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我正在尝试使用以下代码（隐藏主机、服务、用户和密码）使用 Oracle JDBC 驱动程序通过 Java 连接到 Oracle 数据库：

import java.sql.*;

public class Main {
    public Main () {
        try {
            String host = "HOST_NAME";
            String port = "1521";
            String service = "SERVICE_NAME";
            String user = "SCHEMA_USER";
            String password = "SCHEMA_PASSWORD";

            Class.forName("oracle.jdbc.driver.OracleDriver");

            Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=" + 
                        host + 
                        ")(PORT=" + 
                        port + 
                        ")))(CONNECT_DATA=(SERVICE_NAME=" + 
                        service + 
                        ")))", 
                        user, 
                        password);

            connection.close ();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main (String args) {
        new Main ();
    }
}

但是，我收到以下错误：

java.sql.SQLException: IO Error: 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(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at com.acxiom.axle.reporting.database.DatabaseConnection.connect(DatabaseConnection.java:23)
    at com.acxiom.axle.reporting.Reporting.establishDatabaseConnection(Reporting.java:53)
    at com.acxiom.axle.reporting.Reporting.beginReporting(Reporting.java:20)
    at com.acxiom.axle.reporting.Entry.<init>(Entry.java:28)
    at com.acxiom.axle.reporting.Entry.main(Entry.java:118)
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)
    ... 11 more
Caused by: java.net.UnknownHostException: null
    at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
    at java.net.InetAddress$2.lookupAllHostAddr(Unknown Source)
    at java.net.InetAddress.getAddressesFromNameService(Unknown Source)
    at java.net.InetAddress.getAllByName0(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at java.net.InetAddress.getAllByName(Unknown Source)
    at oracle.net.nt.TcpNTAdapter.connect(TcpNTAdapter.java:117)
    at oracle.net.nt.ConnOption.connect(ConnOption.java:133)
    at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:370)
    ... 16 more

奇怪的是，我可以从 PL/SQL Developer 连接到数据库，可以 ping 远程主机，还可以通过 1521 端口 telnet 到远程主机。

为什么似乎只有 Java 会给出 UnknownHostException，但我可以将主机与其他应用程序连接并 ping 通？

编辑：我从上面的连接字符串中删除了“hr/hr”。我已按原样尝试连接，但仍会收到相同的错误。我还尝试更改连接字符串以匹配他的答案中列出的版本 morgano，结果相同。最后，我尝试将端口号更改为我知道它没有在侦听的端口，但它仍然收到相同的错误。

4

2 回答 2

1

连接字符串的格式正确。问题是没有设置主机。它是null，或者也许是字符串"null"。根本没有其他方法可以生成错误消息java.net.UnknownHostException: null

在您的示例代码中，您编写String host = "HOST_NAME";. 这使它看起来像在您的真实代码中您正在为变量分配一个常量字符串host。但是，我会伸出脖子说，在你的真实代码中你没有这样做。您正在从某个地方查找主机名，此查找由于某种原因而失败，您没有检查这一点，因此您将一个空值传递给连接字符串。

于 2020-02-15T20:02:07.920 回答
0

您的 JDBC url 错误，根据文档，它应该类似于：

jdbc:oracle:driver_type:[用户名/密码]@//host_name:port_number/service_name

在您的情况下，您的代码将类似于：

import java.sql.*;

public class Main {

    public Main () {
        try {
            String host = "HOST_NAME";
            String port = "1521";
            String service = "SERVICE_NAME";
            String user = "SCHEMA_USER";
            String password = "SCHEMA_PASSWORD";

            Class.forName("oracle.jdbc.driver.OracleDriver");

            Connection connection = DriverManager.getConnection(
                "jdbc:oracle:thin:@//" + host
                + ":" + port + "/" + service, user, password);

            connection.close ();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main (String args) {
        new Main ();
    }
}
于 2015-03-24T19:28:26.483 回答