異常：網絡適配器無法在簡單的jdbc程序中建立連接

Question

我試圖運行一個簡單的jdbc代碼[使用jdk 1.6，oracle 10g]，

package javaapplication2;
import java.text.*;
import java.sql.*;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.io.BufferedWriter;
/**
 * @author animark
 */
public class CallableStatementEx1 {
    public CallableStatementEx1(){;}

public static void main(String s[]) throws Exception {
    try
    {
        Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
        Connection con=null;
        String url= "jdbc:oracle:thin:@//localhost:1521:orcl" ;   
        con = DriverManager.getConnection(url,"scott","password");

        String query="update emp set HIREDATE=?,ENAME=? where empno=?";

        //Step1: Get PreparedStatement
        PreparedStatement ps=con.prepareStatement(query);

        //Prepare java.sql.Date object
        /*
        This logic shows how to convert simple String that is in 
        dd-MM-yyyy format into Date object
        */
        SimpleDateFormat sdf=new SimpleDateFormat("dd-MM-yyyy");
        java.util.Date d=sdf.parse("26-12-2001");
        java.sql.Date newdate=new java.sql.Date(d.getTime());

        //Step2: set parameters
        ps.setDate(1,newdate);
        ps.setString(2,"animark");
        ps.setInt(3,7839);

        //Step3: execute the query
        int i=ps.executeUpdate();

        System.out.println("record updated count: "+i);
        con.close();
    }
    catch(Exception e)
    {
                    e.printStackTrace();

    }
    }//main
}//class

代碼正在編譯正確。 但是當我試圖運行它時，我得到以下異常..

java.sql.SQLException: Io exception: The Network Adapter could not establish the connection
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:146)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:255)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:387)
    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:414)
    at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:165)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:35)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:801)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at javaapplication2.CallableStatementEx1.main(CallableStatementEx1.java:19)

我檢查了oracle服務，所有這些服務都啟動並運行。

另外，請查找其他文件的內容為

================================================== =============================== tnsnames.ora：

# tnsnames.ora Network Configuration File: C:\oraclexe\app\oracle\product\10.2.0\server\BIN\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

================================================== ==================================

sqlnet.ora


# sqlnet.ora Network Configuration File: C:\oraclexe\app\oracle\product\10.2.0\server\BIN\network\admin\sqlnet.ora
# Generated by Oracle configuration tools.

# This file is actually generated by netca. But if customers choose to 
# install "Software Only", this file wont exist and without the native 
# authentication, they will not be able to connect to the database on NT.

SQLNET.AUTHENTICATION_SERVICES= (NTS)

NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)
================================================================================

# listener.ora Network Configuration File: C:\oraclexe\app\oracle\product\10.2.0\server\BIN\network\admin\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = C:\oraclexe\app\oracle\product\10.2.0\server\BIN)
      (PROGRAM = extproc)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    )
  )

================================================== =============================

我能夠使用憑證“scott / password”連接到實例“orcl”，但是當我嘗試連接使用語句時

SQL> connect sys / password @ orcl as sysdba

我收到以下錯誤.. ORA-12514：TNS：監聽器當前不知道連接中請求的服務

描述。

我也為orcl運行LSNRCTL並找到了

適用於32位Windows的LSNRCTL：版本10.2.0.1.0 - 生產於2012年7月22日13:42:30

版權所有（c）1991,2005，Oracle。 版權所有。

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=orcl)))
Services Summary...
Service "PLSExtProc" has 1 instance(s).
  Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service...
    Handler(s):
      "DEDICATED" established:0 refused:0
         LOCAL SERVER
The command completed successfully

如果我在這里做錯了什么，請幫助我。

Answer 1

嘗試從連接URL中取出// 。 代替

    String url= "jdbc:oracle:thin:@//localhost:1521:orcl" ;   

嘗試

    String url= "jdbc:oracle:thin:@localhost:1521:orcl" ;