我写了两个简单的类。如下:
//////////////////////////////////
package www.liwenjie.com;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;public class DataBaseUser { private Statement statement; public DataBaseUser() throws ClassNotFoundException, SQLException {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Driver loaded"); Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/zhouyan?user=root&password=root&useUnicode=true&characterEncoding=GB2312");
System.out.println("Database connected"); statement = connection.createStatement();
}
}//////////////////////////////////////////////////////////
package www.liwenjie.com;import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.SQLException;import javax.swing.JButton;
import javax.swing.JFrame;public class Test extends JFrame { /**
* Launch the application
* @param args
*/
DataBaseUser dbuser;
public static void main(String args[]) {
try {
Test frame = new Test();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
} /**
* Create the frame
*/
public Test() {
super();
setBounds(100, 100, 500, 375);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); final JButton button = new JButton();
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
try {
dbuser = new DataBaseUser();
} catch (ClassNotFoundException e) {
// TODO 自动生成 catch 块
e.printStackTrace();
} catch (SQLException e) {
// TODO 自动生成 catch 块
e.printStackTrace();
}
}
});
button.setText("New JButton");
getContentPane().add(button, BorderLayout.CENTER);
//
}}
/////////////////////////////////点击确定按钮报如下错误
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at www.liwenjie.com.DataBaseUser.<init>(DataBaseUser.java:13) at www.liwenjie.com.Test$1.actionPerformed(Test.java:40) at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)以上是在myeclipse中运行的。
如果我把这两个文件的包头去掉,使用别的编译软件编译并运行就没有任何错误。
//////////////////////////////////
package www.liwenjie.com;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;public class DataBaseUser { private Statement statement; public DataBaseUser() throws ClassNotFoundException, SQLException {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Driver loaded"); Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/zhouyan?user=root&password=root&useUnicode=true&characterEncoding=GB2312");
System.out.println("Database connected"); statement = connection.createStatement();
}
}//////////////////////////////////////////////////////////
package www.liwenjie.com;import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.SQLException;import javax.swing.JButton;
import javax.swing.JFrame;public class Test extends JFrame { /**
* Launch the application
* @param args
*/
DataBaseUser dbuser;
public static void main(String args[]) {
try {
Test frame = new Test();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
} /**
* Create the frame
*/
public Test() {
super();
setBounds(100, 100, 500, 375);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); final JButton button = new JButton();
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
try {
dbuser = new DataBaseUser();
} catch (ClassNotFoundException e) {
// TODO 自动生成 catch 块
e.printStackTrace();
} catch (SQLException e) {
// TODO 自动生成 catch 块
e.printStackTrace();
}
}
});
button.setText("New JButton");
getContentPane().add(button, BorderLayout.CENTER);
//
}}
/////////////////////////////////点击确定按钮报如下错误
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at www.liwenjie.com.DataBaseUser.<init>(DataBaseUser.java:13) at www.liwenjie.com.Test$1.actionPerformed(Test.java:40) at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)以上是在myeclipse中运行的。
如果我把这两个文件的包头去掉,使用别的编译软件编译并运行就没有任何错误。
解决方案 »
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驱动问题,看看驱动是否加载
然后找到你的mysql驱动jar包,选中它,保存
如果没有可以在下面的网址下载:
http://dev.mysql.com/downloads/connector/j/5.1.html
或者
http://dev.mysql.com/downloads/connector/j/5.0.html