com.mysql.jdbc.Driver嘗試創建數據庫時拋出ClassNotFoundException

Question

好吧，我變得非常煩躁，因爲我意識到這很容易，但在這一點上，我不知道還有什麼要嘗試。該計劃簡單地應該創建一個存儲硬幣的名稱，數量和價值的硬幣表。我已經開始從命令行啓動程序，但沒有完成這項工作後，我將其更改爲在NetBeans中執行。我不斷收到相同的錯誤信息。我搜索瞭解決方案，並且找不到問題，因爲我的驅動程序類似乎是需要的。我目前使用的驅動程序爲com.mysql.jdbc.Driver。

public class CoinDataBase { 

    static String file = "C:\\Users\\Dan\\Desktop\\database.properties.txt"; 

    public static void main(String[] args) throws SQLException, IOException, 
     ClassNotFoundException { 


    SimpleDataSource.init(file); 

    Connection conn = SimpleDataSource.getConnection(); 
    try 
    { 
     Statement stat = conn.createStatement(); 

     stat.execute("CREATE TABLE Coin (Name VARCHAR(12),Value " 
       + "DECIMAL(5,2),QTY DECIMAL(5,0),Value DECIMAL(5,2)" 
       + ",Total DECIMAL(5,2))"); 
     stat.execute("INSERT INTO Coin VALUES('Penny',.01,5,.05)"); 
     stat.execute("INSERT INTO Coin VALUES('Nickel',.05,2,.10)"); 
     stat.execute("INSERT INTO Coin VALUES('Dime',.10,3,.30)"); 
     stat.execute("INSERT INTO Coin VALUES('Quarter',.25,2,.50)"); 
     stat.execute("INSERT INTO Coin VALUES('Half Dollar',.50,3,1.50)"); 
     stat.execute("INSERT INTO Coin VALUES('Dollar',1.00,2,2.00)"); 

     ResultSet result = stat.executeQuery("SELECT * FROM Coin"); 
     result.next(); 
     System.out.println(result.getString("Name")); 
    } 
    finally 
    { 
     conn.close(); 
    } 
    } 
    } 

我的第二類...

class SimpleDataSource { 

    private static String url, username, password; 

    static void init(String fileName) throws IOException, ClassNotFoundException 
    { 
     Properties props = new Properties(); 
     FileInputStream in = new FileInputStream(fileName); 
     props.load(in); 

     String driver = props.getProperty("jdbc.driver"); 
     url = props.getProperty("jdbc.url"); 
     username = props.getProperty("jdbc.username"); 
     if (username == null) username = ""; 
     password = props.getProperty("jdbc,password"); 
     if (password == null) password = ""; 
     if (driver != null) 
     Class.forName(driver); 
    } 

    static Connection getConnection() throws SQLException{ 
    return DriverManager.getConnection(url, username, password); 
    } 
    } 

和錯誤消息在全：

Exception in thread "main" java.lang.ClassNotFoundException: com.mysql.jdbc.Driver 
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366) 
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354) 
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423) 
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) 
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356) 
    at java.lang.Class.forName0(Native Method) 
    at java.lang.Class.forName(Class.java:186) 
    at coindatabase.SimpleDataSource.init(SimpleDataSource.java:28) 
    at coindatabase.CoinDataBase.main(CoinDataBase.java:20) 
Java Result: 1 

我真的很感激任何幫助。我不知道我哪裏錯了。我可以通過瀏覽NetBeans中的服務來連接和創建數據庫，所以我認爲它不配置錯誤。

Answer 1

1）確保oracle.jar是在項目的運行類路徑：

http://netbeans.org/kb/docs/java/project-setup.html

2）這是值得嘗試oracle.jdbc.Driver.OracleDriver

「希望幫助

Answer 2

什麼工作我嘗試在Ubuntu上使用Eclipse連接到Postgresql DB（javaSE 1.6）時發生同樣的錯誤。我去了Eclipse - > Project - > Proprieties - > Java Build Path - > Libraries - >添加外部jar並添加了postgresql-9.3-1100.jdbc4.jar從http://jdbc.postgresql.org/download.html。

Connection con = null; 
    Statement st = null; 
    ResultSet rs = null; 


    String url = "jdbc:postgresql://localhost:5432/unnamed_db"; 
    String user = "postgres"; 
    String password = "*"; 

    try { 
     con = DriverManager.getConnection(url, user, password); 
     st = con.createStatement(); 
     rs = st.executeQuery("select * from table;"); 

     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); 
     } 
    }