在 Windows Java 中检查 USB 驱动器的文件系统完整性

Question

Our application involves an external device that mounts as a USB mass storage device. I need to be able to check the integrity of that USB mass storage device from a Java application, running on Windows.

Currently I execute "chkdsk", which works fine unless the user's computer isn't configured for English. (Because I need to examine the chkdsk output to determine the state of the drive.) And, surprise, surprise, not every computer in the world is configured for English!

There is a Win32 class called "Win32_Volume" with a method called "Chkdsk" that is just what I'm looking for.

I need to call it from Java, and JNA seems the way to go.

How can I use COM to call a method from a Win32 WMI class?

Answer 1

You can send an FSCTL_IS_VOLUME_DIRTY message using DeviceIoControl .

Here is and example of calling DeviceIoControl.

Or you can use WMI, both the the Win32_Volume and the Win32_LogicalDisk class expose a DirtyBitSet property. However WMI is really inteded for scripting languages and is not preferred because of it's incredible performance overhead.

Answer 2

The Win32_Volume documentation with the Chkdsk method you cite indicates it is a legacy API, but has not yet been deprecated so you could use it.

The current Storage Management API equivalent is MSFT_Volume . It has a Diagnose method that looks to perform similar functionality.

To execute a method on a WMI object via COM you need to obtain a pointer to a WbemServices object. It has an ExecMethod method you can invoke that does what you want for WMI classes. The code to retrieve this object is in JNA's WbemcliUtil class as a return type from the connectServer() method.

You will also need the full path to the Class Object; this is available by querying WMI for the __PATH , similarly to how you'd query any other field. That same WbemcliUtil class has a WmiQuery class you can instantiate to execute the query, collecting that path from the WmiResult . See the JNA test classes for examples on using these.

Finally, you can execute the WMI method. The code below will accomplish it for String properties, eg, the MSFT_StorageDiagnoseResult object you'd get from MSFT_Volume 's Diagnose method. You'd have to treat other return types differently.

/**
 * Convenience method for executing WMI methods without any input parameters
 * 
 * @param svc
 *            The WbemServices object
 * @param clsObj
 *            The full path to the class object to execute (result of WMI
 *            "__PATH" query)
 * @param method
 *            The name of the method to execute
 * @param properties
 *            One or more properties returned as a result of the query
 * @return An array of the properties returned from the method
 */
private static String[] execMethod(WbemServices svc, String clsObj, String method, String... properties) {
    List<String> result = new ArrayList<>();
    PointerByReference ppOutParams = new PointerByReference();
    HRESULT hres = svc.ExecMethod(new BSTR(clsObj), new BSTR(method), new NativeLong(0L), null, null, ppOutParams,
            null);
    if (COMUtils.FAILED(hres)) {
        return new String[0];
    }
    WbemClassObject obj = new WbemClassObject(ppOutParams.getValue());
    VARIANT.ByReference vtProp = new VARIANT.ByReference();
    for (String prop : properties) {
        hres = obj.Get(new BSTR(prop), new NativeLong(0L), vtProp, null, null);
        if (!COMUtils.FAILED(hres)) {
            result.add(vtProp.getValue() == null ? "" : vtProp.stringValue());
        }
    }
    obj.Release();
    return result.toArray(new String[result.size()]);
}

A more complete example of querying a COM object, where I extracted the above code, is in this utility class which queries the GetOwner() and GetOwnerSid() methods on the Win32_Process object. It's legacy code from before I contributed the WbemCli class to JNA, so you'll have to adapt some of it, but it should be a good starting point.