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;
  } 

}

3、Servlet类

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<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

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<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

<?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

<%@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

<%@ 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

<!--<%@page import="sun.awt.SunHints.Value"%>-->
<%@ 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

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 

  } 

}

源代码下载链接

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