JT400默认使用QUSER，调用RPG程序时如何切换为当前用户？

Great questions—let’s tackle them one by one to get your JT400 and RPG setup working as expected:

Absolutely. QUSER is only used as the default when you don’t provide explicit authentication credentials during your IBM i connection setup. Here are the most common ways to switch to a different user:

• Explicit credentials in code: When instantiating the AS400 object, pass your target username and password directly:

  AS400 as400 = new AS400("your-ibm-i-system", "target-username", "target-password");
  

• JDBC connection configuration: If you’re using JT400 for JDBC connections, include the user and password in your JDBC URL or connection properties:

  jdbc:as400://your-ibm-i-system;user=target-username;password=target-password
  

• System properties: Set global JT400 properties before initializing your connection (useful if you want to apply this across your app):

  System.setProperty("com.ibm.as400.access.User", "target-username");
  System.setProperty("com.ibm.as400.access.Password", "target-password");
  

The root cause here is that your Java app is still connecting to IBM i using QUSER’s identity—so the RPG program runs in a job owned by QUSER, which is why the PSDS picks up that user ID. To fix this:

1. Use the correct connection credentials: First, update your JT400 connection to use the actual current user’s credentials (follow the steps from the first question). This ensures the IBM i job associated with your connection runs under that user, not QUSER.
2. Verify your RPG PSDS setup: Make sure your PSDS is correctly referencing the user ID field. The standard PSDS has the job’s user ID starting at position 129, with a length of 10 characters. Example RPGLE code:

   Dcl-Ds Psds Qualified;
       JobUserId Char(10) Pos(129);
   End-Ds;
   

3. Integrated authentication (if applicable): If you’re on a Windows machine and want to use the logged-in OS user’s credentials for IBM i access, enable default user authentication:

   AS400 as400 = new AS400("your-ibm-i-system");
   as400.setUseDefaultUser(true);
   

   This will pass your Windows user’s credentials to IBM i, and the RPG job will run under that user—so the PSDS will return the correct ID.

A quick best practice: Avoid using QUSER for application connections unless strictly necessary. QUSER has broad privileges, so using a least-privilege user for your app connections is better for security.

内容的提问来源于stack exchange，提问作者Bashdi