，返回所影响的行数
int row = ps.executeUpdate();
// 判断是否更新成功
if (row > 0) {
// 更新成输出信息
out.print("成功添加了 " + row + "条数据！");
}
// 关闭PreparedStatement，释放资源
ps.close();
// 关闭Connection，释放资源
conn.close();
} catch (Exception e) {
out.print("图书信息添加失败！");
e.printStackTrace();
}
%>
<br>
<a href="index.jsp">返回</a>
</body>
</html>

3)、book_list.jsp 查找所有书籍信息的显示页面，以表格方式显示

[html] view plain copy

<%@ page 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">
<%@page import="java.util.List"%>
<%@page import="example.bean.book.Book"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>所有图书信息</title>
<style type="text/css">
td {
font-size: 12px;
}
h2 {
margin: 0px
}
</style>
<script type="text/javascript">
function check(form) {
with (form) {
if (bookCount.value == "") {
alert("请输入更新数量！");
return false;
}
if (isNaN(bookCount.value)) {
alert("格式错误！");
return false;
}
return true;
}
}
</script>
</head>
<body>
<table align="center" width="450" border="1" height="180"
bordercolor="white" bgcolor="black" cellpadding="1" cellspacing="1">
<tr bgcolor="white">
<td align="center" colspan="7">
<h2>所有图书信息</h2>
</td>
</tr>
<tr align="center" bgcolor="#e1ffc1">
<td><b>ID</b></td>
<td><b>图书名称</b></td>
<td><b>价格</b></td>
<td><b>数量</b></td>
<td><b>作者</b></td>
<td><b>修改</b></td>
<td><b>删除</b></td>
</tr>
<%
// 获取图书信息集合
List<Book> list = (List<Book>) request.getAttribute("list");
// 判断集合是否有效
if (list == null || list.size() < 1) {
out.print("没有数据！");
} else {
// 遍历图书集合中的数据
for (Book book : list) {
%>
<tr align="center" bgcolor="white">
<td><%=book.getId()%></td>
<td><%=book.getName()%></td>
<td><%=book.getPrice()%></td>
<td><%=book.getBookCount()%></td>
<td><%=book.getAuthor()%></td>
<td >
<form style="align:center; background-color: gray" action="UpdateServlet" method="post"
onsubmit="return check(this);">
<input type="hidden" name="id" value="<%=book.getId()%>"> <input
type="text" name="bookCount" size="3">
<input type="submit" value="修改数量">
</form>
</td>
<td>
<a href="DeleteServlet?id=<%=book.getId()%>">删除</a>
</td>
</tr>
<%
}
}
%>
</table>
<h2 align="center">
<a href="index.jsp">返回添加图书信息页面</a>
</h2>
</body>
</html>

6、jdbc简单的封装

1）、ConnectionFactory.java工厂类

[java] view plain copy

package example.dao.book;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class ConnectionFactory {
private String driverClassName = "com.mysql.jdbc.Driver";
private String url = "jdbc:mysql://localhost:3306/db_book?useUnicode=true&characterEncoding=utf-8";
private String userName = "root";
private String password = "";
private static ConnectionFactory connectionFactory=null;
private ConnectionFactory() {
try {
Class.forName(driverClassName);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public Connection getConnection() throws SQLException
{
return DriverManager.getConnection(url, userName, password);
}
public static ConnectionFactory getInstance()
{
if (null==connectionFactory) {
connectionFactory=new ConnectionFactory();
}
return connectionFactory;
}
}

2）、BookJdbcDao.java数据库操作封装类

[java] view plain copy

package example.dao.book;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import example.bean.book.Book;
public class BookJdbcDao {
private PreparedStatement ptmt = null;
private ResultSet rs = null;
public BookJdbcDao() {
}
public void findAll(Connection conn) throws SQLException
{
//to do
}
public void delete(Connection conn, int id) throws SQLException
{
String sql = "delete from tb_books where id=?";
try{
ptmt = conn.prepareStatement(sql);
// 对SQL语句中的第一个占位符赋值
ptmt.setInt(1, id);
// 执行更新操作
ptmt.executeUpdate();
}finally{
if (null!=ptmt) {
ptmt.close();
}
if (null!=conn) {
conn.close();
}
}
}
public void update(Connection conn, int id ,int bookcount) throws SQLException
{
//to do
}
}

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