Java Oracle本地主机连接错误（ORA-12505）

Question

我正在尝试当前连接到当前计算机上的数据库。

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class Main {
    public static void main(String[] argv) throws Exception {

        Connection connection = null;
        try {
            // Load the JDBC driver
            String driverName = "oracle.jdbc.driver.OracleDriver";
            Class.forName(driverName);

            // Create a connection to the database
            String serverName = "localhost";
            String portNumber = "1521";
            String sid = "xe";
            String url = "jdbc:oracle:thin:@" + serverName + ":" + portNumber + ":" + sid;
            String username = "scott";
            String password = "tiger";
            connection = DriverManager.getConnection(url, username, password);
            System.out.println("Success");
        } catch (ClassNotFoundException e) {
            System.out.println("Class Not Found Error");
        } 
    }
}

我不断收到此错误，但我不知道为什么…

Exception in thread "main" java.sql.SQLException: Listener refused the connection with the following error:
ORA-12505, TNS:listener does not currently know of SID given in connect descriptor
The Connection descriptor used by the client was:
localhost:1521:xe

at oracle.jdbc.driver.SQLStateMapping.newSQLException(SQLStateMapping.java:70)
at oracle.jdbc.driver.DatabaseError.newSQLException(DatabaseError.java:110)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:171)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:496)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:411)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:490)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:202)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:33)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:465)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at Main.main(Main.java:21)

在我的服务器中，我使用了命令（以sys登录）SQL>从v $ thread选择实例；（它返回）实例-> xe

我可能做错了什么？

谢谢！

PS我也尝试了127.0.0.1而不是localhost

Answer 1

检查<ORACLE_HOME>\admin\NETWORK目录下的listener.ora文件是否具有以下值：

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