项目场景：

今天在springboot里连接oracle数据库

问题描述：`

报java.sql.SQLRecoverableException: IO 错误: The Network Adapter could not establish the connection

java.sql.SQLRecoverableException: IO 错误: The Network Adapter could not establish the connection
	at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:458)
	at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:546)
	at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:236)
	at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
	at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:521)
	at java.sql.DriverManager.getConnection(DriverManager.java:664)
	at java.sql.DriverManager.getConnection(DriverManager.java:247)
	at com.iss.cms.ifpf.common.enums.IfpfBankCodeCodeEnum.main(IfpfBankCodeCodeEnum.java:123)
Caused by: oracle.net.ns.NetException: The Network Adapter could not establish the connection
	at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:392)
	at oracle.net.resolver.AddrResolution.resolveAndExecute(AddrResolution.java:434)
	at oracle.net.ns.NSProtocol.establishConnection(NSProtocol.java:687)
	at oracle.net.ns.NSProtocol.connect(NSProtocol.java:247)
	at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1102)
	at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:320)
	... 7 more
Caused by: java.net.ConnectException: Connection refused: connect
	at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method)
	at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85)
	at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
	at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
	at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
	at java.net.Socket.connect(Socket.java:589)
	at oracle.net.nt.TcpNTAdapter.connect(TcpNTAdapter.java:150)
	at oracle.net.nt.ConnOption.connect(ConnOption.java:133)
	at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:370)
	... 12 more

原因分析：

我试图通过SQL Developer连接，它工作正常。

解决方案：

最后，我解决了这个问题，这个错误是由使用IPv6协议的JVM引起的，而这个协议是网络/ oracle服务器不支持的。
由于我为我的应用程序使用Tomcat服务器，因此向tomcat添加了以下参数
-Djava.net.preferIPv4Stack=true
或者你可以将这个参数作为系统环境变量添加为：
有效名称： _JAVA_OPTIONS
变量值： -Djava.net.preferIPv4Stack=true

源文件https://www.656463.com/wenda/JavaIoycwlspqwfjllj_201