代码没有错，是系统的问题吗？

Question

Exception in thread "main" java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at Date.TestDate.main(TestDate.java:10)

package Date;
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.SimpleDateFormat;
public class TestDate {
    public static void main(String []args)throws Exception {
        Class.forName("com.mysql.jdbc.Driver").newInstance();
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/mydata?user=root&password=root");
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery("select pdate from article");
        while(rs.next()) {
            Date d = rs.getDate("pdate");
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日");
            System.out.println(sdf.format(d));
        }
        rs.close();
        stmt.close();
        conn.close();
    }
}

Answer 1

mysql的driver没有在java程序的classpath里面