再会！
我知道这类问题有很多帖子，但我查看了其中一些帖子，但由于我使用的是嵌入式 Derby，因此找不到我的问题的答案。
我收到此错误：
##THIS IS GENERATED BY THE METHOD printSQLException shown at the code below
----- SQLException -----
SQL State: 08001
Error Code: 0
Message: No suitable driver found for jdbc:derby://localhost:1527/recordbookDB
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at recordbook.RecordBook.checkHasAccount(RecordBook.java:71)
at recordbook.Login.<init>(Login.java:31)
at recordbook.Login$1.run(Login.java:168)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:226)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:647)
at java.awt.EventQueue.access$000(EventQueue.java:96)
at java.awt.EventQueue$1.run(EventQueue.java:608)
at java.awt.EventQueue$1.run(EventQueue.java:606)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:105)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:617)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:275)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:200)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:185)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:177)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:138)
BUILD STOPPED (total time: 6 minutes 16 seconds)
问题在于连接到数据库部分。这是查看问题所需的代码（和方法）的一部分：
public class RecordBook
{
private String framework = "embedded";
private String driver = "org.apache.derby.jdbc.EmbeddedDriver";
private String protocol = "jdbc:derby:";
private Connection conn;
//this is where everything happens
public RecordBook()
{
//Loading the Driver
loadDriver();
//Connecting to the database
conn = null;
try
{
Properties props = new Properties();
props.put("user","root");
props.put("password","root");
String dbName = "//localhost:1527/recordbookDB";
conn = DriverManager.getConnection(protocol + dbName, props); //error is here
}
catch (SQLException sqle)
{
printSQLException(sqle);
}
}
//BELOW ARE THE METHODS USED ABOVE
/**
* CODE FROM http://db.apache.org/derby/papers/DerbyTut/embedded_intro.html
*/
private void loadDriver()
{
try
{
Class.forName(driver).newInstance();
System.out.println("Loaded the appropriate driver");
}
catch (ClassNotFoundException cnfe)
{
System.err.println("\nUnable to load the JDBC driver " + driver);
System.err.println("Please check your CLASSPATH.");
cnfe.printStackTrace(System.err);
}
catch (InstantiationException ie)
{
System.err.println("\nUnable to instantiate the JDBC driver " + driver);
ie.printStackTrace(System.err);
}
catch (IllegalAccessException iae)
{
System.err.println("\nNot allowed to access the JDBC driver " + driver);
iae.printStackTrace(System.err);
}
}
/**
* CODE FROM http://db.apache.org/derby/papers/DerbyTut/embedded_intro.html
*
* @param e the SQLException from which to print details.
*/
public static void printSQLException(SQLException e)
{
// Unwraps the entire exception chain to unveil the real cause of the exception.
while (e != null)
{
System.err.println("\n----- SQLException -----");
System.err.println(" SQL State: " + e.getSQLState());
System.err.println(" Error Code: " + e.getErrorCode());
System.err.println(" Message: " + e.getMessage());
// for stack traces, refer to derby.log or uncomment this:
//e.printStackTrace(System.err);
e = e.getNextException();
}
}