jsp+servlet+jdbc实现对数据库的增删改查
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
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;
}
}
1)、FindServlet.java
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 list = new ArrayList();
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
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
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
eg:上例中的web.xml
JdbcConnection
index.html
index.htm
index.jsp
default.html
default.htm
default.jsp
FindServlet
FindServlet
example.servlet.book.FindServlet
FindServlet
/FindServlet
UpdateServlet
UpdateServlet
example.servlet.book.UpdateServlet
UpdateServlet
/UpdateServlet
DeleteServlet
DeleteServlet
example.servlet.book.DeleteServlet
DeleteServlet
/DeleteServlet
5、jsp页面
1）、index.jsp web页面主界面
<%@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"%>
添加图书信息
查询图书信息
2)、addbook.jsp 添加书籍成功或者失败后的显示页面
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@page import="java.sql.Connection"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.PreparedStatement"%>
添加结果
<%
request.setCharacterEncoding("utf-8");
%>
返回
3)、book_list.jsp 查找所有书籍信息的显示页面，以表格方式显示
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@page import="java.util.List"%>
<%@page import="example.bean.book.Book"%>
所有图书信息
所有图书信息
ID
图书名称
价格
数量
作者
修改
删除
<%
// 获取图书信息集合
List list = (List) 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) {
%>
<%=book.getId()%>
<%=book.getName()%>
<%=book.getPrice()%>
<%=book.getBookCount()%>
<%=book.getAuthor()%>
删除
<%
}
}
%>
返回添加图书信息页面
6、jdbc简单的封装
1）、ConnectionFactory.java工厂类
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
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
}
}