Io 错误: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=169870080)(ERR=12505

Io 异常: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=169870080)(ERR=12505
异常如下，我是在junit中测试的，查了网上的基本都说是sid出错，但是查了貌似也没有出错啊！求解答，谢谢

true

java.sql.SQLException: Io 异常: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=169870080)(ERR=12505)(ERROR_STACK=(ERROR=(CODE=12505)(EMFI=4))))

	at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)

	at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)

	at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:333)

	at oracle.jdbc.driver.OracleConnection.<init>(OracleConnection.java:404)

	at oracle.jdbc.driver.OracleDriver.getConnectionInstance(OracleDriver.java:468)

	at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:314)

	at java.sql.DriverManager.getConnection(DriverManager.java:664)

	at java.sql.DriverManager.getConnection(DriverManager.java:247)

	at myServlet.CheckServletTest.test(CheckServletTest.java:27)

	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

	at java.lang.reflect.Method.invoke(Method.java:483)

	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)

	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)

	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)

	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)

	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)

	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)

	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)

	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)

	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)

	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)

	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)

	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)

	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)

	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)

	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)

	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)

	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

下面是我源代码：

package myServlet;

import static org.junit.Assert.*;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import org.junit.Test;

public class CheckServletTest {

	@Test

	public void test() {

		final String DRIVER = "oracle.jdbc.driver.OracleDriver";

		final String URL = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";

		final String USER = "scott";

		final String PASS = "simon";

		Connection connection = null;

		PreparedStatement statement = null;

		ResultSet set = null;

		System.out.println(true);

		try {

			Class.forName(DRIVER);

			connection = DriverManager.getConnection(URL, USER, PASS);

		System.out.println("@@@@@@@@@@@@@@");

//			statement = connection

//					.prepareStatement("select * from ajaxmember where mid=?");

//			statement.setString(1, "simon");

//			set = statement.executeQuery();

//			while (set.next()) {

//				System.out.println(set.getString(1));

//

//			}

		} catch (Exception e) {

			e.printStackTrace();

			// TODO: handle exception

		} finally {

			try {

				set.close();

				statement.close();

				connection.close();

			} catch (Exception e2) {

				// TODO: handle exception

			}

		}		

	}

}

------解决思路----------------------
先单步调试一下，后用SQLPLUS连接试试，确认连接串是否正确