java未找到适合jdbc的驱动程序：derby://localhost:1527/prosto

Question

我的库中有驱动器derbyclient.jar，但它仍然找不到我的数据库。我就是无法连接到数据库

String host = "jdbc:derby://localhost:1527/prosto";
String uName = "username";
String uPass = "password";

Connection con = DriverManager.getConnection(host, uName, uPass);

Answer 1

It simole example for you:

    import java.sql.*;

public class FirstExample {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost/EMP";  
//You must use driver, but you can use this driver:
// static String DB_URL = "com.mysql.cj.jdbc.Driver";


   static final String USER = "username";
   static final String PASS = "password";

   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
   try{
      //Register JDBC driver
      Class.forName("com.mysql.jdbc.Driver");

      //Open a connection
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL,USER,PASS);

      //STEP 4: Execute a query
      System.out.println("Creating statement...");
      stmt = conn.createStatement();
      String sql;
      sql = "SELECT id, first, last, age FROM Employees";
      ResultSet rs = stmt.executeQuery(sql);

      //STEP 5: Extract data from result set
      while(rs.next()){
         //Retrieve by column name
         int id  = rs.getInt("id");
         int age = rs.getInt("age");
         String first = rs.getString("first");
         String last = rs.getString("last");

         //Display values
         System.out.print("ID: " + id);
         System.out.print(", Age: " + age);
         System.out.print(", First: " + first);
         System.out.println(", Last: " + last);
      }
      rs.close();
      stmt.close();
      conn.close();
   }catch(SQLException se){
      se.printStackTrace();
   }catch(Exception e){
      e.printStackTrace();
   }finally{

      try{
         if(stmt!=null)
            stmt.close();
      }catch(SQLException se2){
      }// nothing we can do
      try{
         if(conn!=null)
            conn.close();
      }catch(SQLException se){
         se.printStackTrace();
      }//end finally try
   }//end try
   System.out.println("Goodbye!");
}//end main
}


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Answer 2

首先需要加载derby驱动程序类。为此，在DriverManager.getConnection()调用之前添加此代码

try{
    Class.forName("org.apache.derby.jdbc.ClientDriver");// or may be it is "org.apache.derby.jdbc.EmbeddedDriver"? Not sure. Check the correct name and put it here.
} catch(ClassNotFoundException e){
    //handle exception
}

这将在JDBC的驱动程序注册表中加载并注册Derby驱动程序类，之后您将能够连接到数据库

有关更多详细信息，请参阅：

https://db.apache.org/derby/docs/10.4/devguide/cdevdvlp40653.html

Update

derby安装的lib文件夹中应该有一个derbyclient.jar。您还需要将其添加到类路径中，并使其在运行时可用。这似乎解决了我的问题

希望这有帮助