第三篇——JDBC数据库之添加数据

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本文介绍如何使用JDBC向数据库中添加数据，包括使用PreparedStatement设置参数及执行SQL语句的方法。涵盖从前端表单验证到后台数据库操作的全过程。

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通过JDBC向数据库中添加数据，可以使用INSERT语句实现插入数据SQL语句，对于SQL语句中的参数可以只用占位符“？”代替，然后通过PreparedStatement对其赋值以及执行SQL。

步骤说明：
1、代码请参考——第二篇JDBC操作数据库之查询数据。

2、在第二篇基础上继续实现功能——第三篇JDBC数据库之添加数据。

一、bookList.jsp

1.在基础上添加<a href="bookAdd.jsp">新增图书</a>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page import="com.entity.*" %>
<%
    String path = request.getContextPath();
    String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
    <base href="<%=basePath%>">

    <title>图书列表</title>

    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">

	<link rel="stylesheet" type="text/css" href="css/bookList.css">


</head>

<body>
    <form action="" method="post">
        <table width="80%" align="center">
            <div class="list">图书列表</div>
            <ul>
                <li><a href="bookAdd.jsp">新增图书</a> </li>
                <li>xxx</li>
                <li>xxx</li>
                <li>xxx</li>
            </ul>
            <tr>
                <td>图书编号</td>
                <td>图书名称</td>
                <td>图书价格</td>
                <td>图书数量</td>
                <td>图书作者</td>
                <td>图书修改</td>
                <td>图书删除</td>
            </tr>
            <c:forEach var="bookitem" items="${booklist}">
                <tr>
                    <td>${bookitem.id}</td>
                    <td>${bookitem.name}</td>
                    <td>${bookitem.price}</td>
                    <td>${bookitem.bookCount}</td>
                    <td>${bookitem.author}</td>
                    <td>dd</td>
                    <td>dd</td>
                </tr>
            </c:forEach>
        </table>
    </form>
</body>
</html>

二、bookAdd.jsp

1.增加检查功能(java script)实现

2.跳转servlet------<%=request.getContextPath()%>/BookAdd

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8" %>
<%
    String path = request.getContextPath();
    String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
    <base href="<%=basePath%>">

    <title>新增图书</title>

    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
    <script type="text/javascript">
        function check(form) {
            with(form){
                //with(form)相当于if(form.id.value == "")
                if(id.value == ""){
                    alert("图书编号不能为空");
                    return false;
                }
                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(bookCount.value == ""){
                    alert("图书数量不能为空");
                    return false;
                }
                if(author.value == ""){
                    alert("图书作者不能为空");
                    return false;
                }
                return true;
            }
        }
    </script>

</head>

<body>
    <form action="<%=request.getContextPath()%>/BookAdd" method="post" onsubmit="return check(this)">
        <div>
            <h1>新增图书信息</h1>
            <table>
                <tr>
                    <td>图书编号:</td>
                    <td><input type="text" name="id"></td>
                </tr>
                <tr>
                    <td>图书名称:</td>
                    <td><input type="text" name="name"></td>
                </tr>
                <tr>
                    <td>图书价格:</td>
                    <td><input type="text" name="price"></td>
                </tr>
                <tr>
                    <td>图书数量:</td>
                    <td><input type="text" name="bookCount"></td>
                </tr>
                <tr>
                    <td>图书作者:</td>
                    <td><input type="text" name="author"></td>
                </tr>
                <tr>
                    <td colspan="1"><input type="submit" value="新增"></td>
                    <td colspan="1"><input type="reset" value="重置"></td>
                </tr>
            </table>
        </div>
    </form>
</body>
</html>

三、BookAdd.java

1.根据input标签name属性获取值

2.调用模型---调用方法

3.response重定向

package com.control;

import com.model.BookModel;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Created by Ray on 2018/3/11 0011.
 **/
public class BookAdd extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //根据input name获取值
        int id = Integer.valueOf(request.getParameter("id"));
        String name = request.getParameter("name");
        double price = Double.valueOf(request.getParameter("price"));
        int bookCount = Integer.valueOf(request.getParameter("bookCount"));
        String author = request.getParameter("author");

        // 输出name 解决乱码
        System.out.println("name = " + name);

        //调用模型
        BookModel BookModel = new BookModel();
        //调用新增方法
        BookModel.addBook(id,name,price,bookCount,author);
        //response重定向改变路径
        response.sendRedirect(request.getContextPath() + "/BookList");
    }
}

四、BookModel.java

1.添加图书信息的sql语句

2.对占位符进行赋值

package com.model;

import com.dbutil.Dbconn;
import com.entity.Book;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by Ray on 2018/3/11 0011.
 **/
public class BookModel {

    Dbconn Dbconn = new Dbconn();
    Connection conn = null;
    PreparedStatement ps;
    ResultSet rs;

    /**
    * @Author: Ray
    * @Date: 2018/3/11 0011
    * @Description: 查询所有图书信息
    * @Return: booklist
    */
    public List<Book> bookList(){
        //创建booklist集合
        List booklist = new ArrayList();
        Book Book = null;
        try{
            //创建Connection连接
            conn = Dbconn.getConnection();
            //查询所有图书信息的sql语句
            String sql = "select * from booktable";
            //获取PreparedStatement
            ps = conn.prepareStatement(sql);
            //执行查询
            rs = ps.executeQuery();
            //判断光标向后移动,并判断是否有效
            while (rs.next()){
                //实例化Book对象
                Book = new Book();
                //对id属性赋值
                Book.setId(rs.getInt("id"));
                //对name属性赋值
                Book.setName(rs.getString("name"));
                //对price属性赋值
                Book.setPrice(rs.getDouble("price"));
                //对bookCount属性赋值
                Book.setBookCount(rs.getInt("bookCount"));
                //对author属性赋值
                Book.setAuthor(rs.getString("author"));
                //将book对象添加到集合中
                booklist.add(Book);
            }
            //关闭连接
            Dbconn.closeConnection(conn,ps,rs);
        }catch (Exception e){
            e.printStackTrace();
        }
        //返回booklist集合
        return booklist;
    }

    /**
    * @Author: Ray
    * @Date: 2018/3/11 0011
    * @Description: 新增图书信息
    * @Return:
    */
    public void addBook(int id,String name,double price,int bookCount,String author){
        try{
            //创建Connection连接
            conn = Dbconn.getConnection();
            //添加图书信息的sql语句
            String sql = "insert into booktable(id,name,price,bookCount,author) values(?,?,?,?,?)";
            //获取PrepareStatement
            ps = conn.prepareStatement(sql);
            //对占位符进行赋值
            ps.setInt(1,id);
            ps.setString(2,name);
            ps.setDouble(3,price);
            ps.setInt(4,bookCount);
            ps.setString(5,author);
            //执行更新,返回更新锁影响的行数
            int row = ps.executeUpdate();
            if(row > 0){
                System.out.println("添加数据成功");
            }
            ps.close();
            conn.close();
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

五、web.xml

这个很关键,不能出错,否则访问会出现404错误

<?xml version="1.0" encoding="UTF-8"?>
<web-app>
    <servlet>
        <servlet-name>BookList</servlet-name>
        <servlet-class>com.control.BookList</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>BookList</servlet-name>
        <url-pattern>/BookList</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>BookAdd</servlet-name>
        <servlet-class>com.control.BookAdd</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>BookAdd</servlet-name>
        <url-pattern>/BookAdd</url-pattern>
    </servlet-mapping>
</web-app>

六、页面效果