android - 如何使用谷歌云打印机在android中打印文本文件

Question

我在我的项目中实现了谷歌云打印，但是当我在谷歌云中附加文本文件时，它显示要打印的 1 页但不显示其内容。

那么当文件附加到谷歌云时如何显示文本文件的内容以及如何从用户手机获取现有的谷歌帐户以及如何设置谷歌浏览器以从我的代码打印，以便用户轻松从我的应用程序打印文档.所以请提供代码或一些好的教程以我的要求方式处理谷歌云。

Intent printIntent = new Intent(ExportActivity.this, PrintDialogActivity.class);
printIntent.setDataAndType(Uri.fromFile(file), "text/*");
printIntent.putExtra("title", "Dictionary");


public class PrintDialogActivity extends Activity {
    private static final String PRINT_DIALOG_URL = "https://www.google.com/cloudprint/dialog.html";
    private static final String JS_INTERFACE = "AndroidPrintDialog";
    private static final String CONTENT_TRANSFER_ENCODING = "base64";

    private static final String ZXING_URL = "http://zxing.appspot.com";
    private static final int ZXING_SCAN_REQUEST = 65743;

    /**
     * Post message that is sent by Print Dialog web page when the printing dialog needs to be closed.
     */
    private static final String CLOSE_POST_MESSAGE_NAME = "cp-dialog-on-close";

    /**
     * Web view element to show the printing dialog in.
     */
    private WebView dialogWebView;

    /**
     * Intent that started the action.
     */
    Intent cloudPrintIntent;

    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.print_dialog);
        dialogWebView = (WebView) findViewById(R.id.webview);
        cloudPrintIntent = this.getIntent();
        WebSettings settings = dialogWebView.getSettings();
        settings.setJavaScriptEnabled(true);
        dialogWebView.setWebViewClient(new PrintDialogWebClient());
        dialogWebView.addJavascriptInterface(new PrintDialogJavaScriptInterface(), JS_INTERFACE);
        dialogWebView.loadUrl(PRINT_DIALOG_URL);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent intent) {
        if (requestCode == ZXING_SCAN_REQUEST && resultCode == RESULT_OK) {
            dialogWebView.loadUrl(intent.getStringExtra("SCAN_RESULT"));
        }
    }

    final class PrintDialogJavaScriptInterface {
        public String getType() {
            return cloudPrintIntent.getType();
        }

        public String getTitle() {
            return cloudPrintIntent.getExtras().getString("title");
        }

        public String getContent() {
            try {
                ContentResolver contentResolver = getContentResolver();
                InputStream is = contentResolver.openInputStream(cloudPrintIntent.getData());
                ByteArrayOutputStream baos = new ByteArrayOutputStream();

                byte[] buffer = new byte[4096];
                int n = is.read(buffer);
                while (n >= 0) {
                    baos.write(buffer, 0, n);
                    n = is.read(buffer);
                }
                is.close();
                baos.flush();

                return Base64.encodeToString(baos.toByteArray(), Base64.DEFAULT);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return "";
        }

        public String getEncoding() {
            return CONTENT_TRANSFER_ENCODING;
        }

        public void onPostMessage(String message) {
            if (message.startsWith(CLOSE_POST_MESSAGE_NAME)) {
                finish();
            }
        }
    }

    private final class PrintDialogWebClient extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (url.startsWith(ZXING_URL)) {
                Intent intentScan = new Intent("com.google.zxing.client.android.SCAN");
                intentScan.putExtra("SCAN_MODE", "QR_CODE_MODE");
                try {
                    startActivityForResult(intentScan, ZXING_SCAN_REQUEST);
                } catch (ActivityNotFoundException error) {
                    view.loadUrl(url);
                }
            } else {
                view.loadUrl(url);
            }
            return false;
        }

        @Override
        public void onPageFinished(WebView view, String url) {
            if (PRINT_DIALOG_URL.equals(url)) {
                // Submit print document.
                view.loadUrl("javascript:printDialog.setPrintDocument(printDialog.createPrintDocument(" + "window." + JS_INTERFACE + ".getType(),window." + JS_INTERFACE + ".getTitle()," + "window." + JS_INTERFACE + ".getContent(),window." + JS_INTERFACE + ".getEncoding()))");

                // Add post messages listener.
                view.loadUrl("javascript:window.addEventListener('message'," + "function(evt){window." + JS_INTERFACE + ".onPostMessage(evt.data)}, false)");
            }
        }
    }
}