Java JDBC

public class DAO {
    
    //表名
    public static String TABLENAME = "USERLOGIN";
    //创建表
    public static boolean createTable(){
        String sql = "CREATE TABLE "+TABLENAME+"(ID INTEGER PRIMARY KEY AUTO_INCREMENT,NAME VARCHAR(3) NOT NULL,PWD VARCHAR(15) NOT NULL)";
        Connection conn = getConnection();
        
        Statement st = null;
        try {
            st = conn.createStatement();
            int row = st.executeUpdate(sql);
            
            //创建成功，返回受影响的行数，如果为-1，则创建不成功
            System.out.println("创建表成功："+row);
            if(row!=-1){
                return true;
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
            
        
        try {
            st.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return false;
    }
    
    //创建JDBC URL
    static String jdbc = "jdbc:mysql://localhost:3306/student?user=root&password=&characterEncoding=utf-8";
    public static Connection getConnection(){
        
        //加载jdbc驱动
        try {
            //驱动地址全名，包名+类名
            Class.forName("com.mysql.jdbc.Driver");
            
            //连接数据库
            Connection conn = DriverManager.getConnection(jdbc);
            return conn;
//            if(conn!=null){
//                System.out.println("连接成功");
//            }else{
//                System.out.println("连接失败");
////            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
    
    //增  删  改   不带参
    public static boolean 执行(String sql) throws SQLException{
        Connection conn = getConnection();
        Statement statement = conn.createStatement();
        int row = statement.executeUpdate(sql);
        System.out.println("受影响行："+row);
        if(row>0){
            
            return true;
        }
        conn.close();
        return false;
    }
    //增  删  改   带参
    public static boolean 执行(String sql,String[] args) throws SQLException{
        Connection conn = getConnection();
        PreparedStatement pst = conn.prepareStatement(sql);
        for (int i = 0; i < args.length; i++) {
            pst.setString(i+1, args[i]);
        }
        int row = pst.executeUpdate();
        System.out.println("受影响行："+row);
        if(row>0)
            return true;
        conn.close();
        return false;
    }
    
    //查询  不带参
    public static ResultSet 查询(String sql) throws SQLException{
        Connection conn = getConnection();
        Statement st = conn.createStatement();
        ResultSet rs = st.executeQuery(sql);
        conn.close();
        return rs;
    }
    //查询  带参
    public static ResultSet 查询(String sql,String[] args) throws SQLException{
        Connection conn = getConnection();
        PreparedStatement pst = conn.prepareStatement(sql);
        for (int i = 0; i < args.length; i++) {
            pst.setString(i+1, args[i]);
        }
        ResultSet rs = pst.executeQuery();
        conn.close();
        return rs;
    }
    
}

public class User {
    private String id;
    private String name;
    private String pwd;
    private String age;
    private String sex;
    private String sign;

    public User(String name, String pwd) {
        super();
        this.name = name;
        this.pwd = pwd;
    }

    public User(String id, String name, String pwd, String age, String sex,
            String sign) {
        super();
        this.id = id;
        this.name = name;
        this.pwd = pwd;
        this.age = age;
        this.sex = sex;
        this.sign = sign;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", pwd=" + pwd + ", age="
                + age + ", sex=" + sex + ", sign=" + sign + "]";
    }

    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 getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getSign() {
        return sign;
    }

    public void setSign(String sign) {
        this.sign = sign;
    }

}

public interface IUser {
    ResultSet 查询用户(User user);
    
    boolean 注册用户(User user);
    
    boolean 登录用户(User user);
    
    boolean 修改用户(User user,String pwd);
    
    boolean 删除用户(User user);
}

public class UserDAO extends DAO implements IUser{

    
    public UserDAO(){
        createTable();
        
    }
    
    @Override
    public boolean 注册用户(User user) {
        String sql2 = "INSERT INTO "+TABLENAME+"(NAME,PWD) VALUES(?,?)";
        String[] args2 = new String[]{user.getName(),user.getPwd()};
        
        try {
            boolean b = 执行(sql2,args2);
            return b;
        } catch (SQLException e) {
            System.out.println("注册失败");
        }
        return false;
    }

    //查询，然后再遍历
    @Override
    public boolean 登录用户(User user) {
        //根据名字查询
        ResultSet rs = 查询用户(user);
                
        try {
            while(rs.next()){
                String name = rs.getString("NAME");
                String pwd = rs.getString("PWD");
                if(name.equals(user.getName()) && pwd.equals(user.getPwd())){
                    System.out.println("登录成功，欢迎您！"+name);
                    return true;
                }else{
                    System.out.println("登录失败，密码错误");
                    return false;
                }
                
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //查询不到，提示先注册
        System.out.println("登录失败！请先注册");
            
        
        return false;
    }

    @Override
    public boolean 修改用户(User user,String pwd) {
        //用户名不允许修改，只允许修改密码
        String sql = "UPDATE "+TABLENAME+" SET PWD=? WHERE NAME=?";
        String[] args = new String[]{pwd,user.getName()};
        
        try {
            boolean b = 执行(sql,args);
            System.out.println("修改成功！");
            return b;
            
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return false;
    }

    @Override
    public boolean 删除用户(User user) {
        //非管理员，直接删除
        String sql = "DELETE * FROM "+TABLENAME+" WHERE NAME=? AND PWD=?";
        String[] args = new String[]{user.getName(),user.getPwd()};

        try {
            boolean b = 执行(sql,args);
            System.out.println("删除成功");
            return b;
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return false;
    }

    @Override//根据名字查询
    public ResultSet 查询用户(User user) {        
        String sql = "SELECT * FROM "+TABLENAME+" WHERE NAME=?";
        String[] args = new String[]{user.getName()};
        try {        
            ResultSet rs = 查询(sql,args);
            if(rs!=null){
                return rs;
            }

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
    
    
}

public class UserDAOUpadate extends UserDAO{
    
    
    public UserDAOUpadate() {
        super();
    }
    
    //用户注册
    public boolean 用户注册(User user){
        //先查询是否已存在，根据名字
        ResultSet rs = 查询用户(user);
        if(rs==null){
            //不存在，，直接注册
            boolean b = 注册用户(user);
            return b;
        }
        
        return false;
    }
    
    //用户登录,登录成功，返回用户信息
    public void 用户登录(User user){
        if(登录用户(user))        
            System.out.println(user);
        
    }
    
    //修改密码
    public boolean 用户修改密码(User user,String pwd){
        if(登录用户(user)){
            if(pwd.equals(user.getPwd())){
                System.out.println("密码不能与原始密码相同!");
                return false;
            }
            boolean b = 修改用户(user,pwd);
            return b;
        }
        
        return false;
    }
    
    //管理员删除其他账户
    public boolean 用户删除(User user,boolean isDelete){
        //账户是管理员，不允许删除
        if("admin".equals(user.getName())){
            System.out.println("管理员账户无法删除");
            return false;
        }
        //非管理账户直接删除        
        if(isDelete){    
            boolean b = 删除用户(user);
            return b;
        }
        return false;
    }
    
    
    

}