在 Netbeans 中连接 azure 数据库的 Java 程序出现错误

Question

我收到以下错误:

我尝试了各种方法，但出现错误，请参阅以下错误。

run: java.lang.ClassNotFoundException: com.microsoft.sqlserver.jdbc.SQLServerDriver at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:264) at com.sqldbsamples.App.main(App.java:23)

BUILD SUCCESSFUL (total time: 0 seconds)

这是我的代码:请帮助我如何使用 java 程序将我的数据库连接到 azure!!!

public class App {

    public static void main(String[] args) {

        // Connect to database
        String hostName = "testchinnaa.database.windows.net:1433"; // update me
        String dbName = "Test_Gopi"; // update me
        String user = "chinna"; // update me
        String password = "******"; // update me

        String url = String.format("jdbc:sqlserver://testchinnaa.database.windows.net:1433;database=Test_Gopi;user=chinna@testchinna;password=*****;encrypt=true;trustServerCertificate=false;hostNameInCertificate=*.database.windows.net;loginTimeout=30;"
            + "hostNameInCertificate=*.database.windows.net;loginTimeout=30;", hostName, dbName, user, password);
        Connection connection = null;
        try {
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
            connection = DriverManager.getConnection(url);
            String schema = connection.getSchema();
            System.out.println("Successful connection - Schema: " + schema);

            System.out.println("Query data example:");
            System.out.println("=========================================");

            // Create and execute a SELECT SQL statement.
            String selectSql = "SELECT TOP 20 pc.Name as CategoryName, p.name as ProductName "
                + "FROM [SalesLT].[ProductCategory] pc "  
                + "JOIN [SalesLT].[Product] p ON pc.productcategoryid = p.productcategoryid";

            try (Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery(selectSql)) {

                // Print results from select statement
                System.out.println("Top 20 categories:");
                while (resultSet.next())
                {
                    System.out.println(resultSet.getString(1) + " "
                        + resultSet.getString(2));
                }
                connection.close();
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Answer 1

抱歉，您必须弄清楚您使用的是MySql还是MSSql。你说你用的是mysql。但是，在您的连接字符串中，它是一个sqlserver，这意味着它是一个MSSql。

这里是使用java访问数据库的教程:

1. 您需要下载适用于您的数据库的连接器:

   • 对于 MySql:MySQLConnector/J

   • 对于 MSSql:Microsoft JDBC Driver for SQLServer

2. 手动将连接器 jar 文件添加到类路径中。或者您可以使用 Maven 依赖项管理器在项目中安装和配置 Connector/J 库。

   <!-- Example for mysql -->
   <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.18</version>
   </dependency>
   

3. 代码示例

   • 对于 MSSql:

     try {
         Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver").newInstance();
         connection = DriverManager.getConnection("conntection_string");
         String SQL = "SELECT name FROM sysdatabases;";
     
         try (Statement statement = connection.createStatement();
              ResultSet resultSet = statement.executeQuery(SQL)) {
     
             // Print results from select statement
             while (resultSet.next()) {
                 System.out.println(resultSet.getString(1));
             }
             connection.close();
         }
     } catch (Exception e) {
         e.printStackTrace();
     }
     

   • 对于 MySql:

     Connection conn = null;
     ResultSet rs = null;
     try {
         Class.forName("com.mysql.cj.jdbc.Driver");
         String connectionUrl = "jdbc:mysql://{server_name}.mysql.database.azure.com:3306?useSSL=true&requireSSL=false&serverTimezone=UTC";;
         conn = DriverManager.getConnection(connectionUrl, "username_from_portal, like: jack@mysqldemo258", "password");
         rs = conn.prepareStatement("show databases").executeQuery();
     
         while(rs.next()){
             System.out.println(rs.getString(1));
         }
     } catch (ClassNotFoundException e) {
         e.printStackTrace();
     } catch (SQLException e) {
         e.printStackTrace();
     } finally {
         try{
             if(rs != null) rs.close();
             if(conn != null) conn.close();
         } catch (SQLException e) {
             e.printStackTrace();
         }
     }