FOP for Android?

问题

I recently compiled an Android app using FOP as I want to convert some XML into a PDF file. However I don't think the FOP JAR files are mean't to work on Android. Are there any versions of FOP available for Android? Or any other XML to PDF converter I could use within my app instead of connecting to a FOP enabled server on the Internet?

I've tried including fop.jar and the xmlgraphics.jar but even with those added to my project, the call to FopFactory.newInstance() fails.

Here's my code snippet for the button click that calls FOP:

// Add button listener
btnCreatePDF.setOnClickListener(new OnClickListener()
        {
            @Override
            public void onClick(View v)
            {   
                FopFactory fopFactory = FopFactory.newInstance();
                OutputStream out = new BufferedOutputStream(new FileOutputStream(new File("/sdcard/test.pdf")));
                Fop fop = fopFactory.newFop(MimeConstants.MIME_PDF, out);
                TransformerFactory factory = TransformerFactory.newInstance();
                Transformer transformer = factory.newTransformer();
                Source src = new StreamSource(new File("/sdcard/test.fo"));
                Result res = new SAXResult(fop.getDefaultHandler());

                transformer.transform(src, res);

                out.close();
            }
        });

The compiler is also giving a me a bunch of Dxwarning: Ignoring InnerClasses attribute... errors. Here's the error when I click the button to create the PDF:

02-22 14:16:23.641: WARN/System.err(5590): java.lang.UnsupportedOperationException: Don't know how to handle "application/pdf" as an output format. Neither an FOEventHandler, nor a Renderer could be found for this output format.
02-22 14:16:23.641: WARN/System.err(5590):     at org.apache.fop.render.RendererFactory.createFOEventHandler(RendererFactory.java:361)
02-22 14:16:23.641: WARN/System.err(5590):     at org.apache.fop.fo.FOTreeBuilder.(FOTreeBuilder.java:105)
02-22 14:16:23.641: WARN/System.err(5590):     at org.apache.fop.apps.Fop.createDefaultHandler(Fop.java:101)
02-22 14:16:23.641: WARN/System.err(5590):     at org.apache.fop.apps.Fop.(Fop.java:79)
02-22 14:16:23.641: WARN/System.err(5590):     at org.apache.fop.apps.FopFactory.newFop(FopFactory.java:271)
02-22 14:16:23.641: WARN/System.err(5590):     at org.apache.fop.apps.FopFactory.newFop(FopFactory.java:248)
02-22 14:16:23.641: WARN/System.err(5590):     at com.zebdor.signal88.ProposalCalculator$3.onClick(ProposalCalculator.java:158)
02-22 14:16:23.641: WARN/System.err(5590):     at android.view.View.performClick(View.java:2501)
02-22 14:16:23.641: WARN/System.err(5590):     at android.view.View$PerformClick.run(View.java:9107)
02-22 14:16:23.641: WARN/System.err(5590):     at android.os.Handler.handleCallback(Handler.java:587)
02-22 14:16:23.641: WARN/System.err(5590):     at android.os.Handler.dispatchMessage(Handler.java:92)
02-22 14:16:23.641: WARN/System.err(5590):     at android.os.Looper.loop(Looper.java:123)
02-22 14:16:23.641: WARN/System.err(5590):     at android.app.ActivityThread.main(ActivityThread.java:3812)
02-22 14:16:23.641: WARN/System.err(5590):     at java.lang.reflect.Method.invokeNative(Native Method)
02-22 14:16:23.641: WARN/System.err(5590):     at java.lang.reflect.Method.invoke(Method.java:507)
02-22 14:16:23.641: WARN/System.err(5590):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
02-22 14:16:23.641: WARN/System.err(5590):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
02-22 14:16:23.641: WARN/System.err(5590):     at dalvik.system.NativeStart.main(Native Method)

回答1:

With Android, you can't just take a .jar from a Java library and use it in an Android application. Android uses the Dalvik JVM (http://en.wikipedia.org/wiki/Dalvik_(software)) which is not 100% compatible with the full API from the Java SE API, and instead only supports a subset of the API. For this reason, many of the Java libraries you might be use to, like FOP, are not Android compatible as-is and require specialization before such libraries will function properly on an Android device. Good luck.

来源：https://stackoverflow.com/questions/5083162/fop-for-android