eclipse操作oracle出现异常

java.sql.SQLRecoverableException: Io 异常: The Network Adapter could not establish the connection
    at oracle.jdbc.driver.SQLStateMapping.newSQLException(SQLStateMapping.java:101)
    at oracle.jdbc.driver.DatabaseError.newSQLException(DatabaseError.java:112)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:173)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:229)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:458)
    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:474)
    at java.sql.DriverManager.getConnection(DriverManager.java:582)
    at java.sql.DriverManager.getConnection(DriverManager.java:185)
    at JDBCExample.main(JDBCExample.java:11)处理已完成。