如何使用PdfRenderer在Android上呈现PDF

我在这两种情况下都失败了：

private void render() {
    try {
        imageView = (ImageView) findViewById(R.id.page);

        int REQ_WIDTH = 1;
        int REQ_HEIGHT = 1;
        REQ_WIDTH = imageView.getWidth();
        REQ_HEIGHT = imageView.getHeight();

        Bitmap bitmap = Bitmap.createBitmap(REQ_WIDTH, REQ_HEIGHT, Bitmap.Config.ARGB_4444);

        File file = new File(Environment.getExternalStorageDirectory() + "/Download/test.pdf");

        PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));

        if (currentPage < 0) {
            currentPage = 0;
        } else if (currentPage > renderer.getPageCount()) {
            currentPage = renderer.getPageCount() - 1;
        }

        Matrix matrix = imageView.getImageMatrix();
        Rect rect = new Rect(0, 0, REQ_WIDTH, REQ_HEIGHT);

        renderer.openPage(currentPage).render(bitmap, rect, matrix, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);

        imageView.setImageMatrix(matrix);
        imageView.setImageBitmap(bitmap);
        imageView.invalidate();
        renderer.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
}

1。试图从手机存储器中打开它
2.试图从资产中打开它

private void render() {
    try {
        imageView = (ImageView) findViewById(R.id.page);

        int REQ_WIDTH = 1;
        int REQ_HEIGHT = 1;
        REQ_WIDTH = imageView.getWidth();
        REQ_HEIGHT = imageView.getHeight();

        Bitmap bitmap = Bitmap.createBitmap(REQ_WIDTH, REQ_HEIGHT, Bitmap.Config.ARGB_4444);

        File file = new File(Environment.getExternalStorageDirectory() + "/Download/test.pdf");

        PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));

        if (currentPage < 0) {
            currentPage = 0;
        } else if (currentPage > renderer.getPageCount()) {
            currentPage = renderer.getPageCount() - 1;
        }

        Matrix matrix = imageView.getImageMatrix();
        Rect rect = new Rect(0, 0, REQ_WIDTH, REQ_HEIGHT);

        renderer.openPage(currentPage).render(bitmap, rect, matrix, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);

        imageView.setImageMatrix(matrix);
        imageView.setImageBitmap(bitmap);
        imageView.invalidate();
        renderer.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
}

我有render（）方法，在第一种情况下如下所示：

private void render() {
    try {
        imageView = (ImageView) findViewById(R.id.page);

        int REQ_WIDTH = 1;
        int REQ_HEIGHT = 1;
        REQ_WIDTH = imageView.getWidth();
        REQ_HEIGHT = imageView.getHeight();

        Bitmap bitmap = Bitmap.createBitmap(REQ_WIDTH, REQ_HEIGHT, Bitmap.Config.ARGB_4444);

        File file = new File(Environment.getExternalStorageDirectory() + "/Download/test.pdf");

        PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));

        if (currentPage < 0) {
            currentPage = 0;
        } else if (currentPage > renderer.getPageCount()) {
            currentPage = renderer.getPageCount() - 1;
        }

        Matrix matrix = imageView.getImageMatrix();
        Rect rect = new Rect(0, 0, REQ_WIDTH, REQ_HEIGHT);

        renderer.openPage(currentPage).render(bitmap, rect, matrix, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);

        imageView.setImageMatrix(matrix);
        imageView.setImageBitmap(bitmap);
        imageView.invalidate();
        renderer.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
}

让我们看看第二个案例（从资产中阅读）：

private void render() {
    try {
        imageView = (ImageView) findViewById(R.id.page);

        int REQ_WIDTH = 1;
        int REQ_HEIGHT = 1;
        REQ_WIDTH = imageView.getWidth();
        REQ_HEIGHT = imageView.getHeight();

        Bitmap bitmap = Bitmap.createBitmap(REQ_WIDTH, REQ_HEIGHT, Bitmap.Config.ARGB_4444);

        File file = new File(Environment.getExternalStorageDirectory() + "/Download/test.pdf");

        PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));

        if (currentPage < 0) {
            currentPage = 0;
        } else if (currentPage > renderer.getPageCount()) {
            currentPage = renderer.getPageCount() - 1;
        }

        Matrix matrix = imageView.getImageMatrix();
        Rect rect = new Rect(0, 0, REQ_WIDTH, REQ_HEIGHT);

        renderer.openPage(currentPage).render(bitmap, rect, matrix, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);

        imageView.setImageMatrix(matrix);
        imageView.setImageBitmap(bitmap);
        imageView.invalidate();
        renderer.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
}

在本例中，它说的是相同的，但如果我没记错的话，smth说，

无法创建文档

，但现在它消失了，异常看起来是一样的。不管怎样，为什么我要开始谈论第二个案子？说META-INF应该在apk的末尾。我的是最后一个，它仍然不工作

private void render() {
    try {
        imageView = (ImageView) findViewById(R.id.page);

        int REQ_WIDTH = 1;
        int REQ_HEIGHT = 1;
        REQ_WIDTH = imageView.getWidth();
        REQ_HEIGHT = imageView.getHeight();

        Bitmap bitmap = Bitmap.createBitmap(REQ_WIDTH, REQ_HEIGHT, Bitmap.Config.ARGB_4444);

        File file = new File(Environment.getExternalStorageDirectory() + "/Download/test.pdf");

        PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));

        if (currentPage < 0) {
            currentPage = 0;
        } else if (currentPage > renderer.getPageCount()) {
            currentPage = renderer.getPageCount() - 1;
        }

        Matrix matrix = imageView.getImageMatrix();
        Rect rect = new Rect(0, 0, REQ_WIDTH, REQ_HEIGHT);

        renderer.openPage(currentPage).render(bitmap, rect, matrix, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);

        imageView.setImageMatrix(matrix);
        imageView.setImageBitmap(bitmap);
        imageView.invalidate();
        renderer.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
}

坦白说，我甚至试过Androidstudio本身的一个例子。你知道吗？它起作用了！但是只有在他们的

sample.pdf

中，当我试图用我的替换它时，它就崩溃了。你知道我可以尝试在Android上制作什么样的pdf渲染吗

private void render() {
    try {
        imageView = (ImageView) findViewById(R.id.page);

        int REQ_WIDTH = 1;
        int REQ_HEIGHT = 1;
        REQ_WIDTH = imageView.getWidth();
        REQ_HEIGHT = imageView.getHeight();

        Bitmap bitmap = Bitmap.createBitmap(REQ_WIDTH, REQ_HEIGHT, Bitmap.Config.ARGB_4444);

        File file = new File(Environment.getExternalStorageDirectory() + "/Download/test.pdf");

        PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));

        if (currentPage < 0) {
            currentPage = 0;
        } else if (currentPage > renderer.getPageCount()) {
            currentPage = renderer.getPageCount() - 1;
        }

        Matrix matrix = imageView.getImageMatrix();
        Rect rect = new Rect(0, 0, REQ_WIDTH, REQ_HEIGHT);

        renderer.openPage(currentPage).render(bitmap, rect, matrix, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);

        imageView.setImageMatrix(matrix);
        imageView.setImageBitmap(bitmap);
        imageView.invalidate();
        renderer.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
}

---

所有内容都在Nexus 5、Android 6.0棉花糖上进行了测试。

除了清单中的权限外，您可能还需要明确请求权限。比如：

private void render() {
    try {
        imageView = (ImageView) findViewById(R.id.page);

        int REQ_WIDTH = 1;
        int REQ_HEIGHT = 1;
        REQ_WIDTH = imageView.getWidth();
        REQ_HEIGHT = imageView.getHeight();

        Bitmap bitmap = Bitmap.createBitmap(REQ_WIDTH, REQ_HEIGHT, Bitmap.Config.ARGB_4444);

        File file = new File(Environment.getExternalStorageDirectory() + "/Download/test.pdf");

        PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));

        if (currentPage < 0) {
            currentPage = 0;
        } else if (currentPage > renderer.getPageCount()) {
            currentPage = renderer.getPageCount() - 1;
        }

        Matrix matrix = imageView.getImageMatrix();
        Rect rect = new Rect(0, 0, REQ_WIDTH, REQ_HEIGHT);

        renderer.openPage(currentPage).render(bitmap, rect, matrix, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);

        imageView.setImageMatrix(matrix);
        imageView.setImageBitmap(bitmap);
        imageView.invalidate();
        renderer.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
}

int permission = ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE);

if (permission != PackageManager.PERMISSION_GRANTED)
{
    // We don't have permission so prompt the user
    ActivityCompat.requestPermissions(getActivity(), PERMISSIONS_STORAGE, REQUEST_EXTERNAL_STORAGE);
}