Java-JDBC操作

一、不使用注入方法

public void login(String username, String password) throws ClassNotFoundException, SQLException {
// 1.注册驱动
Class.forName("com.mysql.jdbc.Driver");
// 2.获取连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/数据库名", "root", "root");
// 3.创建执行sql语句的对象
Statement stmt = conn.createStatement();
// 4.书写一个sql语句
String sql = "select * from tbl_user where " + "uname='" + username + "' and upassword='" + password + "'";
// 5.执行sql语句
ResultSet rs = stmt.executeQuery(sql);
// 6.对结果集进行处理
if (rs.next()) {
System.out.println("恭喜您，" + username + ",登录成功!");
System.out.println(sql);
} else {
System.out.println("账号或密码错误!");
}
//7.关闭
if (rs != null)
rs.close();
if (stmt != null)
stmt.close();
if (conn != null)
conn.close();
}

二、使用注入方法

public void login1(String username, String password) throws ClassNotFoundException, SQLException {
// 1.注册驱动
Class.forName("com.mysql.jdbc.Driver");
// 2.获取连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/数据库名", "root", "root");
// 3.编写sql语句
String sql = "select * from tbl_user where uname=? and upassword=?";
// 4.创建预处理对象
PreparedStatement pstmt = conn.prepareStatement(sql);
// 5.设置参数(给占位符)
pstmt.setString(1, username);
pstmt.setString(2, password);
// 6.执行查询操作
ResultSet rs = pstmt.executeQuery();
// 7.对结果集进行处理
if (rs.next()) {
System.out.println("恭喜您，" + username + ",登录成功!");
System.out.println(sql);
} else {
System.out.println("账号或密码错误!");
}
//8.关闭
if (rs != null)
rs.close();
if (pstmt != null)
pstmt.close();
if (conn != null)
conn.close();
}