jsp+servlet+jdbc实现对数据库的增删改查

时间 2019-11-19

标签 jsp+servlet+jdbc jsp servlet jdbc 实现数据库增删栏目 JSP 繁體版

原文原文链接

1、JSP和Servlet的简单介绍：javascript

一、Servlet和JSP简介：
css

　　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。html

二、Servlet和JSP的区别：
java

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

三、MVC模型web

MVC模型就是将数据、逻辑处理、用户界面分离的一种方法。sql

1）、M(Model，模型)：用于数据处理、逻辑处理数据库

2）、V(View，视图)：用于显示用户界面tomcat

3）、C(Controller，控制器)：根据客户端的请求控制逻辑走向和画面服务器

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

2、代码演示，实现了book的添加删除和修改功能

一、环境的配置

myeclipse+tomcat+MySQL

二、Book中bean类：提供字段属性，并提供get/set方法

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; // 做者 
  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; } }

三、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;//导入包下的Book类 /** * 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"); // 数据库链接字符串 
      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 = ""; // 建立Connection链接 
      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"); // 数据库链接字符串 
      String url = "jdbc:mysql://localhost:3306/db_book"; // 数据库用户名 
      String username = "root"; // 数据库密码 
      String password = ""; // 建立Connection链接 
      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); // 执行更新操做 
 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"); //     // 数据库链接字符串 // String url = "jdbc:mysql://localhost:3306/db_book"; //     // 数据库用户名 // String username = "root"; //     // 数据库密码 // String password = ""; //     // 建立Connection链接 // 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); //     // 执行更新操做 // 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); } }

四、servlet访问url映射配置：

　　因为客户端是经过URL地址访问web服务器中的资源，因此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，这个工做在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能够被映射到多个URL上，即多个<servlet-mapping>元素的<servlet-name>子元素的设置值能够是同一个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>

五、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("做者不能为空"); 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">做 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"); // 数据库链接字符串 
      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 = ""; // 建立Connection链接 
      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()); // 执行更新操做，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 查找全部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>全部图书信息</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>全部图书信息</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>做者</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>

六、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数据库操做封装类

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); // 执行更新操做 
 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 
 } }