Java任务：修改用户密码
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任务描述：修改用户密码
如图7-2所示，用户登录成功后还可以根据需要选择自己需要的服务，如修改密码，查询图书等。本节先来完成密码修改，下节内容将完成图书查询。
图7-2 修改密码
前情回顾
用户数据接口UserDao
package dao;
import entity.User;
public interface UserDao {
public void addUser(User u);//添加用户
public void queryUser( );//查询用户
public boolean hasUser(String name);//查询某个用户是否存在
public boolean verify(String name, String pwd);//验证用户名和密码是否一致
}
实现思路
- 我们之前已经定义了一个UserDao接口。
- 现在我们用MYSQL数据库来实现这个接口。
任务实现
创建测试数据
接下来我们在 MySQL 中创建 cloud 数据库，并创建 user 数据表，表结构如下：
mysql> create database cloud;
Query OK, 1 row affected (0.00 sec)
mysql> use cloud;
Database changed
mysql> CREATE TABLE IF NOT EXISTS `user`(
`id` INT UNSIGNED AUTO_INCREMENT,
`name` VARCHAR(100) NOT NULL,
`password` VARCHAR(40) NOT NULL,
PRIMARY KEY ( `id` )
)ENGINE=InnoDB DEFAULT CHARSET=utf8;
mysql> CREATE UNIQUE INDEX uname on user(name);
Query OK, 0 rows affected (0.25 sec)
Records: 0 Duplicates: 0 Warnings: 0
插入一些数据：
mysql> INSERT INTO `user` (name,password) VALUES ('ma', '123456');
Query OK, 1 row affected (0.12 sec)
mysql> INSERT INTO `user` (name,password) VALUES ('ma', '123457');
ERROR 1062 (23000): Duplicate entry 'ma' for key 2
</nowiki>
程序代码
package dao;
import java.sql.*;
import entity.User;
public class UserDaoSQL implements UserDao{
// JDBC 驱动名及数据库 URL
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost:3306/cloud?characterEncoding=utf8";
// 数据库的用户名与密码，需要根据自己的设置
static final String USER = "root";
static final String PASS = "000000";
public UserDaoSQL(){
}
/**
* 连接数据库
* @param 值为空
* @return Connection 建立的数据库连接
*/
private static Connection getConn() {
Connection conn = null;
try {
Class.forName(JDBC_DRIVER); //classLoader,加载对应驱动
conn = (Connection) DriverManager.getConnection(DB_URL, USER, PASS);
System.out.println("MySQL连接成功！");
} catch (ClassNotFoundException e) {
System.out.println(e.getMessage());
} catch (SQLException e) {
System.out.println(e.getMessage());
}
return conn;
}
/**
* 向数据库中添加用户
* @param user,要添加的用户
* @return 返回值为空
*/
public void addUser(User user){//添加用户
Connection conn = getConn();
String sql = "insert into user (name,password) values(?,?)";
PreparedStatement pstmt;
try {
pstmt = (PreparedStatement) conn.prepareStatement(sql);
pstmt.setString(1, user.getName());
pstmt.setString(2, user.getPassword()); //pstmt.setInt(2, user.getAge()); pstmt.setDate
pstmt.executeUpdate();
pstmt.close();
conn.close();
} catch (SQLException e) {
System.out.println(e.getMessage());
}
}
/**
* 向数据库中查询所有用户
* @param 值为空
* @return 值为空
*/
public void queryUser( ){//查询用户
Connection conn = getConn();
String sql = "select * from user";
PreparedStatement pstmt;
try {
pstmt = (PreparedStatement)conn.prepareStatement(sql);
ResultSet rs = pstmt.executeQuery();//执行查询
int col = rs.getMetaData().getColumnCount();//获取字段数
System.out.println("============================");
while (rs.next()) {
for (int i = 1; i <= col; i++) {
System.out.print(rs.getString(i) + "\t");
if ((i == 2) && (rs.getString(i).length() < 8)) {//此行仅仅是为了显示更好看，可以删去
System.out.print("\t");
}
}
System.out.println("");
}
System.out.println("============================");
} catch (SQLException e) {
System.out.println(e.getMessage());
}
}
/**
* 验证用户名是否存在
* @param name,用户名
* @return 布尔值
*/
public boolean hasUser(String name){//查询某个用户是否存在
boolean success=false;//标记验证是否成功
try {
Connection con = getConn();
String sql = "select * from user where name=? ";
PreparedStatement pstmt = (PreparedStatement) con.prepareStatement(sql);
pstmt.setString(1, name);
ResultSet rs = pstmt.executeQuery();//执行查询
if(rs.next()) {
//System.out.println("欢迎" + rs.getString("name"));
success=true;
}
pstmt.close();
con.close();
}catch (SQLException e) {
System.out.println(e.getMessage());
}
return success;
}
/**
* 验证用户名和密码是否正确
* @param usename,用户名
* @param password，密码
* @return 建立的数据库连接
*/
public boolean verify(String username, String password) {
boolean success=false;//标记验证是否成功
try {
Connection con = getConn();
String sql = "select * from user where name=? and password=?";
PreparedStatement pstmt = (PreparedStatement) con.prepareStatement(sql);
pstmt.setString(1, username);
pstmt.setString(2, password);
ResultSet rs = pstmt.executeQuery();//执行查询
if(rs.next()) {
//System.out.println("欢迎" + rs.getString("name"));
success=true;
}
pstmt.close();
con.close();
}catch (SQLException e) {
System.out.println(e.getMessage());
}
return success;
}
public static void main(String[] args) {
getConn();
UserDaoSQL uds =new UserDaoSQL();
uds.verify("ma","123456");
User u1=new User("zhangyi","456");//这里可能会遇到构造方法参数不符的问题，重新修改一下构造方法
uds.addUser(u1);
System.out.println(uds.hasUser(u1.getName()));
uds.queryUser();
System.out.println("Goodbye!");
}
}
其他类
User类：
package entity;
import service.*;
public class User {
private String id; //用户登录账号
private String name; //用户名-真实姓名
private String password;//用户登录密码
private CartService cart = new CartService(); //用户的购物车
/**
* 无参构造函数
*/
public User() {
}
/**
* 带参构造函数
*
*
* @param name
* @param password
*/
public User(String name, String password) {
this();
this.name = name;
this.password = password;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public CartService getCart() {
return cart;
}
@Override
public String toString() {
return "用户编号：" + this.id +
" | 用户姓名：" + this.name;
}
}
返回 Java程序设计
