10.3.2 查询数据
10.3.3 修改数据
10.3.4 删除数据
ShowBook.jsp此页面包含查询、修改、删除
微信截图_20190828113259.png
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@page import="com.hwp.bean.Book"%>
查询、修改、删除
所有图书信息
ID
图书名称
价格
数量
作者
修改数量
删除
<%
List list = (List) request.getAttribute("list");
if (list == null || list.size() < 1) {
} else {
for (int i = 0; i < list.size(); i++) {
Book _book = list.get(i);
%>
<%=_book.getId()%>
<%=_book.getName()%>
<%=_book.getPrice()%>
<%=_book.getBookCount()%>
<%=_book.getAuthor()%>
<%
}
}
%>
UpdateCountServlet.java修改bookCount数量
@WebServlet("/UpdateCountServlet")
public class UpdateCountServlet extends HttpServlet{
/**
*
*/
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
super.doGet(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
int id=Integer.valueOf(req.getParameter("id"));
int bookCount=Integer.valueOf(req.getParameter("bookCount"));
try{
Class.forName("com.mysql.jdbc.Driver"); //加载数据库驱动
String password="hwp123456"; //数据库密码
String user="root"; //数据库账号
String url="jdbc:mysql://localhost:3306/book"; //数据库连接字符串
Connection conn = DriverManager.getConnection(url, user, password);//创建Connection连接
String sql="update book_info set bookCount=? where id=? "; //更新SQL语句
PreparedStatement ps= (PreparedStatement) conn.prepareStatement(sql); 获取PreparedStatement对象
ps.setInt(1, bookCount); //对sql语句中的参数1赋值
ps.setInt(2, id); //对sql语句中的参数2赋值
ps.executeUpdate(); //执行更新操作
ps.close(); //关闭PreparedStatement
conn.close(); //关闭 Connection
}catch(Exception e){
e.printStackTrace();
}
resp.sendRedirect("FindServlet"); //重定向到FindServlet
}
}
DeleteServlet.java删除条目
@WebServlet("/DeleteServlet")
public class DeleteServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
super.doGet(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
int id=Integer.valueOf(req.getParameter("id")); //获取图书ID
try{
Class.forName("com.mysql.jdbc.Driver"); //加载数据库驱动
String password="hwp123456"; //数据库密码
String user="root"; //数据库用户名
String url="jdbc:mysql://localhost:3306/book"; //数据库连接字符串
Connection conn = DriverManager.getConnection(url, user, password);//创建Connection连接
String sql="delete from book_info where id=? "; //删除图书信息的SQL语句
//String sql="select*from book_info";
PreparedStatement ps= (PreparedStatement) conn.prepareStatement(sql); //获取PreparedStatement对象
ps.setInt(1, id); //对sql语句中的第一个占位符赋值
ps.executeUpdate(); //执行更新操作
ps.close(); //关闭 PreparedStatement
conn.close(); //关闭 Connection
}catch(Exception e){
e.printStackTrace();
}
resp.sendRedirect("FindServlet"); //重定向到FindServlet
}
}
10.3.5 批处理
-
1.创建数据库表 表结构(如图)
微信截图_20190828143016.png 2.创建
Batch.java类
public class Batch {
/**
* 获取 Connection对象
* @return
*/
public Connection getConnection() {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
//解决中文乱码
String url = "jdbc:mysql://localhost:3306/book?characterEncoding=utf-8";
String user = "root";
String password = "hwp123456";
conn = DriverManager.getConnection(url, user, password);
} catch (Exception e) {
e.printStackTrace();
}
return conn;
}
/**
* 保存数据
* @return
*/
public int save() {
int row = 0;
Connection conn = getConnection();
try {
String sql = "insert into tb_studnet_batch(name,sex,age)values(?,?,?)";
PreparedStatement ps = conn.prepareStatement(sql);
Random random = new Random();
for (int i = 0; i < 10; i++) {
ps.setString(1, "名字" + (i + 1));
ps.setString(2, i % 2 == 0 ? "男" : "女");
ps.setInt(3, random.nextInt(5) + 10);
ps.addBatch();
}
int[] rows = ps.executeBatch();
row = rows.length;
ps.close();
conn.close();
} catch (Exception e) {
e.printStackTrace();
}
return row;
}
}
PreparedStatement对象的批处理操作调用的是executeBatch()而不是executeUpdate()方法或者execute()方法
- 3.创建
students_add.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
批量操作
This is my JSP page.