how to debug a jni dll

I have a small java program. It loads a jni dll and that dll loads a normal win32 dll. I would like to debug which arguments the Java application in the end provides to one specific call of the win32 dll. My plan was to put a breakpoint on this DLL call in ollydbg and then inspect the stack. But I have to provide an executable when I start the debug mode in ollydbg so the only option I have is provide java.exe with the parameters to start my java program. But I can only set the breakpoint in the DLL when the DLL is eventually loaded which requires me to basically run the program. I can't see how I can't "halt" the execution to set the breakpoint and if I could halt somehow I wouldn't need the breakpoint. Can anyone tell me what I need to do?

Solution

You can instruct the debugger to break when a particular dll is loaded.

load "java.exe" in Ollydbg
Go to "Options > options" menu (ALT + O).
On the option window, on the left menu, go to "Debugging > Events"
Check "Pause on new module (DLL)"
(Optionally) Check "Only on the following modules" (otherwise the debugger will break for all loaded modules, including system ones).
Click "Add" button and fill the box with the name of your dll.
Click "OK" at the bottom of the "Debugging events" window

Go to "File > Set new arguments" menu if you want to pass some args to java.exe.
Restart the program (CTRL + F2), this is needed to take the changes into account.
Run the program, it should break when you jni dll is loaded (on DLL main).
Press "CTRL + N" to see the names exported by your DLL
- note: you can actually type the name you are searching for on this window
- it looks like that (example with kernel32.dll system DLL, I typed "CreatefileW" on the window):

Press F2 on the function name you want to break on (this put a break point on the function)
Run program with F9: if the function is called, this should break.