java异常

这是我用java在eclipse中编写的连接orcal 10g数据库的程序:
package com.tools;import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;public class DataCommuniction { static Connection conn = null; 
    static ResultSet rs = null; 
static Statement stmt = null; 
static String name = "sys";
static String password = "aa";
static String url = "jdbc:oracle:thin:@127.0.0.1:1521:system";
static String sql = "select * from myTable";

    public static void main(String[] args)
{

try {
Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection(url,name,password);
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
while(rs.next())
{
System.out.println(rs.getString(1));
}
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}


}
下面是运行是抛的异常：
java.sql.SQLException: Io 异常: The Network Adapter could not establish the connection
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:125)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:162)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:274)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:328)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:348)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:151)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:563)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at com.tools.DataCommuniction.main(DataCommuniction.java:24)