您并不是必须使用回调来设置用户名或密码。

You don't have to use a callback for either the username or the password.

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参见 清单 2 中以这种方式设置用户名和密码属性的示例。

See the Listing 2 example of setting the username and password properties in the context.

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如果此用户名和密码是为给定的调用设置的，则线程本地用户名和密码将覆盖它们。

This username and password is overridden by the thread local username and password if they are set for a given invocation.

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