一、需求
在Servlet中可以使用JDBC技术访问数据库，常见功能如下：
- 查询DB数据，然后生成显示页面，例如：列表显示功能。
- 接收请求参数，然后对DB操作，例如：注册、登录、修改密码等功能。
二、代码演示
1、编写注册界面
-
创建空工程，在工程中创建javaEE模块
-
配置中设置tomcat的部署
-
编写register界面
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>简单注册界面</title> </head> <body> <form action="register" method="post"> 用户名：<input type="text" name="userName"/><br> 密码：<input type="text" name="password"><br> <input type="submit" value="注册"> </form> </body> </html>
2、编写Servlet 获取注册信息
- 编写servlet
- RegisterServlet
```java
package com.example.register_demo01;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
public class RegisterServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1、获取请求的用户名和密码
String userName = request.getParameter("userName");
System.out.println("获取到的用户名为：" + userName);
String password = request.getParameter("password");
System.out.println("获取到的密码为：" + password);
}
}
```
-
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> <servlet> <servlet-name>RegisterServlet</servlet-name> <servlet-class>com.example.register_demo01.RegisterServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>RegisterServlet</servlet-name> <url-pattern>/register</url-pattern> </servlet-mapping> </web-app>
-
部署测试：
-
运行tomcat
-
访问注册界面，发送注册请求，tomcat获取注册信息
-
3、 创建原始User类
package com.example.register_demo01.pojo;
public class User {
private int id;
private String userName;
private String password;
public User(){}
public User(String userName, String password) {
this.userName = userName;
this.password = password;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", userName='" + userName + '\'' +
", password='" + password + '\'' +
'}';
}
}
4、创建数据库
5、创建DbUtil，使用jdbc控制数据库
代码：
package com.example.register_demo01.utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class DbUtil {
private static String jdbcName;
private static String dbUrl;
private static String dbUserName;
private static String dbPassword;
//静态初始化操作
static {
jdbcName = "com.mysql.jdbc.Driver";
dbUrl = "jdbc:mysql://localhost:3306/db_web";
dbUserName = "root";
dbPassword = "root";
try {
Class.forName(jdbcName);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public static Connection getConnection() throws SQLException {
Connection connection = DriverManager.getConnection(dbUrl, dbUserName, dbPassword);
return connection;
}
public static void closeConnection(Connection con) throws SQLException {
if (null != con){
con.close();
}
}
}
6、编写UserDao，将User对象存储到数据库
代码：
package com.example.register_demo01.dao;
import com.example.register_demo01.pojo.User;
import com.example.register_demo01.utils.DbUtil;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
public class UserDao {
public int createUser(User user) {
Connection connection = null;
PreparedStatement preparedStatement = null;
try {
//1、获取连接
Connection connection1 = DbUtil.getConnection();
//2、准备sql
String sql = "insert into t_user values(null, ?, ?)";
//3、获取PreparedStatement
preparedStatement = connection.prepareStatement(sql);
//4、向问号位置设置数据
preparedStatement.setString(1, user.getUserName());
preparedStatement.setString(2, user.getPassword());
//5、执行sql
int row = preparedStatement.executeUpdate();
return row;
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
//6、关闭资源
try {
DbUtil.closeConnection(connection);
if(preparedStatement != null){
preparedStatement.close();
}
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
return -1;//执行失败
}
}
7、修改Servlet，添加保存进数据库的操作
-
代码：
package com.example.register_demo01; import com.example.register_demo01.dao.UserDao; import com.example.register_demo01.pojo.User; import javax.servlet.*; import javax.servlet.http.*; import java.io.IOException; import java.io.PrintWriter; public class RegisterServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1、获取请求的用户名和密码 String userName = request.getParameter("userName"); System.out.println("获取到的用户名为：" + userName); String password = request.getParameter("password"); System.out.println("获取到的密码为：" + password); //2、封装user信息，将信息保存到数据库 User user = new User(userName, password); UserDao userDao = new UserDao(); int res = userDao.createUser(user); //3、将处理结果响应到浏览器 response.setContentType("text/html;charset=utf-8"); PrintWriter writer = response.getWriter(); if (1 == res){ System.out.println("注册成功"); writer.write("<h1>注册成功！</h1>"); }else { System.out.println("注册失败"); writer.write("<h1>注册失败！</h1>"); } writer.close(); } } -
测试结果：
