1. 此案例以帐号密码后台更新维护为例子，对数据库调取数据更新流程进行演示：
代码示例：
<%@page import="java.io.IOException"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ page import="java.sql.*" %>
<!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>SQLOper_Demo</title>
</head>
<body>
<%!
/*数据库初始化样例代码段*/
int flag = 0;
String username = "";
String password = "";
String sql_demo = "";
PreparedStatement pres = null;
public static Connection getConn(JspWriter out) throws IOException {
String url = "jdbc:mysql://localhost:3306/user";
String username = "root";
String password = "admin";
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver"); //classLoader,加载对应驱动
conn = (Connection) DriverManager.getConnection(url, username, password);
}catch(ClassNotFoundException e){
out.println("数据库组件查找异常！！");
e.printStackTrace();
}catch(SQLException e){
out.println("数据库操作异常!!");
e.printStackTrace();
}
return conn;
}
%>
<%
/*参数接收以及判断流程代码段*/
try{
username = request.getParameter("username");
password = request.getParameter("password");
}catch(Exception e){
out.println("参数接收异常");
e.printStackTrace();
}
try{
Connection conn = getConn(out);
if(conn == null){
out.println("连接异常!");
}else{
sql_demo = "update userinfo set username=?,password=?";
pres = conn.prepareStatement(sql_demo);
pres.setString(1, username);
pres.setString(2,password);
pres.executeUpdate();
if(flag == 1){
out.println("帐户更新成功!!"+"<br>");
}else{
out.println("帐户更新失败!!"+"<br>");
}
pres.close();
conn.close();
}
}catch(SQLException e){
out.print("帐户更新出现异常!!");
e.printStackTrace();
}
%>
</body>
</html>2. 此案例以帐号密码后端登录验证的例子，对数据库的数据取出流程进行演示：
代码示例：
<%@page import="java.io.IOException"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<%@ page import="java.sql.*" %>
<!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>Requests</title>
</head>
<body>
<%!
/*数据库初始化样例代码段*/
String username = "";
String password = "";
String correct_password = "";
String sql_Request = "";
PreparedStatement pres = null;
ResultSet res = null;
public static Connection getConn(JspWriter out) throws IOException {
String url = "jdbc:mysql://localhost:3306/user";
String username = "root";
String password = "admin";
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver"); //classLoader,加载对应驱动
conn = (Connection) DriverManager.getConnection(url, username, password);
}catch(ClassNotFoundException e){
out.println("数据库组件查找异常！！");
e.printStackTrace();
}catch(SQLException e){
out.println("数据库操作异常!!");
e.printStackTrace();
}
return conn;
}
%>
<%
/*帐号密码验证代码段*/
try{
username = request.getParameter("username");
password = request.getParameter("password");
}catch(Exception e){
out.println("参数接收异常");
e.printStackTrace();
}
try{
Connection conn = getConn(out);
if(conn == null){
out.println("连接异常!");
}else{
sql_Request = "select password from userinfo where username=?";
pres = conn.prepareStatement(sql_Request);
pres.setString(1, username);
res = pres.executeQuery();
while(res.next()){
correct_password = res.getString(1);
}
pres.close();
conn.close();
}
if(password.equals(correct_password)){
out.println("Login Successful !! <br><br> Please wait for 3 seconds...");
out.println("<meta http-equiv='refresh' content="3;url='Oper.jsp'">s ");
}else{
out.println("Login Failed !! <br><br> Please wait for 3 seconds...");
out.println(" <meta http-equiv='refresh' content="3;url='index.html'"> ");
}
}catch(SQLException e){
out.print("帐户检索失败！！ 请查证后在试！！");
e.printStackTrace();
}
%>
</body>
</html>