有声,大主宰,大主宰之灵路天蚕土豆

一、JSP和Servlet的簡(jiǎn)單介紹

1、Servlet和JSP簡(jiǎn)介：

Java開(kāi)發(fā)Web應(yīng)用程序時(shí)用到的技術(shù)主要有兩種，即Servlet和JSP，Servlet是在服務(wù)器端執(zhí)行的Java程序，一個(gè)被稱(chēng)為Servlet容器的程序（其實(shí)就是服務(wù)器）負(fù)責(zé)執(zhí)行Java程序，而JSP(Java Server Page)則是一個(gè)頁(yè)面，由JSP容器負(fù)責(zé)執(zhí)行.

2、Servlet和JSP的區(qū)別：

Servlet以Java程序?yàn)橹鳎?輸出HTML代碼時(shí)需要使用out.println函數(shù)，也就是說(shuō)Java中內(nèi)嵌HTML；而JSP則以HTML頁(yè)面為主，需要寫(xiě)Java代碼時(shí)則在頁(yè)面中直接插入Java代碼，即HTML中內(nèi)嵌Java.

3、MVC模型

MVC模型就是將數(shù)據(jù)、邏輯處理、用戶(hù)界面分離的一種方法

1）、M(Model, 模型)：用于數(shù)據(jù)處理、邏輯處理

2）、V(View，視圖)：用于顯示用戶(hù)界面

3）、C(Controller，控制器)：根據(jù)客戶(hù)端的請(qǐng)求控制邏輯走向和畫(huà)面

而在Java中，MVC這三個(gè)部分則分別對(duì)應(yīng)于 JavaBeans、JSP和Servlet

1）、M = JavaBeans：用于傳遞數(shù)據(jù)，擁有與數(shù)據(jù)相關(guān)的邏輯處理

2）、V = JSP：從Model接收數(shù)據(jù)并生成HTML

3）、C = Servlet：接收HTTP請(qǐng)求并控制Model和View

4、jdbc連接，可參考文章：點(diǎn)擊打開(kāi)鏈接

二、代碼演示，實(shí)現(xiàn)了book的添加刪除和修改功能

1、環(huán)境的配置

myeclipse+tomcat+MySQL

2、Book中bean類(lèi)

package example.bean.book;  
public class Book { 
  // 編號(hào) 
  private int id; 
  // 圖書(shū)名稱(chēng) 
  private String name; 
  // 價(jià)格 
  private double price; 
  // 數(shù)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類(lèi)

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 { 
      // 加載數(shù)據(jù)庫(kù)驅(qū)動(dòng)，注冊(cè)到驅(qū)動(dòng)管理器 
      Class.forName("com.mysql.jdbc.Driver"); 
      // 數(shù)據(jù)庫(kù)連接字符串 
      String url = "jdbc:mysql://localhost:3306/db_book?useUnicode=truecharacterEncoding=utf-8"; 
      // 數(shù)據(jù)庫(kù)用戶(hù)名 
      String username = "root"; 
      // 數(shù)據(jù)庫(kù)密碼 
      String password = ""; 
      // 創(chuàng)建Connection連接 
      Connection conn = DriverManager.getConnection(url, username, 
          password); 
      // 添加圖書(shū)信息的SQL語(yǔ)句 
      String sql = "select * from tb_books"; 
      // 獲取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類(lèi)

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 { 
      // 加載數(shù)據(jù)庫(kù)驅(qū)動(dòng)，注冊(cè)到驅(qū)動(dòng)管理器 
      Class.forName("com.mysql.jdbc.Driver"); 
      // 數(shù)據(jù)庫(kù)連接字符串 
      String url = "jdbc:mysql://localhost:3306/db_book"; 
      // 數(shù)據(jù)庫(kù)用戶(hù)名 
      String username = "root"; 
      // 數(shù)據(jù)庫(kù)密碼 
      String password = ""; 
      // 創(chuàng)建Connection連接 
      Connection conn = DriverManager.getConnection(url, username, 
          password); 
      // 更新SQL語(yǔ)句 
      String sql = "update tb_books set bookcount=? where id=?"; 
      // 獲取PreparedStatement 
      PreparedStatement ps = conn.prepareStatement(sql); 
      // 對(duì)SQL語(yǔ)句中的第一個(gè)參數(shù)賦值 
      ps.setInt(1, bookCount); 
      // 對(duì)SQL語(yǔ)句中的第二個(gè)參數(shù)賦值 
      ps.setInt(2, id); 
      // 執(zhí)行更新操作 
      ps.executeUpdate(); 
      // 關(guān)閉PreparedStatement 
      ps.close(); 
      // 關(guān)閉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類(lèi)

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 { 
//     // 加載數(shù)據(jù)庫(kù)驅(qū)動(dòng)，注冊(cè)到驅(qū)動(dòng)管理器 
//     Class.forName("com.mysql.jdbc.Driver"); 
//     // 數(shù)據(jù)庫(kù)連接字符串 
//     String url = "jdbc:mysql://localhost:3306/db_book"; 
//     // 數(shù)據(jù)庫(kù)用戶(hù)名 
//     String username = "root"; 
//     // 數(shù)據(jù)庫(kù)密碼 
//     String password = ""; 
//     // 創(chuàng)建Connection連接 
//     Connection conn = DriverManager.getConnection(url, username, 
//         password); 
//     // 刪除圖書(shū)信息的SQL語(yǔ)句 
//     String sql = "delete from tb_books where id=?"; 
//     // 獲取PreparedStatement 
//     PreparedStatement ps = conn.prepareStatement(sql); 
//     // 對(duì)SQL語(yǔ)句中的第一個(gè)占位符賦值 
//     ps.setInt(1, id); 
//     // 執(zhí)行更新操作 
//     ps.executeUpdate(); 
//     // 關(guān)閉PreparedStatement 
//     ps.close(); 
//     // 關(guān)閉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訪問(wèn)url映射配置：

由于客戶(hù)端是通過(guò)URL地址訪問(wèn)web服務(wù)器中的資源，所以Servlet程序若想被外界訪問(wèn)，必須把servlet程序映射到一個(gè)URL地址上，這個(gè)工作在web.xml文件中使用servlet>元素和servlet-mapping>元素完成，servlet>元素用于注冊(cè)Servlet，它包含有兩個(gè)主要的子元素：servlet-name>和servlet-class>，分別用于設(shè)置Servlet的注冊(cè)名稱(chēng)和Servlet的完整類(lèi)名。

一個(gè)servlet-mapping>元素用于映射一個(gè)已注冊(cè)的Servlet的一個(gè)對(duì)外訪問(wèn)路徑，它包含有兩個(gè)子元素：servlet-name>和url-pattern>，分別用于指定Servlet的注冊(cè)名稱(chēng)和Servlet的對(duì)外訪問(wèn)路徑.另外：同一個(gè)Servlet可以被映射到多個(gè)URL上，即多個(gè)servlet-mapping>元素的servlet-name>子元素的設(shè)置值可以是同一個(gè)Servlet的注冊(cè)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頁(yè)面

1）、index.jsp web頁(yè)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>添加圖書(shū)信息/title> 
 
script type="text/javascript"> 
  function check(form) { 
    with (form) { 
      if (name.value == "") { 
        alert("圖書(shū)名稱(chēng)不能為空"); 
        return false; 
      } 
 
      if (price.value == "") { 
        alert("圖書(shū)價(jià)格不能為空"); 
        return false; 
      } 
 
      if (author.value == "") { 
        alert("作者不能為空"); 
        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>添加圖書(shū)信息/h2> 
        hr> 
      /td> 
    /tr> 
 
    tr> 
      td align="right">圖書(shū)名稱(chēng)：/td> 
      td>input type="text" name="name">/td> 
    /tr> 
 
    tr> 
      td align="right">價(jià) 格：/td> 
      td>input type="text" name="price">/td> 
    /tr> 
 
    tr> 
      td align="right">數(shù) 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">查詢(xún)圖書(shū)信息/a> 
/h2> 
 
/body> 
/html>

2)、addbook.jsp 添加書(shū)籍成功或者失敗后的顯示頁(yè)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>添加結(jié)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 { 
      // 加載數(shù)據(jù)庫(kù)驅(qū)動(dòng)，注冊(cè)到驅(qū)動(dòng)管理器 
      Class.forName("com.mysql.jdbc.Driver"); 
      // 數(shù)據(jù)庫(kù)連接字符串 
      String url = "jdbc:mysql://localhost:3306/db_book?useUnicode=truecharacterEncoding=utf-8"; 
      // 數(shù)據(jù)庫(kù)用戶(hù)名 
      String username = "root"; 
      // 數(shù)據(jù)庫(kù)密碼 
      String password = ""; 
      // 創(chuàng)建Connection連接 
      Connection conn = DriverManager.getConnection(url, username, 
          password); 
      // 添加圖書(shū)信息的SQL語(yǔ)句 
      String sql = "insert into tb_books(name,price,bookCount,author) values(?,?,?,?)"; 
      // 獲取PreparedStatement 
      PreparedStatement ps = conn.prepareStatement(sql); 
      // 對(duì)SQL語(yǔ)句中的第1個(gè)參數(shù)賦值 
      ps.setString(1, book.getName()); 
      // 對(duì)SQL語(yǔ)句中的第2個(gè)參數(shù)賦值 
      ps.setDouble(2, book.getPrice()); 
      // 對(duì)SQL語(yǔ)句中的第3個(gè)參數(shù)賦值 
      ps.setInt(3, book.getBookCount()); 
      // 對(duì)SQL語(yǔ)句中的第4個(gè)參數(shù)賦值 
      ps.setString(4, book.getAuthor()); 
      // 執(zhí)行更新操作，返回所影響的行數(shù) 
      int row = ps.executeUpdate(); 
      // 判斷是否更新成功 
      if (row > 0) { 
        // 更新成輸出信息 
        out.print("成功添加了 " + row + "條數(shù)據(jù)！"); 
      } 
      // 關(guān)閉PreparedStatement，釋放資源 
      ps.close(); 
      // 關(guān)閉Connection，釋放資源 
      conn.close(); 
    } catch (Exception e) { 
      out.print("圖書(shū)信息添加失??！"); 
      e.printStackTrace(); 
    } 
  %> 
  br> 
  a href="index.jsp">返回/a> 
/body> 
/html>

3)、book_list.jsp 查找所有書(shū)籍信息的顯示頁(yè)面，以表格方式顯示

!--%@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>所有圖書(shū)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("請(qǐng)輸入更新數(shù)量！"); 
        return false; 
      } 
      if (isNaN(bookCount.value)) { 
        alert("格式錯(cuò)誤！"); 
        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>所有圖書(shū)信息/h2> 
      /td> 
    /tr> 
    tr align="center" bgcolor="#e1ffc1"> 
      td>b>ID/b>/td> 
      td>b>圖書(shū)名稱(chēng)/b>/td> 
      td>b>價(jià)格/b>/td> 
      td>b>數(shù)量/b>/td> 
      td>b>作者/b>/td> 
      td>b>修改/b>/td> 
      td>b>刪除/b>/td> 
    /tr> 
    % 
      // 獲取圖書(shū)信息集合 
      ListBook> list = (ListBook>) request.getAttribute("list"); 
      // 判斷集合是否有效 
      if (list == null || list.size()  1) { 
        out.print("沒(méi)有數(shù)據(jù)！"); 
      } else { 
        // 遍歷圖書(shū)集合中的數(shù)據(jù) 
        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="修改數(shù)量"> 
        /form> 
      /td> 
      td> 
      a href="DeleteServlet?id=%=book.getId()%>">刪除/a> 
      /td> 
 
 
    /tr> 
    % 
      } 
      } 
    %> 
  /table> 
  h2 align="center"> 
    a href="index.jsp">返回添加圖書(shū)信息頁(yè)面/a> 
  /h2> 
 
/body> 
/html>

6、jdbc簡(jiǎn)單的封裝

1）、ConnectionFactory.java工廠類(lèi)

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數(shù)據(jù)庫(kù)操作封裝類(lèi)

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); 
      // 對(duì)SQL語(yǔ)句中的第一個(gè)占位符賦值 
      ptmt.setInt(1, id); 
      // 執(zhí)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 
     
  } 
   
 
}

源代碼下載鏈接

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