Java 控制檯執行帶自定義包定義的類，出現「Exception in thread "main" java.lang.NoClassDefFoundError: ConnectSQLServer (

一、先說明一下代碼實現:自定義package sine，

源代碼保存路徑爲：E:\JSP\HibernateDemo\HibernateDemoProject\src\sine\ConnectSQLServer.java

 1 package sine;
 2 import java.sql.*;
 3 
 4 public class ConnectSQLServer {
 5 
 6     public static void main(String args[]){
 7         String url="jdbc:sqlserver://localhost:1433;DatabaseName=pubs";
 8         
 9         String user_name="sa";
10         String user_password="sine88";
11         String sqlStr="select * from jobs;";
12         
13         try{
14             Connection con=DriverManager.getConnection(url,user_name,user_password);
15             System.out.println("Connect Success!");
16             Statement st=con.createStatement();
17             System.out.println("Create Statement Success!");
18             ResultSet rs=st.executeQuery(sqlStr);
19             System.out.println("Query Success!");
20             System.out.println("-----------------------");
21             
22             while(rs.next()){
23                 System.out.println(rs.getString("job_desc"));
24             }
25             rs.close();
26             st.close();
27             con.close();
28         }
29         catch(Exception err){
30             System.out.println("Connect failed!");
31             err.printStackTrace(System.out);
32         }
33     }
34 }

 

二、切換到java源代碼所在的文件夾目錄下，編譯java代碼。

E:\JSP\HibernateDemo\HibernateDemoProject\src\sine>javac ConnectSQLServer.java

三、字節碼的解釋與運行：java ConnectSQLServer 出現以下錯誤信息：

E:\JSP\HibernateDemo\HibernateDemoProject\src\sine>java ConnectSQLServer
Exception in thread "main" java.lang.NoClassDefFoundError: ConnectSQLServer (wrong name: sine/ConnectSQLServer)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
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 sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)

四、解決方法

先將控制檯上的目錄切換到包名的上一個文件夾處，例如，這裏的package名稱爲sine，那麼這裏就切換到sine的上一層目錄，也就是src目錄下，

而後執行以下命令：E:\JSP\HibernateDemo\HibernateDemoProject\src>java sine.ConnectSQLServer

此時結果以下：

E:\JSP\HibernateDemo\HibernateDemoProject\src>java sine.ConnectSQLServer
Connect Success!
Create Statement Success!
Query Success!
-----------------------
New Hire - Job not specified
Chief Executive Officer
Business Operations Manager
Chief Financial Officier
Publisher
Managing Editor
Marketing Manager
Public Relations Manager
Acquisitions Manager
Productions Manager
Operations Manager
Editor
Sales Representative
Designer

 

屆時，問題解決！ 同理，加入包名是：org.sine，那麼執行的時候就須要切換到org的上一個目錄下了。