我工作在Windows 8類未發現異常一切似乎是正確
下面使用MySQL連接口J Java和MySQL之間的簡單連接即使是我試圖執行代碼:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
public class Version {
public static void main(String[] args) {
Connection con = null;
Statement st = null;
ResultSet rs = null;
String url = "jdbc:mysql://localhost:3306/test";
String user = "testuser";
String password = "test623";
try {
con = DriverManager.getConnection(url, user, password);
st = con.createStatement();
rs = st.executeQuery("SELECT VERSION()");
if (rs.next()) {
System.out.println(rs.getString(1));
}
} catch (SQLException ex) {
Logger lgr = Logger.getLogger(Version.class.getName());
lgr.log(Level.SEVERE, ex.getMessage(), ex);
} finally {
try {
if (rs != null) {
rs.close();
}
if (st != null) {
st.close();
}
if (con != null) {
con.close();
}
} catch (SQLException ex) {
Logger lgr = Logger.getLogger(Version.class.getName());
lgr.log(Level.WARNING, ex.getMessage(), ex);
}
}
}
}
編譯: javac的Version.java(不用誤差併產生類文件)
執行: java命令 「路徑到MySQL連接器的java jar文件」 版本
執行結果:
Exception in thread "main" java.lang.NoClassDefFoundError: Version
Caused by: java.lang.ClassNotFoundException: Version
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)
Could not find the main class: Version. Program will exit.
任何想法,我錯了?
如果你'jar xf'新編譯的jarfile會發生什麼?什麼文件留在新建的目錄中? – Rogue