7

首先，这是我第一次使用 Apache Derby。我正在使用 netbeans，愿意使用嵌入式 apache derby，并按照以下教程配置和安装数据库。然后，我使用项目属性将 derby.jar 文件附加到我的项目中。

http://netbeans.org/kb/docs/ide/java-db.html#starting

附图将在 netbeans 中显示我的数据库状态 在此处输入图像描述

我的数据库名称是“联系人”。表名是“朋友”。

以下是我的测试代码

**DatabaseConnector.java**

import java.sql.*;

public class DataBaseConnector
{
    private Connection con;

    public DataBaseConnector()
    {

    }

    private void createConnection()
    {
        try
        {
            Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
            con = DriverManager.getConnection("jdbc:derby:C:/Users/yohan/.netbeans-derby/contact","yohan","xyz");
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }

    private void closeConnection()
    {
        try
        {
            con.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }


    public void insertData(int id, String firstName, String lastName)
    {
        createConnection();
        try
        {
            PreparedStatement ps = con.prepareStatement("insert into FRIENDS values(?,?,?)");
            ps.setInt(1, id);
            ps.setString(1, firstName);
            ps.setString(2, lastName);

            int result = ps.executeUpdate();

            if(result>0)
            {
                System.out.println("Data Inserted");
            }
            else
            {
                System.out.println("Something happened");
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            closeConnection();
        }
    }


}

数据库UI.java

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;

public class DatabaseUI extends JFrame
{
    private JLabel firstName, id, lastName;
    private JTextField idTxt, firstNameTxt, lastNameTxt;
    private JButton ok;

    public DatabaseUI()
    {
     firstName = new JLabel("First Name: ");
     lastName = new JLabel("Last Name: ");
     id = new JLabel("ID: ");

     firstNameTxt = new JTextField(10);
     lastNameTxt = new JTextField(10);
     idTxt = new JTextField(10);

     ok = new JButton("OK");
     ok.addActionListener(new OKAction());

     JPanel centerPanel = new JPanel();
     centerPanel.setLayout(new GridLayout(4,2));
     centerPanel.add(id);
     centerPanel.add(idTxt);
     centerPanel.add(firstName);
     centerPanel.add(firstNameTxt);
     centerPanel.add(lastName);
     centerPanel.add(lastNameTxt);
     centerPanel.add(new JPanel());
     centerPanel.add(ok);

     getContentPane().add(centerPanel,"Center");


     this.pack();
     this.setVisible(true);


    }

    private class OKAction implements ActionListener
    {
        public void actionPerformed(ActionEvent ae)
        {
            DataBaseConnector db = new DataBaseConnector();

            int id = Integer.parseInt(idTxt.getText());

            db.insertData(id, firstNameTxt.getText().trim(), lastNameTxt.getText().trim());
        }
    }

    public static void main(String[]args)
    {
        new DatabaseUI();
    }
}

但是，当我尝试将数据插入数据库时​​，它给了我以下错误

run:
java.sql.SQLException: Failed to start database 'C:/Users/yohan/.netbeans-derby/contact' with class loader sun.misc.Launcher$AppClassLoader@1050169, see the next exception for details.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.seeNextException(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.bootDatabase(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection30.<init>(Unknown Source)
    at org.apache.derby.impl.jdbc.EmbedConnection40.<init>(Unknown Source)
    at org.apache.derby.jdbc.Driver40.getNewEmbedConnection(Unknown Source)
    at org.apache.derby.jdbc.InternalDriver.connect(Unknown Source)
    at org.apache.derby.jdbc.AutoloadedDriver.connect(Unknown Source)
    at java.sql.DriverManager.getConnection(DriverManager.java:579)
    at java.sql.DriverManager.getConnection(DriverManager.java:221)
    at DataBaseConnector.createConnection(DataBaseConnector.java:17)
    at DataBaseConnector.insertData(DataBaseConnector.java:40)
    at DatabaseUI$OKAction.actionPerformed(DatabaseUI.java:53)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6504)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6269)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4860)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2713)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
    at java.awt.EventQueue.access$000(EventQueue.java:101)
    at java.awt.EventQueue$3.run(EventQueue.java:666)
    at java.awt.EventQueue$3.run(EventQueue.java:664)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:680)
    at java.awt.EventQueue$4.run(EventQueue.java:678)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
Caused by: java.sql.SQLException: Failed to start database 'C:/Users/yohan/.netbeans-derby/contact' with class loader sun.misc.Launcher$AppClassLoader@1050169, see the next exception for details.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)
    ... 51 more
Caused by: java.sql.SQLException: Another instance of Derby may have already booted the database C:\Users\yohan\.netbeans-derby\contact.
    at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)
    at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)
    at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Unknown Source)
    ... 48 more
Caused by: ERROR XSDB6: Another instance of Derby may have already booted the database C:\Users\yohan\.netbeans-derby\contact.
    at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
    at org.apache.derby.impl.store.raw.data.BaseDataFileFactory.privGetJBMSLockOnDB(Unknown Source)
    at org.apache.derby.impl.store.raw.data.BaseDataFileFactory.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.apache.derby.impl.store.raw.data.BaseDataFileFactory.getJBMSLockOnDB(Unknown Source)
    at org.apache.derby.impl.store.raw.data.BaseDataFileFactory.boot(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.boot(Unknown Source)
    at org.apache.derby.impl.services.monitor.TopService.bootModule(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.startModule(Unknown Source)
    at org.apache.derby.iapi.services.monitor.Monitor.bootServiceModule(Unknown Source)
    at org.apache.derby.impl.store.raw.RawStore.boot(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.boot(Unknown Source)
    at org.apache.derby.impl.services.monitor.TopService.bootModule(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.startModule(Unknown Source)
    at org.apache.derby.iapi.services.monitor.Monitor.bootServiceModule(Unknown Source)
    at org.apache.derby.impl.store.access.RAMAccessManager.boot(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.boot(Unknown Source)
    at org.apache.derby.impl.services.monitor.TopService.bootModule(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.startModule(Unknown Source)
    at org.apache.derby.iapi.services.monitor.Monitor.bootServiceModule(Unknown Source)
    at org.apache.derby.impl.db.BasicDatabase.bootStore(Unknown Source)
    at org.apache.derby.impl.db.BasicDatabase.boot(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.boot(Unknown Source)
    at org.apache.derby.impl.services.monitor.TopService.bootModule(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.bootService(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.startProviderService(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.findProviderAndStartService(Unknown Source)
    at org.apache.derby.impl.services.monitor.BaseMonitor.startPersistentService(Unknown Source)
    at org.apache.derby.iapi.services.monitor.Monitor.startPersistentService(Unknown Source)
    ... 48 more
java.lang.NullPointerException
    at DataBaseConnector.insertData(DataBaseConnector.java:43)
    at DatabaseUI$OKAction.actionPerformed(DatabaseUI.java:53)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6504)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6269)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4860)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2713)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
    at java.awt.EventQueue.access$000(EventQueue.java:101)
    at java.awt.EventQueue$3.run(EventQueue.java:666)
    at java.awt.EventQueue$3.run(EventQueue.java:664)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:680)
    at java.awt.EventQueue$4.run(EventQueue.java:678)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
java.lang.NullPointerException
    at DataBaseConnector.closeConnection(DataBaseConnector.java:29)
    at DataBaseConnector.insertData(DataBaseConnector.java:65)
    at DatabaseUI$OKAction.actionPerformed(DatabaseUI.java:53)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6504)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6269)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4860)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2713)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
    at java.awt.EventQueue.access$000(EventQueue.java:101)
    at java.awt.EventQueue$3.run(EventQueue.java:666)
    at java.awt.EventQueue$3.run(EventQueue.java:664)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:680)
    at java.awt.EventQueue$4.run(EventQueue.java:678)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
BUILD SUCCESSFUL (total time: 12 seconds)

为什么是这样？请帮忙！

除了第一个主要问题，我想再问两个问题。

  1. 我必须在这里给出数据库的显式位置作为连接。但是，当我把它交给客户时，我该怎么做呢？
  2. 我必须使用 netbeans 手动启动数据库连接。反正有没有自动启动数据库连接？使用代码？

请帮我。谢谢

4

3 回答 3

7

你的程序包含一些误解和错误的分配！

  • 从您的图像中，您可以看到您的 DATABASE = contactDB 不是联系人。
    "jdbc:derby:C:/Users/yohan/.netbeans-derby/contact" 是错误
    的 "jdbc:derby:C:/Users/yohan/.netbeans-derby/contactDB" 现在只有数据库是正确的。
    错误：另一个 Derby 实例可能已经启动了数据库 C:\Users\yohan.netbeans-derby\contact。

  • 对于 Con.String 最好不要使用 PATH
    将工作"jdbc:derby://localhost:1527/C:/Users/yohan/.netbeans-derby/contactDB","yohan","xyz"
    更好的是" jdbc:derby://localhost:1527/contactDB","yohan","xyz"

最好指定表的完整路径。否则，它只能在 Netbeans 中工作，具有已打开的表和默认模式。

  • prepareStatement
    仅在 Netbeans con.prepareStatement("insert into FRIENDS values(?,?,?)");
    更好的是 con.prepareStatement("insert into APP.FRIENDS values(?,?,?)");

现在看看这个！

    ps.setInt(1, id);
    ps.setString(1, firstName);
    ps.setString(2, lastName);
  • 首先，您使用 setInt() 设置id 。
  • 第二现在您使用字符串setString() 设置id ( firstName !!!!!)
  • 最后，您在 ps 中使用 lastName 和 lastName 覆盖 firstName。是空的。

这会给你下一个错误

发生错误时最好不要继续运行程序。错误列表会变长。很难阅读。在您的情况下，第一个错误在createConnection中并在 !!

  • 错误创建连接
  • 错误 con.prepareStatement("...
  • 错误 ps.executeUpdate()
  • 错误关闭连接（）

用boolean和if测试它！

private boolean createConnection()
{
    try
    {
        Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
        con = DriverManager.getConnection("jdbc:derby://localhost:1527/contactDB","yohan","xyz");
    }
    catch(Exception e)
    {   
        System.out.println("Error getConnection");
        return false;
    }
 return true;   
}

如果连接失败，则无需进一步运行。

public void insertData(int id, String firstName, String lastName)
    {
       if (createConnection()) {
        try
        {
            PreparedStatement ps = con.prepareStatement("INSERT INTO APP.FRIENDS values(?,?,?)");
            ps.setInt(1, id);
            ps.setString(2, firstName);
            ps.setString(3, lastName);
[...]

我希望这对你有所帮助。

于 2012-09-30T05:38:00.697 回答
7

你的datasae已经连接断开右键单击->断开连接现在试试，

它肯定会起作用。

于 2013-06-02T16:53:09.470 回答
0

您的数据库已经连接，您必须断开连接。右键单击->断开连接。现在再试一次，它肯定会奏效。

于 2020-12-10T23:57:08.167 回答