Oracle SQL Developer无法创建连接：IO错误及账号、安装相关求助

Hey there, let's break down your Oracle SQL Developer issues step by step to get you connected smoothly!

This error usually points to a problem with network connectivity or database setup. Here are the most likely fixes:

• Check if the Oracle Database Service is running

  • On Windows: Open the Services app (press Win + R, type services.msc), look for a service named OracleServiceORCL (ORCL is the default SID; yours might be different). If it's stopped, right-click and start it.
  • On Linux: Run lsnrctl status in the terminal to check the listener status. If it's not running, use lsnrctl start to launch it. You can also check the database service with systemctl start oracle (depending on your setup).

• Verify your connection details
  Double-check these fields in the New Connection window:

  • Hostname/IP: For a local database, use localhost or 127.0.0.1. For remote, use the database server's actual IP or hostname.
  • Port: Default is 1521—make sure you didn't mistype this.
  • SID/Service Name: Default SID is ORCL; service name might be something like ORCL.localdomain (you can find this via lsnrctl status under "Services Summary").

• Check firewall settings
  Ensure your local firewall (Windows Defender Firewall, iptables, etc.) isn't blocking port 1521. Temporarily disable the firewall to test, or add an inbound/outbound rule allowing traffic on port 1521.

• Update your JDBC driver (if needed)
  SQL Developer comes with a built-in JDBC driver, but if you're connecting to a very new or old Oracle version, it might be incompatible. To update:

  1. Go to Tools > Preferences > Database > Third Party JDBC Drivers.
  2. Click Add Entry and select the latest ojdbc.jar file matching your Oracle version.

• Validate listener configuration
  Check the listener.ora file (located in $ORACLE_HOME/network/admin on Linux, %ORACLE_HOME%\network\admin on Windows) to ensure it's configured to listen on the correct port and hostname. A basic valid configuration might look like this:

  LISTENER =
    (DESCRIPTION_LIST =
      (DESCRIPTION =
        (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
      )
    )
  

Oracle comes with several built-in users by default, depending on your installation type:

• SYS: The superuser with full administrative privileges. When logging in, you need to select either the SYSDBA or SYSOPER role from the dropdown.
• SYSTEM: A management user with almost all privileges (second only to SYS). No special role is needed for login.
• SCOTT: A classic sample user (often locked by default). To unlock it, connect as SYS/SYSTEM and run these commands:

  ALTER USER SCOTT ACCOUNT UNLOCK;
  ALTER USER SCOTT IDENTIFIED BY tiger;
  

  The default password for SCOTT is tiger.

If you created your own user during setup, use the username and password you set. Also, make sure the user has the CREATE SESSION privilege to connect (grant it with GRANT CREATE SESSION TO your_username; if needed).

In most cases, no extra components are required—Oracle SQL Developer is a standalone Java application that includes all basic tools and drivers to connect to Oracle databases.

That said, there are a few edge cases where you might need additional setup:

• If you're connecting to a very new Oracle version (e.g., Oracle 23c), the built-in JDBC driver might not support it. You'll need to download the matching ojdbc.jar and add it to SQL Developer's driver list (as explained earlier).
• For extremely old Oracle versions (e.g., Oracle 9i), you'll need to find and install an older compatible JDBC driver.
• If you prefer using Oracle Instant Client, you can configure SQL Developer to use its drivers, but this is optional— the built-in drivers work perfectly for most scenarios.

内容的提问来源于stack exchange，提问作者Nilima Kumari