Android Annotation processor access resources (assets)

问题

I want to access a resource from my andoid studio project in my annotation processor.

I first tried to use the getResource method from filer:

FileObject fo = processingEnv.getFiler().getResource(StandardLocation.SOURCE_PATH, "", "src/main/res/layout/activity_main.xml");

, but it always throwed a exception that just returned "src/main/res/layout/activity_main.xml" as a message.

Next think i have tried was

this.getClass().getResource("src/main/res/layout/activity_main.xml")

, but this always returned null.

The last think i have tried to use was this:

JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
            StandardJavaFileManager fm = compiler.getStandardFileManager(null, null, null);
            Iterable<? extends File> locations = fm.getLocation(StandardLocation.SOURCE_PATH);
            for (File file : locations) {
                System.out.print(file.getAbsolutePath());
            }

, but it throwes a null pointer exception

回答1:

I used the following to get the layout folder from my annotation processor:

private File findLayouts() throws Exception {
        Filer filer = processingEnv.getFiler();

        JavaFileObject dummySourceFile = filer.createSourceFile("dummy" + System.currentTimeMillis());
        String dummySourceFilePath = dummySourceFile.toUri().toString();

        if (dummySourceFilePath.startsWith("file:")) {
            if (!dummySourceFilePath.startsWith("file://")) {
                dummySourceFilePath = "file://" + dummySourceFilePath.substring("file:".length());
            }
        } else {
            dummySourceFilePath = "file://" + dummySourceFilePath;
        }

        URI cleanURI = new URI(dummySourceFilePath);

        File dummyFile = new File(cleanURI);

        File projectRoot = dummyFile.getParentFile().getParentFile().getParentFile().getParentFile().getParentFile().getParentFile();

        return new File(projectRoot.getAbsolutePath() + "/src/main/res/layout");
    }

回答2:

Processor instance runs at the root level of the project, so you can do it in an easy way like so:

String fileSeparator = System.getProperty("file.separator");
    String absoluteFilePth = "app" + fileSeparator + "src" + fileSeparator + "main" + fileSeparator + "res" + fileSeparator + "layout";
    File file = new File(absoluteFilePth);

Regards,

来源：https://stackoverflow.com/questions/37225786/android-annotation-processor-access-resources-assets