Eclipse中JDBC连接Oracle数据库抛出异常

public class Jdbc1 {

    public static void main(String[] args) throws ClassNotFoundException, SQLException {
            Class.forName("oracle.jdbc.OracleDriver");
            //System.out.println("OK");
            String url = "jdbc:oracle:thin:@192.168.1.102:1521:orcl";
            String username = "system";
            String password = "orcl";
            Connection conn = DriverManager.getConnection(url, username, password);
            System.out.println(conn.getClass());
    }

}

Exception in thread "main" java.sql.SQLException: Io 异常: 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:439)
    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(DriverManager.java:664)
    at java.sql.DriverManager.getConnection(DriverManager.java:247)
    at cn.csq.jdbc.Jdbc1.main(Jdbc1.java:15)
一直提示这个异常，网上找了好多方法都不行啊啊，有大神知道哪里错了吗？我在sqlplus能连接数据库，在PLSQL Developer也能进去