JDBC操做數據庫——CRUD綜合應用實例

時間  2020-08-26
標籤 jdbc 數據庫 crud 綜合 應用 實例 欄目 Java 简体版
原文   原文鏈接

經過一個綜合型的例子加深對JDBC操做數據庫的增、刪、改、查的運用。javascript

經典的圖書信息錄入實例css


設計數據庫html

CREATE TABLE `tb_books`
(
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
   
 `name` varchar(45) NOT NULL,
   
 `price` double NOT NULL,
   
 `bookCount` int(10) unsigned NOT NULL,
   
 `author` varchar(45) NOT NULL,
   
 PRIMARY KEY (`id`)
)


wKioL1Lc1R6gdL0NAAHwzIdUb9A861.jpg


寫一個Book類對圖書信息進行封裝java

package com.lixiyu;
public class Book {
private int id;
private String name;
private double price;
private int bookCount;
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;
}
}




添加（insert）圖書信息操做mysql


建立AddBook.jsp頁面，用於對添加圖書信息進行處理web

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
    <%@page import="java.sql.Connection"%>
<%@page import="java.sql.DriverManager"%>
<%@page import="java.sql.PreparedStatement"%>
<!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=GB18030">
<title>Insert title here</title>
</head>
<body>
<%request.setCharacterEncoding("UTF-8"); %>
<jsp:useBean id="book" class="com.lixiyu.Book"></jsp:useBean>
<jsp:setProperty property="*" name="book"/>
<%
try{
    Class.forName("com.mysql.jdbc.Driver");//加載數據庫驅動，註冊到驅動管理器
    String url="jdbc:mysql://localhost:3306/db_test";//數據庫鏈接字符串
    String username="root";//數據庫用戶名
    String password="lixiyu";//數據庫密碼
    Connection conn=DriverManager.getConnection(url,username,password);//建立Connection鏈接
    String sql="insert into tb_books(name,price,bookCount,author)values(?,?,?,?)";//添加圖書信息sql語句
                                                                                                                                                                                                                                                                                                                                                                                                                       
    PreparedStatement ps=conn.prepareStatement(sql);//獲取PreparedStatement
    ps.setString(1,book.getName());//對SQL語句中的第1個參數賦值
    ps.setDouble(2,book.getPrice());
    ps.setInt(3,book.getbookCount());
    ps.setString(4,book.getAuthor());//對SQL語句中的第4個參數賦值
    int row=ps.executeUpdate();//執行更新操做，返回所影響的行數
    if(row>0){
        out.print("成功添加了"+row+"條數據");
    }
    ps.close();
    conn.close();
}catch(Exception e){
    out.print("圖書信息添加失敗！");
    e.printStackTrace();
}
%>
</body>
<a href="insert.jsp">返回</a>
</html>


建立insert.jsp，用於建立添加圖書信息所需的表單sql

<%@ 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>添加圖書信息</title>
<script type="text/javascript">
    function check(form){
        with(form){
            if(name.value == ""){
                alert("圖書名稱不能爲空");
                return false;
            }
            if(price.value == ""){
                alert("價格不能爲空");
                return false;
            }
            if(author.value == ""){
                alert("做者不能爲空");
                return false;
            }
            return true;
        }
    }
</script>
</head>
<body>
    <form action="AddBook.jsp" method="post" onsubmit="return check(this);">
        <table align="center" width="450">
            <tr>
                <td align="center" colspan="2">
                    <h2>添加圖書信息</h2>
                    <hr>
                </td>
            </tr>
            <tr>
                <td align="right">圖書名稱：</td>
                <td><input type="text" name="name" /></td>
            </tr>
            <tr>
                <td align="right">價　　格：</td>
                <td><input type="text" name="price" /></td>
            </tr>
            <tr>
                <td align="right">數　　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>
</body>
</html>

最後運行數據庫

wKioL1Lc2WaiySd8AABt3y2sBH4326.jpg

成功：app

wKiom1Lc2Yui_pabAABF1HO1eQA506.jpg


查詢（select）圖書信息操做jsp


建立FindServlet的servlet對象用於查詢全部圖書的信息。編寫doGet()方法，創建數據庫鏈接，並將全部查詢數據集合放置HttpServletRequest對象中，將請求轉發到jsp頁面中：

package com.lixiyu;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * Servlet implementation class FindServlet
 */
public class FindServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
                                                                                                                                                                                                                                                                                                                  
    /**
     * @see HttpServlet#HttpServlet()
     */
    public FindServlet() {
        super();
        // TODO Auto-generated constructor stub
    }
    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        try{
            Class.forName("com.mysql.jdbc.Driver");
            String url="jdbc:mysql://localhost:3306/db_test";
            String username="root";
            String password="lixiyu";
            Connection conn=DriverManager.getConnection(url,username,password);
            Statement stmt=conn.createStatement();//獲取statement對象
            String sql="select * from tb_books";
            ResultSet rs=stmt.executeQuery(sql);
            List<Book> list=new ArrayList<Book>();//實例化list對象
            while(rs.next()){
                Book book=new Book();
                book.setId(rs.getInt("id"));//對id屬性賦值
                book.setName(rs.getString("name"));
                book.setPrice(rs.getDouble("price"));
                book.setbookCount(rs.getInt("bookCount"));
                book.setAuthor(rs.getString("author"));
            list.add(book);//將圖書對象添加到集合中
            }
            request.setAttribute("list", list);//將圖書集合放置到request中
            rs.close();//關閉ResultSet
            stmt.close();//關閉Statement
            conn.close();//關閉Connection
        }catch(ClassNotFoundException e){
            e.printStackTrace();
        }catch(SQLException e){
            e.printStackTrace();
        }
        request.getRequestDispatcher("book_list.jsp").forward(request, response);//請求轉發到book_List.jsp
    }
    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }
}


在web.xml中添加映射：

<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>com.lixiyu.FindServlet</servlet-class>
 </servlet>
 <servlet-mapping>
   <servlet-name>FindServlet</servlet-name>
   <url-pattern>/FindServlet</url-pattern>
 </servlet-mapping>


建立book_list.jsp頁面，用於顯示查詢到的全部圖書信息

<%@ 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="com.lixiyu.Book"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>全部圖書信息</title>
<style type="text/css">
    td{font-size: 12px;}
    h2{margin: 0px}
                                                                                                                                                                                                                                                                                                 
</style>
</head>
<body>
    <table align="center" width="450" border="1" height="180" bordercolor="white" bgcolor="" cellpadding="1" cellspacing="1">
        <tr bgcolor="white">
            <td align="center" colspan="5">
                <h2>全部圖書信息</h2>
            </td>
        </tr>
        <tr align="center" bgcolor="#e1ffc1" >
            <!--  <td><b>ID</b></td>-->
            <td><b>圖書名稱</b></td>
            <td><b>價格</b></td>
            <td><b>數量</b></td>
            <td><b>做者</b></td>
        </tr>
            <%
                // 獲取圖書信息集合
                    List<Book>list = (List<Book>)request.getAttribute("list");
                    // 判斷集合是否有效
                    if(list == null || list.size() < 1){
                        out.print("沒有數據！");
                    }else{
                        // 遍歷圖書集合中的數據
                        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 action="UpdateServlet" method="post" onsubmit="return check(this);">
                <input type="hidden" name="id" value="<%=book.getId()%>">
                <input type="text" name="bookCount" size="3">
                                                                                                                                                                                                                                                                                                             
                </form>
                                                                                                                                                                                                                                                                                                             
                </tr>
                                                                                                                                                                                                                                                                                                             
            <%
                    }
                }
            %>
    </table>
    <br>
</body>
</html>


建立index.jsp主頁，用於請求查看全部圖書信息：

<body>
<a href="FindServlet">查看全部圖書</a>
</body>

運行該實例

wKioL1Lc3QTylxv_AABOjiFfdvU910.jpg

wKiom1Lc3SiR9yGMAACeYDmI6lY322.jpg


修改（update）圖書信息操做


在book_list.jsp中添多一列修改：

<td>
                <form 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">
                </form></td>


建立UpdateServlet.jsp編寫doPost方法對圖書信息請求進行處理：

package com.lixiyu;
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;
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int id = Integer.valueOf(request.getParameter("id"));
        int bookCount = Integer.valueOf(request.getParameter("bookCount"));
        try {
            // 加載數據庫驅動，註冊到驅動管理器
            Class.forName("com.mysql.jdbc.Driver");
            // 數據庫鏈接字符串
            String url = "jdbc:mysql://localhost:3306/db_test";
            // 數據庫用戶名
            String username = "root";
            // 數據庫密碼
            String password = "lixiyu";
            // 建立Connection鏈接
            Connection conn = DriverManager.getConnection(url,username,password);
            // 更新SQL語句
            String sql = "update tb_books set bookcount=? where id=?";
            // 獲取PreparedStatement
            PreparedStatement ps = conn.prepareStatement(sql);
            // 對SQL語句中的第一個參數賦值
            ps.setInt(1, bookCount);
            // 對SQL語句中的第二個參數賦值
            ps.setInt(2, id);
            // 執行更新操做
            ps.executeUpdate();
            // 關閉PreparedStatement
            ps.close();
            // 關閉Connection
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 重定向到FindServlet
        response.sendRedirect("FindServlet");
    }
}

添加xml映射

<servlet>
    <display-name>UpdateServlet</display-name>
    <servlet-name>UpdateServlet</servlet-name>
    <servlet-class>com.lixiyu.UpdateServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>UpdateServlet</servlet-name>
    <url-pattern>/UpdateServlet</url-pattern>
  </servlet-mapping>


運行後

wKiom1Lc4FfSbOO9AAD9RNsUFKY761.jpg

wKiom1Lc4GbCah6KAAEDugnF2Y4344.jpg


刪除（delete）圖書信息操做


編寫刪除操做的servlet，命名爲DeleteServlet:

package com.lixiyu;
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 DeleteServlet
 */
public class DeleteServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
                                                                                                                                         
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 獲取圖書id
        int id = Integer.valueOf(request.getParameter("id"));
        try {
            // 加載數據庫驅動，註冊到驅動管理器
            Class.forName("com.mysql.jdbc.Driver");
            // 數據庫鏈接字符串
            String url = "jdbc:mysql://localhost:3306/db_test";
            // 數據庫用戶名
            String username = "root";
            // 數據庫密碼
            String password = "lixiyu";
            // 建立Connection鏈接
            Connection conn = DriverManager.getConnection(url,username,password);
            // 刪除圖書信息的SQL語句
            String sql = "delete from tb_books where id=?";
            // 獲取PreparedStatement
            PreparedStatement ps = conn.prepareStatement(sql);
            // 對SQL語句中的第一個佔位符賦值
            ps.setInt(1, id);
            // 執行更新操做
            ps.executeUpdate();
            // 關閉PreparedStatement
            ps.close();
            // 關閉Connection
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 重定向到FindServlet
        response.sendRedirect("FindServlet");
    }
}

添加xml映射：

<servlet>
    <description></description>
    <display-name>DeleteServlet</display-name>
    <servlet-name>DeleteServlet</servlet-name>
    <servlet-class>com.lixiyu.DeleteServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>DeleteServlet</servlet-name>
    <url-pattern>/DeleteServlet</url-pattern>
  </servlet-mapping>
</web-app>


整合CRUD操做


在前面book_list.jsp頁面中進行整合：

<%@ 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="com.lixiyu.Book"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>全部圖書信息</title>
<style type="text/css">
td{font-size: 12px;}
h2{margin: 0px}
</style>
</head>
<body>
<table align="center" width="450" border="1" height="180" bordercolor="white" bgcolor="" cellpadding="1" cellspacing="1">
<tr bgcolor="white">
<td align="center" colspan="5">
<h2>全部圖書信息</h2>
</td>
</tr>
<tr align="center" bgcolor="#e1ffc1" >
<!--  <td><b>ID</b></td>-->
<td><b>圖書名稱</b></td>
<td><b>價格</b></td>
<td><b>數量</b></td>
<td><b>做者</b></td>
<td><b>修改數量</b></td>
<td><b>刪 除</b></td>
</tr>
<%
// 獲取圖書信息集合
List<Book>list = (List<Book>)request.getAttribute("list");
// 判斷集合是否有效
if(list == null || list.size() < 1){
out.print("沒有數據！");
}else{
// 遍歷圖書集合中的數據
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 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">
</form>
</td>
<td><a href="DeleteServlet?id=<%=book.getId() %>">刪除</a>
</td>
</tr>
<%
}
}
%>
</table>
<br>
<center>
<form   action="insert.jsp" method="post" onsubmit="return check(this);">
 <input type="submit" name="" value="添加數據" >
</form></center>
</body>
</html>


將前面AddBook.jsp中的頁面連接進行修改

<a href="FindServlet">返回</a>


所以整個操做都回歸到book_list.jsp來顯示了

運行

wKioL1Lc4ziS8nEnAABdTGVs-EI747.jpg

CRUD操做整合到一個頁面顯示：

wKiom1Lc416S0m57AAFWtV79j3M565.jpg



此次JDBC先寫到這，下次有時間再總結一下批處理、調用存儲過程、分頁查詢的相關操做。

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