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我目前正在學習Java中的一些DataBase技巧，並且我發現了我正在閱讀的這本好書。 在某些時候，ITE鼓勵我去嘗試下面的類手動數據庫連接：HSQL驅動不工作？
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class DemoSelect {
public static void main (String[] args){
//Connection parameters
String usr = "sa";
String pwd = "";
String driver = "org.hsqldb.jdbcDriver";
String url = "jdbc:hsqldb:hsql://localhost/xdb";
Connection con = null;
PreparedStatement pstm = null;
ResultSet rs = null;
try{
//Starting up the driver
Class.forName(driver);
//Conecting
con = DriverManager.getConnection (url,usr,pwd);
//Writting a query
String sql = "SELECT empno, ename, hiredate, deptno FROM emp";
//Setting up the SQL statement
pstm = con.prepareStatement(sql);
//Execute the SQL query
rs = pstm.executeQuery();
//Iterating the results
while (rs.next()){
//Simple method to show the data
System.out.print(rs.getInt("empno")+", ");
System.out.print(rs.getString("ename")+ ", ");
System.out.print(rs.getDate("hiredate")+", ");
System.out.println(rs.getInt("deptno"));
}
}catch (Exception e){
e.printStackTrace();
throw new RuntimeException(e);
}finally{
try{
//Closing all the opened resources
if (rs!=null) rs.close();
if (pstm!=null) pstm.close();
if (con!=null) con.close();
}catch (Exception e){
e.printStackTrace();
throw new RuntimeException(e);
}
}
}
}
但是當我嘗試運行它，它在下面的描述產生一個錯誤：
java.lang.ClassNotFoundException: org.hsqldb.jdbcDriver
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:186)
at cap3.jdbc.DemoSelect.main(DemoSelect.java:25)
Exception in thread "main" java.lang.RuntimeException: java.lang.ClassNotFoundException: org.hsqldb.jdbcDriver
at cap3.jdbc.DemoSelect.main(DemoSelect.java:53)
Caused by: java.lang.ClassNotFoundException: org.hsqldb.jdbcDriver
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:186)
at cap3.jdbc.DemoSelect.main(DemoSelect.java:25)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)`
我可能會錯過什麼？
我使用的是NetBeans，我下載了HSQL驅動程序。我設法.jar文件導入到庫，我得到了以下錯誤代碼：
java.sql.SQLTransientConnectionException: java.net.ConnectException: Connection refused: connect
at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCConnection.<init>(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.getConnection(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:579)
at java.sql.DriverManager.getConnection(DriverManager.java:221)
at cap3.jdbc.DemoSelect.main(DemoSelect.java:28)
Caused by: org.hsqldb.HsqlException: java.net.ConnectException: Connection refused: connect
at org.hsqldb.ClientConnection.openConnection(Unknown Source)
at org.hsqldb.ClientConnection.initConnection(Unknown Source)
at org.hsqldb.ClientConnection.<init>(Unknown Source)
... 6 more
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:69)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:337)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:198)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:180)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391)
at java.net.Socket.connect(Socket.java:579)
at java.net.Socket.connect(Socket.java:528)
at java.net.Socket.<init>(Socket.java:425)
at java.net.Socket.<init>(Socket.java:208)
at org.hsqldb.server.HsqlSocketFactory.createSocket(Unknown Source)
... 9 more
Exception in thread "main" java.lang.RuntimeException: java.sql.SQLTransientConnectionException: java.net.ConnectException: Connection refused: connect
at cap3.jdbc.DemoSelect.main(DemoSelect.java:53)
Caused by: java.sql.SQLTransientConnectionException: java.net.ConnectException: Connection refused: connect
at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
at org.hsqldb.jdbc.JDBCConnection.<init>(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.getConnection(Unknown Source)
at org.hsqldb.jdbc.JDBCDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:579)
at java.sql.DriverManager.getConnection(DriverManager.java:221)
at cap3.jdbc.DemoSelect.main(DemoSelect.java:28)
Caused by: org.hsqldb.HsqlException: java.net.ConnectException: Connection refused: connect
at org.hsqldb.ClientConnection.openConnection(Unknown Source)
at org.hsqldb.ClientConnection.initConnection(Unknown Source)
at org.hsqldb.ClientConnection.<init>(Unknown Source)
... 6 more
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:69)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:337)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:198)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:180)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391)
at java.net.Socket.connect(Socket.java:579)
at java.net.Socket.connect(Socket.java:528)
at java.net.Socket.<init>(Socket.java:425)
at java.net.Socket.<init>(Socket.java:208)
at org.hsqldb.server.HsqlSocketFactory.createSocket(Unknown Source)
... 9 more
Java Result: 1
BUILD SUCCESSFUL (total time: 1 second)
有問題嗎？ –
請看我昨天的回覆以及1）確保HSQL已安裝並正在運行（我提供了鏈接），並且2）確保HSQL JDBC .jar文件在您的路徑/項目中。丟失的.jar文件是堆棧跟蹤的原因。 – paulsm4