JEE_JDBC1
JDBC是Java程序与数据库系统通信的标准API,定义在JDK的API中,通过JDBC技术,Java程序可以很方便地与各种数据库进行交互,JDBC在Java程序与数据库系统之间建立了一座桥梁。
JDBC API:
Connection接口.
DriverManager类.
Statement接口.
PreparedStatement接口.
ResultSet接口.
JDBC连接数据库的过程:
1.注册数据库驱动:
2.构建数据库连接URL:
3.获取Connection对象
(JSP连接MySQL:先启动MySQL,创建Web项目及导包)
例:通过JDBC连接MySQL数据库:
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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.SQLException"%> <%@page import="java.sql.DriverManager"%> <%@page import="java.util.Enumeration"%><html> <head> <meta http-equiv="Content-Type" content="text/html; charset=GB18030"> <title>连接MySQL数据库</title> </head> <body> <% 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/mysql"; // 数据库用户名 String username = "root"; // 数据库密码 String password = "111"; // 创建Connection连接 Connection conn = DriverManager.getConnection(url,username,password); // 判断 数据库连接是否为空 if(conn != null){ // 输出连接信息 out.println("数据库连接成功!"); // 关闭数据库连接 conn.close(); }else{ // 输出连接信息 out.println("数据库连接失败!"); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } %> </body> </html>
<?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>11.1</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> </web-app>
JDBC操作MySQL数据库:
1.添加数据:
//JavaBean package com.lyq.bean; /** * 图书实体类 * @author Li YongQiang */ 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; } }
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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>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("价格不能为空"); return false; } if(author.value == ""){ alert("作者不能为空"); 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> </body> </html>
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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=GB18030"> <title>添加结果</title> </head> <body> <%request.setCharacterEncoding("GB18030"); %> <jsp:useBean id="book" class="com.lyq.bean.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_database11"; // 数据库用户名 String username = "root"; // 数据库密码 String password = "111"; // 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_book(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>
<?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>11.2</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> </web-app>
2.查询数据: ResultSet集合所查询的数据是位于集合的中间位置,在第一条数据之前与最后一条数据之后都还有一个位置,
默认情况下ResultSet的光标位置在第一行数据之前,所以在第一次获取数据时就需要移动光标的位置。
由于这个位置关系,使用Java之中的for循环,do...while循环等都不能对其很好地进行遍历,此处可以用 "while(rs.next())" 来遍历.
通过光标定位到查询结果中的指定行后,通过ResultSet对象提供的一系列getXxx()方法就可获取当前行的数据.
index.jsp---FindServlet.java---book_list.jsp.(JavaBean,web.xml)
package com.lyq.bean; /** * 图书实体类 * @author Li YongQiang */ 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; } }
package com.lyq.bean; 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.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 查询图书信息的Servlet对象 * @author Li YongQiang * */ public class FindServlet extends HttpServlet { private static final long serialVersionUID = 1L; 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_database11"; // 数据库用户名 String username = "root"; // 数据库密码 String password = "111"; // 创建Connection连接 Connection conn = DriverManager.getConnection(url,username,password); // 获取Statement Statement stmt = conn.createStatement(); // 添加图书信息的SQL语句 String sql = "select * from tb_book"; // 执行查询 ResultSet rs = stmt.executeQuery(sql); // 实例化List对象 List<Book> list = new ArrayList<Book>(); // 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 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")); // 将图书对象添加到集合中 list.add(book); } // 将图书集合放置到request之中 request.setAttribute("list", list); rs.close(); // 关闭ResultSet stmt.close(); // 关闭Statement conn.close(); // 关闭Connection } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } // 请求转发到book_list.jsp request.getRequestDispatcher("book_list.jsp").forward(request, response); } }
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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.lyq.bean.Book"%> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=GB18030"> <title>所有图书信息</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="black" cellpadding="1" cellspacing="1"> <tr bgcolor="white"> <td align="center" colspan="5"> <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> </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> </tr> <% } } %> </table> </body> </html>
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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>查看所有图书</title> </head> <body> <a href="FindServlet">查看所有图书</a> </body> </html>
<?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>11.3</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>com.lyq.bean.FindServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>FindServlet</servlet-name> <url-pattern>/FindServlet</url-pattern> </servlet-mapping> </web-app>
3.修改数据
由于SQL语句中要传递参数,修改数据应该使用PreparedStatement对象进行操作.
index.jsp---FindServlet.java---book_list.jsp---UpdateServlet.java---FindServlet.java---book_list.jsp.(JavaBean,web.xml)
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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>查看所有图书</title> </head> <body> <a href="FindServlet">查看所有图书</a> </body> </html>
package com.lyq.bean; 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.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 查询图书信息的Servlet对象 * @author Li YongQiang * */ public class FindServlet extends HttpServlet { private static final long serialVersionUID = 1L; 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_database11"; // 数据库用户名 String username = "root"; // 数据库密码 String password = "111"; // 创建Connection连接 Connection conn = DriverManager.getConnection(url,username,password); // 获取Statement Statement stmt = conn.createStatement(); // 添加图书信息的SQL语句 String sql = "select * from tb_book"; // 执行查询 ResultSet rs = stmt.executeQuery(sql); // 实例化List对象 List<Book> list = new ArrayList<Book>(); // 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 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")); // 将图书对象添加到集合中 list.add(book); } // 将图书集合放置到request之中 request.setAttribute("list", list); rs.close(); // 关闭ResultSet stmt.close(); // 关闭Statement conn.close(); // 关闭Connection } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } // 请求转发到book_list.jsp request.getRequestDispatcher("book_list.jsp").forward(request, response); } }
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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.lyq.bean.Book"%> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=GB18030"> <title>所有图书信息</title> <style type="text/css"> form{margin: 0px;} td{font-size: 12px;} h2{margin: 2px} </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="500" border="1" height="170" bordercolor="white" bgcolor="black" cellpadding="1" cellspacing="1"> <tr bgcolor="white"> <td align="center" colspan="6"> <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>修改数量</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 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> </tr> <% } } %> </table> </body> </html>
package com.lyq.bean; 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_database11"; // 数据库用户名 String username = "root"; // 数据库密码 String password = "111"; // 创建Connection连接 Connection conn = DriverManager.getConnection(url,username,password); // 更新SQL语句 String sql = "update tb_book 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"); } }
package com.lyq.bean; /** * 图书实体类 * @author Li YongQiang */ 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; } }
<?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>11.4</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> <display-name>UpdateServlet</display-name> <servlet-name>UpdateServlet</servlet-name> <servlet-class>com.lyq.bean.UpdateServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>UpdateServlet</servlet-name> <url-pattern>/UpdateServlet</url-pattern> </servlet-mapping> <servlet> <display-name>FindServlet</display-name> <servlet-name>FindServlet</servlet-name> <servlet-class>com.lyq.bean.FindServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>FindServlet</servlet-name> <url-pattern>/FindServlet</url-pattern> </servlet-mapping> </web-app>
4.删除数据
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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.lyq.bean.Book"%> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=GB18030"> <title>所有图书信息</title> <style type="text/css"> form{margin: 0px;} td{font-size: 12px;} h2{margin: 2px} </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="170" bordercolor="white" bgcolor="black" cellpadding="1" cellspacing="1"> <tr bgcolor="white"> <td align="center" colspan="6"> <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>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> <a href="DeleteServlet?id=<%=book.getId()%>">删除</a> </td> </tr> <% } } %> </table> </body> </html>
package com.lyq.bean; 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 { // 获取图书id 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_database11"; // 数据库用户名 String username = "root"; // 数据库密码 String password = "111"; // 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_book 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(); } catch (Exception e) { e.printStackTrace(); } // 重定向到FindServlet response.sendRedirect("FindServlet"); } }
5.批处理
PreparedStatement对象的批处理操作,单条数据提交用.addBatch(),批处理提交是用.executeBatch(),而不是executeUpdate(),executeQuery().
另外,JavaBean对象的使用包括<jsp:useBean>实例化对象,或者直接创建用其public class创建类对象.
JavaBean对象的操作包括<jsp:setProperty>,<jsp:getProperty>,还可以直接调用其中定义的方法函数(saveBatch).
package com.lyq; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.SQLException; import java.util.Random; /** * 批处理 * @author Li YongQiang */ public class Batch { /** * 获取数据库连接 * @return Connection对象 */ public Connection getConnection(){ // 数据库连接 Connection conn = null; 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_database11"; // 数据库用户名 String username = "root"; // 数据库密码 String password = "111"; // 创建Connection连接 conn = DriverManager.getConnection(url,username,password); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } // 返回数据库连接 return conn; } /** * 批量添加数据 * @return 所影响的行数 */ public int saveBatch(){ // 行数 int row = 0 ; // 获取数据库连接 Connection conn = getConnection(); try { // 插入数据的SQL语句 String sql = "insert into tb_student_batch(id,name,sex,age) values(?,?,?,?)"; // 创建PreparedStatement PreparedStatement ps = conn.prepareStatement(sql); // 实例化Random Random random = new Random(); // 循环添加数据 for (int i = 0; i < 10; i++) { // 对SQL语句中的第1个参数赋值 ps.setInt(1, i+1); // 对SQL语句中的第2个参数赋值 ps.setString(2, "学生" + i); // 对SQL语句中的第3个参数赋值 ps.setBoolean(3, i % 2 == 0 ? true : false); // 对SQL语句中的第4个参数赋值 ps.setInt(4, random.nextInt(5) + 10); // 添加批处理命令 ps.addBatch(); } // 执行批处理操作并返回计数组成的数组 int[] rows = ps.executeBatch(); // 对行数赋值 row = rows.length; // 关闭PreparedStatement ps.close(); // 关闭Connection conn.close(); } catch (Exception e) { e.printStackTrace(); } // 返回添加的行数 return row; } }
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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>首页</title> </head> <body> <jsp:useBean id="batch" class="com.lyq.Batch"></jsp:useBean> <% // 执行批量插入操作 int row = batch.saveBatch(); out.print("批量插入了【" + row + "】条数据!"); %> </body> </html>
<?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>11.6</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> </web-app>
6.存储过程
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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.lyq.bean.Book"%> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=GB18030"> <title>所有图书信息</title> <style type="text/css"> td{font-size: 12px;} h2{margin: 0px} </style> </head> <body> <jsp:useBean id="findBook" class="com.lyq.bean.FindBook"></jsp:useBean> <table align="center" width="450" border="1" height="180" bordercolor="white" bgcolor="black" cellpadding="1" cellspacing="1"> <tr bgcolor="white"> <td align="center" colspan="5"> <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> </tr> <% // 获取图书信息集合 List<Book> list = findBook.findAll(); // 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> </tr> <% } } %> </table> </body> </html>
package com.lyq.bean; import java.sql.CallableStatement; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; /** * 查询图书信息 * @author Li YongQiang * */ public class FindBook { /** * 获取数据库连接 * @return Connection对象 */ public Connection getConnection(){ // 数据库连接 Connection conn = null; 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_database11"; // 数据库用户名 String username = "root"; // 数据库密码 String password = "111"; // 创建Connection连接 conn = DriverManager.getConnection(url,username,password); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } // 返回数据库连接 return conn; } /** * 通过存储过程查询数据 * @return List<Book> */ public List<Book> findAll(){ // 实例化List对象 List<Book> list = new ArrayList<Book>(); // 创建数据库连接 Connection conn = getConnection(); try { //调用存储过程 CallableStatement cs = conn.prepareCall("{call findAllBook()}"); // 执行查询操作,并获取结果集 ResultSet rs = cs.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 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")); // 将图书对象添加到集合中 list.add(book); } } catch (Exception e) { e.printStackTrace(); } // 返回list return list; } }
package com.lyq.bean; /** * 图书实体类 * @author Li YongQiang */ 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; } }
<?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>11.7</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> </web-app>
例:MySQL分页查询
package com.lyq.bean; /** * 商品 * @author Li YongQiang * */ public class Product { public static final int PAGE_SIZE = 2; // 编号 private int id; // 名称 private String name; // 价格 private double price; // 数量 private int num; // 单位 private String unit; 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 getNum() { return num; } public void setNum(int num) { this.num = num; } public String getUnit() { return unit; } public void setUnit(String unit) { this.unit = unit; } }
package com.lyq.bean; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.List; /** * 商品数据库操作 * @author Li YongQiang * */ public class BookDao { /** * 获取数据库连接 * @return Connection对象 */ public Connection getConnection(){ // 数据库连接 Connection conn = null; 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_database11"; // 数据库用户名 String username = "root"; // 数据库密码 String password = "111"; // 创建Connection连接 conn = DriverManager.getConnection(url,username,password); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } // 返回数据库连接 return conn; } /** * 分页查询所有商品信息 * @param page 页数 * @return List<Product> */ public List<Product> find(int page){ // 创建List List<Product> list = new ArrayList<Product>(); // 获取数据库连接 Connection conn = getConnection(); // 分页查询的SQL语句 String sql = "select * from tb_product order by id desc limit ?,?"; try { // 获取PreparedStatement PreparedStatement ps = conn.prepareStatement(sql); // 对SQL语句中的第1个参数赋值 ps.setInt(1, (page - 1) * Product.PAGE_SIZE); // 对SQL语句中的第2个参数赋值 ps.setInt(2, Product.PAGE_SIZE); // 执行查询操作 ResultSet rs = ps.executeQuery(); // 光标向后移动,并判断是否有效 while(rs.next()){ // 实例化Product Product p = new Product(); // 对id属性赋值 p.setId(rs.getInt("id")); // 对name属性赋值 p.setName(rs.getString("name")); // 对num属性赋值 p.setNum(rs.getInt("num")); // 对price属性赋值 p.setPrice(rs.getDouble("price")); // 对unit属性赋值 p.setUnit(rs.getString("unit")); // 将Product添加到List集合中 list.add(p); } // 关闭ResultSet rs.close(); // 关闭PreparedStatement ps.close(); // 关闭Connection conn.close(); } catch (SQLException e) { e.printStackTrace(); } return list; } /** * 查询总记录数 * @return 总记录数 */ public int findCount(){ // 总记录数 int count = 0; // 获取数据库连接 Connection conn = getConnection(); // 查询总记录数SQL语句 String sql = "select count(*) from tb_product"; try { // 创建Statement Statement stmt = conn.createStatement(); // 查询并获取ResultSet ResultSet rs = stmt.executeQuery(sql); // 光标向后移动,并判断是否有效 if(rs.next()){ // 对总记录数赋值 count = rs.getInt(1); } // 关闭ResultSet rs.close(); // 关闭Connection conn.close(); } catch (SQLException e) { e.printStackTrace(); } // 返回总记录数 return count; } }
package com.lyq.servlet; import java.io.IOException; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.lyq.bean.Product; import com.lyq.bean.BookDao; /** * Servlet implementation class FindServlet */ public class FindServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 当前页码 int currPage = 1; // 判断传递页码是否有效 if(request.getParameter("page") != null){ // 对当前页码赋值 currPage = Integer.parseInt(request.getParameter("page")); //page-------- } // 实例化ProductDao BookDao dao = new BookDao(); // 查询所有商品信息 List<Product> list = dao.find(currPage); // 将list放置到request之中 request.setAttribute("list", list); // 总页数 int pages ; // 查询总记录数 int count = dao.findCount(); //------------------ // 计算总页数 if(count % Product.PAGE_SIZE == 0){ // 对总页数赋值 pages = count / Product.PAGE_SIZE; }else{ // 对总页数赋值 pages = count / Product.PAGE_SIZE + 1; } // 实例化StringBuffer StringBuffer sb = new StringBuffer(); // 通过循环构建分页条 for(int i=1; i <= pages; i++){ // 判断是否为当前页 if(i == currPage){ // 构建分页条 sb.append("『" + i + "』"); }else{ // 构建分页条 sb.append("<a href='FindServlet?page=" + i + "'>" + i + "</a>"); //参数page-------- } // 构建分页条 sb.append(" "); } // 将分页条的字符串放置到request之中 request.setAttribute("bar", sb.toString()); //bar----------- // 转发到product_list.jsp页面 request.getRequestDispatcher("product_list.jsp").forward(request, response); } }
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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.lyq.bean.Product"%><html> <head> <meta http-equiv="Content-Type" content="text/html; charset=GB18030"> <title>所有商品信息</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="black" cellpadding="1" cellspacing="1"> <tr bgcolor="white"> <td align="center" colspan="5"> <h2>所有商品信息</h2> </td> </tr> <tr align="center" bgcolor="#e1ffc1" > <td><b>ID</b></td> <td><b>商品名称</b></td> <td><b>价格</b></td> <td><b>数量</b></td> <td><b>单位</b></td> </tr> <% List<Product> list = (List<Product>)request.getAttribute("list"); for(Product p : list){ %> <tr align="center" bgcolor="white"> <td><%=p.getId()%></td> <td><%=p.getName()%></td> <td><%=p.getPrice()%></td> <td><%=p.getNum()%></td> <td><%=p.getUnit()%></td> </tr> <% } %> <tr> <td align="center" colspan="5" bgcolor="white"> <%=request.getAttribute("bar")%> </td> </tr> </table> </body> </html>
<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!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>主页</title> </head> <body> <a href="FindServlet">查看所有商品信息</a> </body> </html>
开发模式:
MVC程序设计理念(Model-View-Controller)
视图层:JSP页面。
控制层:Servlet代码。
模型层:JavaBean代码。