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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=truecharacterEncoding=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); 
 
      ListBook> list = new ArrayListBook>(); 
      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=truecharacterEncoding=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 
      ListBook> list = (ListBook>) 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=truecharacterEncoding=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

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。

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