java - j2ee 从数据库中选择数据不起作用

Question

我尝试在 j2ee 中创建一个登录页面。在servlet中。我尝试使用选择查询检查数据库的输入值，但结果为假。所以我尝试喜欢在数据库表中输入值，但它仍然是错误的。即使我的用户表数据完全相同，输出仍然为假。请我需要解决这个问题，我被困住了

Answer 1

I tried this code worked for me

Mysql 8 Connector

Avoid class.forName() it is optional password is missing in your connection please check the code below

`public static void main(String[] args) { //1. 创建连接字符串 String url = "jdbc:mysql://localhost:3306/test"; //2. 添加用户凭证 字符串用户名=“root”； 字符串密码=“”； String sql = "SELECT * FROM users WHERE username=? AND password=?;";

    try(Connection con = DriverManager.getConnection(url, username, password);
        PreparedStatement statement = con.prepareStatement(sql);
        ){
    // 3. JDBC CONNECTIONS
        statement.setString(1, "test");
        statement.setString(2, "test123");
    // 4. STATEMENT FROM CONNECTION
        ResultSet rs = statement.executeQuery();
    // 5. GET RESULT SET FROM STATEMENT
        System.out.println(rs.next());


    }catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    // 6. CLOSE ALL THE CONNECTIONS

}`